Debt Disclosure [Abstract] Schedule of debt obligations Schedule of Debt [Table Text Block] Schedule of future scheduled maturities of outstanding long-term debt obligations, net Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of carrying value of encumbered assets by asset type Schedule of Encumbered Assets [Table Text Block] Tabular disclosure of assets which were encumbered with mortgages or pledged as collateral for borrowings at the end of the reporting period(s). Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Real Estate [Abstract] Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Real Estate Property Ownership [Axis] Real Estate Property Ownership [Axis] Real Estate Properties [Domain] Real Estate Properties [Domain] Operating Properties Operating Properties [Member] Operating Properties [Member] Net Lease Net Lease Asset [Member] Represents details pertaining to net lease assets. Total Operating Properties and Net Lease [Member] Operating Properties and Net Lease [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Proceeds Proceeds from Sale of Real Estate Held-for-investment Income from sales of real estate Gain (Loss) on Sale of Properties Receivables [Abstract] Amortized Cost Basis Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract] Within one year Held-to-maturity Securities, Debt Maturities, within One Year, Net Carrying Amount After one year through 5 years Held-to-maturity Securities, Debt Maturities, after One Through Five Years, Net Carrying Amount After 5 years through 10 years Held-to-maturity Securities, Debt Maturities, after Five Through Ten Years, Net Carrying Amount After 10 years Held-to-maturity Securities, Debt Maturities, after Ten Years, Net Carrying Amount Amortized Cost Basis Held-to-maturity Securities, Amortized Cost before Other than Temporary Impairment Estimated Fair Value Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract] Within one year Held-to-maturity Securities, Debt Maturities, Next Twelve Months, Fair Value After one year through 5 years Held-to-maturity Securities, Debt Maturities, Year Two Through Five, Fair Value After 5 years through 10 years Held-to-maturity Securities, Debt Maturities, Year Six Through Ten, Fair Value After 10 years Held-to-maturity Securities, Debt Maturities, after Ten Years, Fair Value Total Held-to-maturity Securities, Fair Value Amortized Cost Basis Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract] Within one year Available-for-sale Securities, Debt Maturities, Next Twelve Months, Amortized Cost Basis After one year through 5 years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Amortized Cost Basis After 5 years through 10 years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Amortized Cost Basis After 10 years Available-for-sale Securities, Debt Maturities, after Ten Years, Amortized Cost Basis Amortized Cost Basis Available-for-sale Debt Securities, Amortized Cost Basis Estimated Fair Value Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract] Within one year Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value After one year through 5 years Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value After 5 years through 10 years Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Fair Value After 10 years Available-for-sale Securities, Debt Maturities, after Ten Years, Fair Value Total Available-for-sale Securities, Debt Securities, Fair Value Available-for-sale Securities, Debt Securities, Fair Value Fair Value Disclosures [Abstract] Fair Values Fair Value Disclosures [Text Block] Schedule of Debt Securities [Table] Schedule of Available-for-sale Securities [Table] Debt Security [Axis] Debt Security [Axis] Major Types of Debt Securities [Domain] Major Types of Debt Securities [Domain] Municipal debt securities Municipal Bonds [Member] Debt securities Corporate Debt Securities [Member] Schedule of Debt Securities [Line Items] Schedule of Available-for-sale Securities [Line Items] Available-for-Sale Securities Available-for-sale Securities, Fair Value to Amortized Cost Basis [Abstract] Face Value Available-for-sale Securities, Debt Security, Face Amount Available-for-sale Securities, Debt Security, Face Amount Net Unrealized Gain (Loss) Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax Estimated Fair Value Net Carrying Value Available-for-sale Securities, Debt Securities Held-to-Maturity Securities Held-to-maturity Securities, Debt Maturities [Abstract] Face Value Held-to-maturity Securities, Debt Security, Face Amount Held-to-maturity Securities, Debt Security, Face Amount Net Unrealized Gain (Loss) Held-to-Maturity Securities, Accumulated Unrealized Holding Gain (Loss) Held-to-Maturity Securities, Accumulated Unrealized Holding Gain (Loss) Estimated Fair Value Net Carrying Value Held-to-maturity Securities Investments, Debt and Equity Securities [Abstract] Investments, Debt and Equity Securities [Abstract] Face Value Debt Securities, Face Amount Debt Securities, Face Amount Amortized Cost Basis Debt Securities, Amortized Cost Basis Debt Securities, Amortized Cost Basis Net Unrealized Gain (Loss) Debt Securities, Unrealized Holding Gains Debt Securities, Unrealized Holding Gains Estimated Fair Value Debt Securities, Fair Value Debt Securities, Fair Value Net Carrying Value Debt Securities, Net Carrying Amount Debt Securities, Net Carrying Amount Equity [Abstract] Schedule of Stock by Class [Table] Schedule of Stock by Class [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Series D Series D Preferred Stock [Member] Series G Series G Preferred Stock [Member] Series I Series I Preferred Stock [Member] Outstanding nonredeemable series I preferred stock or outstanding series I preferred stock. Classified within stockholders' equity if nonredeemable or redeemable solely at the option of the issuer. Classified within temporary equity if redemption is outside the control of the issuer. Series J Series J Preferred Stock [Member] Series J Preferred Stock [Member] Series E Series E Preferred Stock [Member] Series F Series F Preferred Stock [Member] Series G And Series I Preferred Stock [Member] Series G And Series I Preferred Stock [Member] Series G And Series I Preferred Stock [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Maximum Maximum [Member] Minimum Minimum [Member] Class of Stock [Line Items] Class of Stock [Line Items] Operating loss carryforwards Operating Loss Carryforwards Shares Issued and Outstanding (in shares) Preferred Stock Shares Issued and Outstanding Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury) and held by stockholders. May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt and preferred shares that have been repurchased. Par Value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Liquidation Preference (in dollars per share) Preferred Stock, Liquidation Preference Per Share Rate per Annum Preferred Stock, Dividend Rate, Percentage Equivalent to Fixed Annual Rate (in dollars per share) Preferred Stock, Dividend Rate, Per-Dollar-Amount Carrying value of preferred stock Preferred Stock, Value, Outstanding Number of days in year used in the computation of preferred stock dividends for any partial dividend period Preferred Stock, Dividends Computation of Dividends Payable for Any Partial Dividend Period, Number of Days in Year Represents the number of days in year used in the computation of preferred stock dividends for any partial dividend period. Number of months used in the computation of preferred stock dividends for any partial dividend period Preferred Stock, Dividends Computation of Dividends Payable for Any Partial Dividend Period, Number of Months Represents the number of months used in the computation of preferred stock dividends for any partial dividend period. Number of days in month, dividends computation of dividends payable for any partial dividend period Preferred Stock, Dividends Computation of Dividends Payable for Any Partial Dividend Period, Number of Days in Month Represents the number of days in month used in the computation of preferred stock dividends for any partial dividend period. Number of days prior to dividend payment date that Board of Directors may elect to designate as the payment date Preferred Stock Dividends, Number of Days Prior to Dividend Payment Date That Board of Directors May Elect to Designate as Payment Date Represents the number of days prior to dividend payment date that Board of Directors may elect to designate as the payment date. Dividends declared and paid Dividends declared and paid Aggregate dividends declared and paid during the period for each share of common stock outstanding. Capital gains distribution (as a percent) Capital Gains Distribution, Percentage Capital Gains Distribution, Percentage Unrecaptured Section 1250 gain (s a percent) Unrecaptured Section 1250 Gain, Percentage of Dividend Unrecaptured Section 1250 Gain, Percentage of Dividend Long term capital gain (as a percent) Long Term Capital Gain, Percentage of Dividend Long Term Capital Gain, Percentage of Dividend Amount of preferred dividends in arrears Preferred Stock, Amount of Preferred Dividends in Arrears Redemption price as a percentage of liquidation preference Preferred Stock, Redemption Price as a Percentage of Liquidation Preference Preferred Stock, Redemption Price as a Percentage of Liquidation Preference Shares issued upon conversion Convertible Preferred Stock, Shares Issued upon Conversion Conversion price per share (in dollars per share) Convertible Preferred Stock, Conversion Price Per Share Convertible Preferred Stock, Conversion Price Per Share Other Commitments [Table] Other Commitments [Table] Unfunded Financial Commitments [Axis] Unfunded Financial Commitments [Axis] Information by arrangements in which the entity has committed to off-balance sheet financial commitments. Unfunded Financial Commitments [Domain] Unfunded Financial Commitments [Domain] This item is intended to be populated, by the entity, with Members identifying each off-balance sheet financial commitment. Loans and Other Lending Investments Loans Receivable [Member] Real Estate Real Estate [Member] Other Investments Other Investments [Member] Loan participations, not the obligation of the Company Loan Participations Payable [Member] Loan Participations Payable [Member] Other Commitments [Line Items] Other Commitments [Line Items] Performance-Based Commitments Performance-Based Commitments Represents the off-balance sheet unfunded maximum amount of funds for construction and development loans and build-outs of space in net lease assets over a period of time if and when the borrowers and tenants meet established milestones and other performance criteria. Strategic Investments Other Commitments Represents the off-balance sheet maximum other commitments of the entity. Total Unfunded Commitments Represents certain off-balance sheet unfunded commitments of the entity. Land and development [Abstract] Land and development [Abstract] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Land & Development Land [Member] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Land and land development, at cost Land and land development Land and land development Less: accumulated depreciation Real Estate Investment Property, Accumulated Depreciation and Amortization Real Estate Investment Property, Accumulated Depreciation and Amortization Total land and development, net Inventory, Real Estate, Land and Land Development Costs Capital expenditures on land and development assets Payment for Capital Expenditures on Land and Development Assets Payment for Capital Expenditures on Land and Development Assets Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Beginning balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Repayments Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements Unrealized gains recorded in other comprehensive income Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss) Ending balance Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event Subsequent Event [Member] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] 2015 $325 million Revolving Credit Facility Secured Revolving Credit Facility Due September 2020 [Member] Secured Revolving Credit Facility Due September 2020 [Member] 2016 Senior Credit Facility 2016 Senior Secured Credit Facility [Member] 2016 Senior Secured Credit Facility [Member] Mortgages collateralized by net lease assets Secured Term Loans Collateralized by Loans Net Lease Assets Due Through 2026 [Member] Secured Term Loans Collateralized by net lease assets due through 2026 debt instrument of the entity. Total secured credit facilities and mortgages Secured Credit Facilities [Member] Represents the secured credit facility of the entity. 5.00% senior notes Unsecured Notes Five Percent Senior Notes Due July 2019 [Member] Unsecured Notes Five Percent Senior Notes Due July 2019 [Member] 4.625% senior notes Unsecured 4.625% Senior Notes Due September 2020 [Member] Unsecured 4.625% Senior Notes Due September 2020 [Member] 6.50% senior notes Unsecured Notes Six Point Five Percent Senior Notes Due July 2021 [Member] Unsecured Notes Six Point Five Percent Senior Notes Due July 2021 [Member] 6.00% senior notes Unsecured Six Percent Senior Notes Due April 2022 [Member] Unsecured Six Percent Senior Notes Due April 2022 [Member] 5.25% senior notes Unsecured 5.25% Senior Notes Due September 2022 [Member] Unsecured 5.25% Senior Notes Due September 2022 [Member] 3.125% senior convertible notes Unsecured 3.125% Senior Convertible Notes Due September 2022 [Member] Unsecured 3.125% Senior Convertible Notes Due September 2022 [Member] Unsecured Notes Unsecured Senior Notes [Member] Represents the unsecured senior notes of the entity. Trust preferred securities Other Debt Securities, Due October 2035 [Member] Represents other debt obligations due in October, 2035. Variable Rate [Axis] Variable Rate [Axis] Variable Rate [Domain] Variable Rate [Domain] London Interbank Offered Rate (LIBOR) London Interbank Offered Rate (LIBOR) [Member] Federal Funds Effective Swap Rate Federal Funds Effective Swap Rate [Member] Debt Instrument, Interest Rate Category [Axis] Debt Instrument, Interest Rate Category [Axis] Debt Instrument, Interest Rate Category [Axis] Debt Instrument, Interest Rate Category [Domain] Debt Instrument, Interest Rate Category [Domain] [Domain] for Debt Instrument, Interest Rate Category [Axis] Interest Rate Category One Interest Rate Category One [Member] Interest Rate Category One [Member] Interest Rate Category Two Interest Rate Category Two [Member] Interest Rate Category Two [Member] Debt Instrument [Line Items] Debt Instrument [Line Items] Debt instrument, face amount Debt Instrument, Face Amount Total debt obligations Long-term Debt, Gross Debt discounts and deferred financing costs, net Debt Instrument, Unamortized Discount (Premium) and Deferred Financing Costs, Net Debt Instrument, Unamortized Discount (Premium) and Deferred Financing Costs, Net Total debt obligations, net Long-term Debt Stated interest rates (as a percent) Debt Instrument, Interest Rate, Stated Percentage Basis point spread on variable interest rate (as a percent) Debt Instrument, Basis Spread on Variable Rate Debt instrument, margin (as a percent) Debt Instrument, Margin Debt Instrument, Margin Converted term loan, term Converted Term Loan, Term Converted Term Loan, Term Weighted average interest rate (as a percent) Debt, Weighted Average Interest Rate Convertible debt, conversion ratio (in shares per par value) Debt Instrument, Convertible, Conversion Ratio Convertible debt, conversion price (in dollars per share) Debt Instrument, Convertible, Conversion Price Liability component of convertible debt Convertible Debt Carrying value of equity component of convertible debt Debt Instrument, Convertible, Carrying Amount of Equity Component Debt Instrument, Unamortized Discount Debt Instrument, Unamortized Discount Interest Expense, Debt Interest Expense, Debt Amortization of Debt Discount (Premium) Amortization of Debt Discount (Premium) Effective interest rate Debt Instrument, Interest Rate, Effective Percentage Interest costs capitalized Interest Costs Capitalized Statement of Comprehensive Income [Abstract] Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Impact from adoption of new accounting standards Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Adoption of New Accounting Standard Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Adoption of New Accounting Standard Reclassification of (gains)/losses on cash flow hedges into earnings upon realization Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax Unrealized losses on available-for-sale securities Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Unrealized gains on cash flow hedges Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Unrealized losses on cumulative translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Other comprehensive income Other Comprehensive Income (Loss), Net of Tax Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive (income) loss attributable to noncontrolling interests Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income (loss) attributable to iStar Inc. Comprehensive Income (Loss), Net of Tax, Attributable to Parent Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Unsecured Notes Four Percent Senior Notes Due November 2017 Unsecured Notes Four Percent Senior Notes Due November 2017 [Member] Unsecured Notes Four Percent Senior Notes Due November 2017 [Member] Unsecured Notes Seven Point One Two Five Percent Senior Notes Due February 2018 Unsecured Notes Seven Point One Two Five Percent Senior Notes Due February 2018 [Member] Unsecured Notes Seven Point One Two Five Percent Senior Notes Due February 2018 [Member] Unsecured Notes 4 point 875 Percent Senior Notes Due July 2018 Unsecured Notes 4 point 875 Percent Senior Notes Due July 2018 [Member] Unsecured Notes 4 point 875 Percent Senior Notes Due July 2018 [Member] 5.85% senior notes Unsecured Notes 5 point 85 Percent Senior Notes Due March 2017 [Member] Unsecured Notes 5.85% due March 2017 senior notes debt instrument of the entity. 9.00% senior notes Unsecured Notes Nine Percent Senior Notes Due June 2017 [Member] Unsecured Notes Nine Percent Senior Notes Due June 2017 [Member] Extinguishment of debt, amount Extinguishment of Debt, Amount Deferred financing costs Debt Issuance Costs, Gross Repayments of debt Repayments of Debt Accumulated other comprehensive income (loss) reflected in the Company's shareholders' equity Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Unrealized gains on available-for-sale securities Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Unrealized gains on cash flow hedges Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Unrealized losses on cumulative translation adjustment Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Segment Reporting [Abstract] Segment Reporting Segment Reporting Disclosure [Text Block] Schedule of real estate assets Schedule of Real Estate Assets [Table Text Block] Schedule of Real Estate Assets [Table Text Block] Income (loss) from discontinued operations Disposal Groups, Including Discontinued Operations [Table Text Block] Schedule of other dispositions Schedule of Proceeds from Other Dispositions [Table Text Block] Schedule of Proceeds from Other Dispositions [Table Text Block] Dividends [Abstract] Dividends [Abstract] Minimum percentage of taxable income (excluding net capital gains) to be distributed in order to qualify as REIT Minimum Percentage of Taxable Income Excluding Capital Gains to be Distributed to Qualify as REIT Represents the minimum percentage of taxable income (excluding capital gains) to be distributed in order to qualify as REIT. Percentage of taxable income (including net capital gains) to be distributed in order to qualify as REIT Percentage of Taxable Income Including Capital Gains to be Distributed to Qualify as REIT Represents the percentage of taxable income (including capital gains) to be distributed in order to qualify as REIT. Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis of Presentation and Principles of Consolidation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Asset Class [Axis] Asset Class [Axis] Asset Class [Domain] Asset Class [Domain] Collateral Assets Encumbered Assets [Member] Encumbered Assets [Member] Non-Collateral Assets Unencumbered Assets [Member] Unencumbered Assets [Member] Evaluation Type [Axis] Evaluation Type [Axis] Evaluation Type [Axis] Evaluation Type [Domain] Evaluation Type [Domain] [Domain] for Evaluation Type [Axis] Collectively Evaluated for Impairment Collectively Evaluated for Impairment [Member] Collectively Evaluated for Impairment [Member] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Total loan participations payable, net Real estate, net Real Estate Investment Property, Held for Use, Net Real Estate Investment Property, Held for Use, Net Real estate available and held for sale Real Estate Available and Held for Sale Carrying amount as of the balance sheet date of investments in land and buildings held for sale, including real estate considered to be inventory of the entity. Land and development, net Loans receivable and other lending investments, net Loans and Other Lending Investments Amount representing an agreement for an unconditional promise by the maker to pay the Entity (holder) a definite sum of money at a future date, net of any write-downs taken for collection uncertainty on the part of the holder. Such amount may include accrued interest receivable in accordance with the terms of the note. The note also may contain provisions and related items including a discount or premium, payable on demand, secured, or unsecured, interest bearing or noninterest bearing, among myriad other features and characteristics. In addition, amount also includes total debt and equity financial instruments including: securities held-to-maturity and securities available-for-sale. Other investments Other Investments Cash and other assets Cash and Other Assets Sum of all assets excluding the Company's Total Portfolio Assets. Total assets Assets General reserves for loan losses Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment Loans receivable, net Loans Receivable, Net Number of reportable segments Number of Reportable Segments Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Consolidation Items [Axis] Consolidation Items [Axis] Consolidation Items [Domain] Consolidation Items [Domain] Operating Segments Operating Segments [Member] Corporate/Other Corporate, Non-Segment [Member] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Real Estate Finance Real Estate Lending [Member] Represents the Real Estate Lending segment that includes all of the Company's activities related to senior and mezzanine real estate debt and corporate capital investments. Net Lease Net Leasing [Member] Represents the Net Leasing segment that includes all of the company's activities related to the ownership and leasing of corporate facilities. Operating Properties Operating Property [Member] Operating Property [Member] Land and Development Land and Development Segment [Member] Land and Development Segment [Member] Segment Reporting Segment Reporting Information [Line Items] Operating lease income Operating Leases, Income Statement, Lease Revenue Interest income Interest and Fee Income, Loans, Commercial Other income Other Income Land development revenue Land Sales Earnings (losses) from equity method investments Income (Loss) from Equity Method Investments Income from discontinued operations Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax Total revenue and other earnings Revenue and Other Earnings The sum of the Company's total revenue and other earnings related to the Company's business segments. Real estate expense Cost of Real Estate Held-for-Sale and Other Real Estate Owned This element represents the aggregate of the holding and operating costs related to real estate held for investment and the net costs related to other real estate owned. Land development cost of sales Costs of Land Sales Costs of Land Sales Other expense Other Expenses Allocated interest expense Interest Expense Including Discontinued Operations The cost of borrowed funds accounted for as interest that was charged against earnings during the period including amounts presented in discontinued operations. Allocated general and administrative General and Administrative Expense Excluding Stock-based Compensation Expense The aggregate total of expenses of managing and administering the affairs of the entity, including affiliates of the reporting entity, which are not directly or indirectly associated with the manufacture, sale or creation of a product or product line, excluding stock-based compensation expense. Segment profit (loss) Segment Profit (Loss) Amount of profit or loss during the period recognized by the reportable segment. Other significant items: Segment Reporting, Other Significant Reconciling Item, Consolidated [Abstract] Recovery of loan losses Allowance for Loan and Lease Loss, Recovery of Bad Debts, Net of (Provision for Loan and Lease Losses) Allowance for Loan and Lease Loss, Recovery of Bad Debts, Net of (Provision for Loan and Lease Losses) Impairment of assets Asset Impairment Charges Including Discontinued Operations The charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value including amounts presented in discontinued operations. Depreciation and amortization Depreciation and Amortization Including Discontinued Operations The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production including amounts presented in discontinued operations. Capitalized expenditures Real Estate and Accumulated Depreciation Costs, Capitalized Subsequent to Acquisition Carrying amount as of the balance sheet date of costs that were capitalized after acquisition, including property improvements and carrying costs (for example, real estate taxes and insurance), but excluding the initial purchase price. Real estate available and held for sale Total real estate Real Estate Investment Property, Net Land and development, net Loans receivable and other lending investments, net Other investments Total portfolio assets Portfolio Assets The aggregate of Total real estate, loans receivable, net and Other investments. Cash and other assets Stock-based compensation expense Allocated Share-based Compensation Expense Unsecured Debt Unsecured Debt [Member] Secured Debt Secured Debt [Member] Maturities of Long-term Debt [Abstract] Maturities of Long-term Debt [Abstract] 2018 (remaining nine months) Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year 2018 Long-term Debt, Maturities, Repayments of Principal in Year Two 2019 Long-term Debt, Maturities, Repayments of Principal in Year Three 2020 Long-term Debt, Maturities, Repayments of Principal in Year Four 2021 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Total principal maturities Unamortized discounts and deferred financing costs, net Schedule of Financing Receivables Past Due [Table] Schedule of Financing Receivables Past Due [Table] Receivable Type [Axis] Receivable Type [Axis] Receivable [Domain] Receivable [Domain] Senior mortgages First Mortgage [Member] Corporate/Partnership loans Corporate/Partnership Loan [Member] Corporate/Partnership Loan [Member] Subordinate mortgages Second Mortgage [Member] Recorded investment in loans, aged by payment status and presented by class Financing Receivable, Recorded Investment, Past Due [Line Items] Current Financing Receivable, Recorded Investment, Current Less Than and Equal to 90 Days Financing Receivable Recorded Investment Equal to Less than 90 Days Past Due Financing receivables that are equal to or less than 90 days past due. Greater Than 90 Days Financing Receivable Recorded Investment Greater than 90 Days Past Due Financing receivables that are greater than 90 days past due. Total Past Due Financing Receivable, Recorded Investment, Past Due Loans Financing Receivable, Gross Financing receivable, number of loans greater than 90 days past due Financing Receivable, Number of Loans Greater than 90 Days Past Due Financing Receivable, Number of Loans Greater than 90 Days Past Due Financing receivables, past due time period Financing Receivables, Past Due Time Period Financing Receivables, Past Due Time Period Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] Schedule of unfunded commitments Unfunded Financial Commitments [Table Text Block] Tabular disclosure of off-balance sheet unfunded financial commitments which includes performance-based commitments, discretionary funding arrangements and strategic investment commitments. Gain Contingencies, Nature [Axis] Gain Contingencies, Nature [Axis] Gain Contingency, Nature [Domain] Gain Contingency, Nature [Domain] Positive Outcome of Litigation [Member] Positive Outcome of Litigation [Member] Litigation Case [Axis] Litigation Case [Axis] Litigation Case [Domain] Litigation Case [Domain] Lennar U.S. Home Corporation (Lennar) [Member] Lennar [Member] Percentage of capital committed to strategic investments that may be drawn down Percentage of Capital Committed that May be Drawn Down Represents the percentage of capital committed to strategic investments by the entity that may be drawn down. Legal fee recovery, applied amount Gain Contingency, Unrecorded Amount Loans Receivable and Other Lending Investments, net Loans and Other Lending Investments Net [Text Block] This element represents a summarization of loans and other lending investments held by the company. Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Measurement Basis [Axis] Measurement Basis [Axis] Fair Value Measurement [Domain] Fair Value Measurement [Domain] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Fair Value Estimate of Fair Value Measurement [Member] Book and estimated fair values of financial instruments Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Debt obligations, net Earnings Per Share [Abstract] Income (loss) from continuing operations Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest Net (income) loss attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Preferred dividends Preferred Stock Dividends, Income Statement Impact Income (loss) from continuing operations attributable to iStar Inc. and allocable to common shareholders for basic earnings per common share Net Income (Loss) from Continuing Operations Available to Common Shareholders, Basic Add: Effect of Series J convertible perpetual preferred stock Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities Income (loss) from continuing operations attributable to iStar Inc. and allocable to common shareholders for diluted earnings per common share Net Income (Loss) from Continuing Operations Available to Common Shareholders, Diluted Land and Development Land and Development [Text Block] Land and Development [Text Block] Allowance for Loan Losses [Roll Forward] Allowance for Loan Losses [Roll Forward] Reserve for loan losses at beginning of period Financing Receivable, Allowance for Credit Losses Charge-offs Allowance for Loan Losses Write-Offs Reflects the amount of loans that have been removed, or charged off, from both loan receivables and the reserve for credit losses, typically because they are considered to be not salvageable or have been purchased by unconsolidated collection entities. Reserve for loan losses at end of period Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Gross contributions made by the Company Defined Contribution Plan, Cost Earnings Per Share Earnings Per Share [Text Block] Schedule of derivative financial instruments on Consolidated Statements of Operations Derivative Instruments, Gain (Loss) [Table Text Block] Investments, All Other Investments [Abstract] Schedule of Equity Method Investments [Table] Schedule of Equity Method Investments [Table] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Pronouncement, Early Adoption [Axis] New Accounting Principles, Early Adoption [Domain] New Accounting Principles, Early Adoption [Domain] New Accounting Pronouncement, Early Adoption, Effect New Accounting Pronouncement, Early Adoption, Effect [Member] Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Accounting Standards Update 2017-05 Accounting Standards Update 2017-05 [Member] Accounting Standards Update 2017-05 [Member] Title of Individual [Axis] Title of Individual [Axis] Relationship to Entity [Domain] Relationship to Entity [Domain] Chief Executive Officer and Chief Financial Officer Chief Executive Officer and Chief Financial Officer [Member] Chief Executive Officer and Chief Financial Officer [Member] Plan Name [Axis] Plan Name [Axis] Plan Name [Domain] Plan Name [Domain] 10b5-1 Plan 10b5-1 Plan [Member] 10b5-1 Plan [Member] 2017 Secured Financing 2017 Secured Financing [Member] 2017 Secured Financing [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Ground Net Lease Business Ground Net Lease Business [Member] Ground Net Lease Business [Member] Consolidated Entities [Axis] Consolidated Entities [Axis] Consolidated Entities [Domain] Consolidated Entities [Domain] Wholly-owned Subsidiary Subsidiaries [Member] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Safety, Income and Growth, Inc. Safety, Income and Growth, Inc. [Member] Safety, Income and Growth, Inc. [Member] Sale of Stock [Axis] Sale of Stock [Axis] Sale of Stock [Domain] Sale of Stock [Domain] Private Placement Private Placement [Member] IPO IPO [Member] Investment, Name [Axis] Investment, Name [Axis] Investment, Name [Domain] Investment, Name [Domain] Net lease venture iStar Net Lease I LLC [Member] iStar Net Lease I LLC [Member] Other real estate equity investments Other Real Estate Equity Investments [Member] Other Real Estate Equity Investments [Member] Ground Lease Ground Lease [Member] Ground Lease [Member] Great Oaks Great Oaks [Member] Great Oaks [Member] Marina Palms Marina Palms, LLC [Member] Marina Palms, LLC [Member] Marine Palms North Tower Marine Palms, LLC, North Tower [Member] Marine Palms, LLC, North Tower [Member] Marine Palms South Tower Marine Palms, LLC, South Tower [Member] Marine Palms, LLC, South Tower [Member] Newly formed unconsolidated entity Newly Formed Unconsolidated Entity [Member] Newly Formed Unconsolidated Entity [Member] Income Statement Location [Axis] Income Statement Location [Axis] Income Statement Location [Domain] Income Statement Location [Domain] Other income Other Income [Member] Operating Properties Leasehold First Mortgage Leasehold First Mortgage [Member] Leasehold First Mortgage [Member] Counterparty Name [Axis] Counterparty Name [Axis] Counterparty Name [Domain] Counterparty Name [Domain] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] iStar's ownership percentage Equity Method Investment, Ownership Percentage Partners' capital account, contributions (up to) Partners' Capital Commitment Partners' Capital Commitment Equity method investment, related party ownership percentage Equity Method Investment, Related Party Ownership Percentage Equity Method Investment, Related Party Ownership Percentage Equity method investment, related party promote fee percentage Equity Method Investment, Related Party Promote Fee Percentage Equity Method Investment, Related Party Promote Fee Percentage Equity method investment, partner ownership percentage Equity Method Investment, Partner Ownership Percentage Equity Method Investment, Partner Ownership Percentage Total assets carrying value Equity Method Investment, Summarized Financial Information, Assets Management fees revenue Management Fees Revenue Payments to acquire equity method investments Payments to Acquire Equity Method Investments Noncontrolling interest (as a percent) Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Contributions by majority shareholders Payments to Acquire Interest in Joint Venture Noncontrolling interest, ownership percentage by parent Noncontrolling Interest, Ownership Percentage by Parent Carrying value of assets Net proceeds from sales of real estate Proceeds from Sale of Real Estate Number of properties Number Of Properties Acquired Number Of Properties Acquired Gain from discontinued operations Discontinued Operation, Gain (Loss) from Disposal of Discontinued Operation, before Income Tax Retained earnings (deficit) Retained Earnings (Accumulated Deficit) Gain on sale of business Gain (Loss) on Disposition of Business Proceeds from issuance initial public offering Proceeds from Issuance Initial Public Offering Proceeds from issuance of private placement Proceeds from Issuance of Private Placement Payments of stock issuance costs Payments of Stock Issuance Costs Offering costs Stock Issuance Costs Stock Issuance Costs Number of shares purchased Common Stock Purchase Plan, Shares, Purchased in Period Common Stock Purchase Plan, Shares, Purchased in Period Aggregate value of common stock purchased Common Stock Purchase Plan, Amount Purchased in Period Common Stock Purchase Plan, Amount Purchased in Period Average share price (in dollars per share) Common Stock Purchase Plan, Average Share Price Common Stock Purchase Plan, Average Share Price Common stock purchase plan, number of plans Common Stock Purchase Plan, Number of Plans Common Stock Purchase Plan, Number of Plans Management fee, percent of equity below threshold Related Party Transaction, Management Fee, Percent of Equity Below Threshold Related Party Transaction, Management Fee, Percent of Equity Below Threshold Management fee, shareholders' equity threshold amount Related Party Transaction, Management Fee, Shareholders' Equity Threshold Amount Related Party Transaction, Management Fee, Shareholders' Equity Threshold Amount Management fee, percent of equity above threshold Related Party Transaction, Management Fee, Percent of Equity Above Threshold Related Party Transaction, Management Fee, Percent of Equity Above Threshold Management fees waived Management Fees Waived Management Fees Waived Reimbursement revenue waived Reimbursement Revenue Waived Reimbursement Revenue Waived Commitment to provide loan to lessee Related Party Transaction, Commitment to Extend Credit to Customer Related Party Transaction, Commitment to Extend Credit to Customer Loan term Debt Instrument, Term Amount of loan funded Related Party Transaction, Commitment to Extend Credit, Amount Funded Related Party Transaction, Commitment to Extend Credit, Amount Funded Lessor, operating lease, term of contract Lessor, Operating Lease, Term of Contract Number of units in real estate property to be built Number of Units in Real Estate Property to be Built Number of Units in Real Estate Property to be Built Real estate, leasehold improvement allowance Real Estate, Leasehold Improvement Allowance Real Estate, Leasehold Improvement Allowance Total gross carrying value of loans Loans Receivable Net of Deferred Income Reflects the aggregate gross carrying amount of all categories of loans held in portfolio, after deducting deferred income, but before deducting the allowance for losses on loans. Forward purchase contract, purchase agreement, amount Forward Purchase Contract, Purchase Agreement, Amount Forward Purchase Contract, Purchase Agreement, Amount Number of units Number of Units in Real Estate Property Number of units remaining for sale Number Of Units In Real Estate Property Available For Sale Number Of Units In Real Estate Property Available For Sale Equity method investments, carrying value Equity Method Investments Loan commitments Loans Commitments,Related Party Loans Commitments,Related Party Loans receivable, carrying value Loans Receivable, Related Party Loans Receivable, Related Party Interest income Interest Income, Related Party Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Series D, G and I Preferred Stock Series D, G, and I Preferred Stock [Member] Series D, G, and I Preferred Stock [Member] Preferred Stock Series J Statement [Line Items] Statement [Line Items] ASSETS Assets [Abstract] Real estate Real estate, at cost Real Estate Investment Property, Held for Use, Gross Real Estate Investment Property, Held for Use, Gross Less: accumulated depreciation Real Estate Investment Property, Accumulated Depreciation Real estate, net Cash and cash equivalents Cash and Cash Equivalents, at Carrying Value Accrued interest and operating lease income receivable, net Accrued Interest and Operating Lease Income Receivable Net This element represents interest, rents, ancillary and operating lease income earned but not yet received by the entity on its loans and other lending investments and net lease assets. Deferred operating lease income receivable, net Deferred Rent Receivables, Net Deferred expenses and other assets, net Deferred Expenses and Other Assets Net This element represents net amount of other deferred expenses and other assets capitalized at the end of the reporting period. LIABILITIES AND EQUITY Liabilities and Equity [Abstract] Liabilities: Liabilities [Abstract] Accounts payable, accrued expenses and other liabilities Accounts Payable and Accrued Liabilities Loan participations payable, net Loan Participations Payable, net Loan Participations Payable, net Total liabilities Liabilities Commitments and contingencies (refer to Note 11) Commitments and Contingencies Equity: Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] iStar Inc. shareholders' equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred Stock Preferred Stock, Value, Issued Common Stock, $0.001 par value, 200,000 shares authorized, 67,901 and 68,236 shares issued and outstanding as of March 31, 2018 and December 31, 2017, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Accumulated other comprehensive income (loss) (refer to Note 13) Total iStar Inc. shareholders' equity Stockholders' Equity Attributable to Parent Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest Total equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Total liabilities and equity Liabilities and Equity Schedule of assets and liabilities recorded at fair value on a recurring and non-recurring basis by levels Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Summary of changes in Level 3 available-for-sale securities reported at fair value Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Loan Participations Payable [Abstract] Loan Participations Payable [Abstract] Schedule of Participating Mortgage Loans Schedule of Participating Mortgage Loans [Table Text Block] Statement of Cash Flows [Abstract] Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to cash flows from operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Recovery of loan losses Impairment of assets Asset Impairment Charges Depreciation and amortization Depreciation, Depletion and Amortization Non-cash expense for stock-based compensation Share-based Compensation Amortization of discounts/premiums and deferred financing costs on debt obligations, net Amortization of Debt Issuance Costs and Discounts Amortization of discounts/premiums on loans and deferred interest on loans, net Amortization of Discounts or Premiums and Costs on Lending Investments, net Amortization of discounts/premiums and costs on loans, net Deferred interest on loans received Decrease (Increase) in Deferred Interest on Loans, Net Decrease (Increase) in Deferred Interest on Loans, Net Earnings from equity method investments Distributions from operations of other investments Proceeds from Equity Method Investment, Distribution Deferred operating lease income Straight Line Rent Income from sales of real estate Gain (Loss) on Sale of Properties, Cash Flow Impact Gain (Loss) on Sale of Properties, Cash Flow Impact Land development revenue in excess of cost of sales Loss on early extinguishment of debt, net Gains (Losses) on Extinguishment of Debt, Cash Flow Impact Amount represents the cash flow impact of the difference between the fair value of the payments made and the carrying amount of the debt at the time of its extinguishment. Other operating activities, net Other Operating Activities, Cash Flow Statement Changes in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Changes in accrued interest and operating lease income receivable Increase (Decrease) in Accrued Interest and Operating Lease and Income Receivable This element represents net change during the reporting period in accrued interest income and operating lease income receivable earned but not yet received. Changes in deferred expenses and other assets, net Increase (Decrease) in Prepaid Expense and Other Assets Changes in accounts payable, accrued expenses and other liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities Cash flows provided by (used in) operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Originations and fundings of loans receivable, net Payments to Acquire Notes Receivable Capital expenditures on real estate assets Payments for Capital Improvements Capital expenditures on land and development assets Repayments of and principal collections on loans receivable and other lending investments, net Proceeds from Principal Repayments on Portfolio of Assets Proceeds from Principal Repayments on Portfolio of Assets Net proceeds from sales of land and development assets Proceeds from sale of land development Proceeds from sale of land development Distributions from other investments Proceeds from Equity Method Investment, Distribution, Return of Capital Contributions to and acquisition of interest in other investments Other investing activities, net Payments for (Proceeds from) Other Investing Activities Cash flows provided by investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Borrowings from debt obligations and convertible notes Proceeds from Issuance of Debt Repayments and repurchases of debt obligations Preferred dividends paid Payments of Ordinary Dividends, Preferred Stock and Preference Stock Repurchase of stock Payments for Repurchase of Common Stock Payments for deferred financing costs Payments of Financing Costs Payments for withholding taxes upon vesting of stock-based compensation Payments Related to Tax Withholding for Share-based Compensation Payments for debt prepayment or extinguishment costs Payment for Debt Extinguishment or Debt Prepayment Cost Other financing activities, net Proceeds from (Payments for) Other Financing Activities Cash flows provided by (used in) financing activities Net Cash Provided by (Used in) Financing Activities Effect of exchange rate changes on cash Effect of Exchange Rate on Cash and Cash Equivalents Changes in cash, cash equivalents and restricted cash Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Cash, cash equivalents and restricted cash at beginning of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at end of period Supplemental disclosure of non-cash investing and financing activity: Supplemental Cash Flow Elements [Abstract] Fundings and repayments of loan receivables and loan participations, net Funding (Repayments) For Financial Assets And Liabilities Funding (Repayments) For Financial Assets And Liabilities Accounts payable for capital expenditures on real estate assets Capital Expenditures Incurred but Not yet Paid on Real Estate Assets Capital Expenditures Incurred but Not yet Paid on Real Estate Assets Acquisitions of land and development assets through foreclosure Real Estate Owned, Transfer to Real Estate Owned Profit sharing arrangement Profit Sharing Payable1 Profit Sharing Payable1 Financing provided on sales of land and development assets, net Receivable for sales proceeds Receivable for sales proceeds Interest Expense Interest Expense [Member] Earnings from equity method investments Earnings from Equity Method Investments [Member] Earnings from Equity Method Investments [Member] Reclassification of (gains)/losses on cash flow hedges into earnings upon realization Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Land and Land Development Asset Land and Land Development Assets [Member] Land and Land Development Assets [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring basis Fair Value, Measurements, Recurring [Member] Non-recurring basis Fair Value, Measurements, Nonrecurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Quoted market prices in active markets (Level 1) Fair Value, Inputs, Level 1 [Member] Significant other observable inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Significant unobservable inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Assets and liabilities recorded at fair value Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Impaired real estate Impaired Other Real Estate Owned Fair Value Disclosure This element represents impaired OREOs held by the Company as of the end of the reporting period that are valued by the entity at fair value on the balance sheet date. Impaired real estate available and held for sale Impaired Real Estate Held-for-Sale, Fair Value Disclosure Impaired Real Estate Held-for-Sale, Fair Value Disclosure Impaired land and development Impaired Land and Development, Fair Value Disclosure Impaired Land and Development, Fair Value Disclosure Discount rate Fair Value Inputs, Discount Rate Estimated sales period Fair Value Inputs, Estimated Sales Period Fair Value Inputs, Estimated Sales Period Land and land development assets land and land improvements [Table Text Block] [Table Text Block] for land and land improvements [Table] Other Assets and Other Liabilities [Abstract] -- None. No documentation exists for this element. -- Schedule of deferred expenses and other assets, net Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Table Text Block] Schedule of accounts payable, accrued expenses and other liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Investment [Table] Investment [Table] Held for Sale Reclassification [Axis] Held for Sale Reclassification [Axis] Held for Sale Reclassification [Axis] Held for Sale Reclassification [Domain] Held for Sale Reclassification [Domain] [Domain] for Held for Sale Reclassification [Axis] Held-for-Sale, Impending Contract to Sell Condominiums Held-for-Sale, Impending Contract to Sell Condominiums [Member] Held-for-Sale, Impending Contract to Sell Condominiums [Member] Held-for-Sale, Change in Business Strategy Held-for-Sale, Change in Business Strategy [Member] Held-for-Sale, Change in Business Strategy [Member] Investment [Line Items] Investment [Line Items] Impairment of assets Real Estate, Type of Property [Axis] Real Estate, Type of Property [Axis] Real Estate [Domain] Real Estate [Domain] Land Acquisition Type [Axis] Acquisition Type [Axis] Acquisition Type [Axis] Acquisition Type [Domain] Acquisition Type [Domain] Acquisition Type [Domain] Foreclosure Real Estate Acquired in Satisfaction of Debt [Member] Fair value of assets acquired Fair Value of Assets Acquired Number of land parcels sold Number of Land Parcels Sold Number of Land Parcels Sold Notes receivable issued for sale of land Increase (Decrease) in Notes Receivables Proceeds from collection of notes receivable Proceeds from Collection of Notes Receivable Land development cost of sales Treasury stock, shares, acquired (in shares) Stock Repurchased and Retired During Period, Shares Treasury stock value acquired including acquisition costs Common Stock Value Acquired Including Acquisition Costs Common Stock Value Acquired Including Acquisition Costs Treasury stock acquired, average cost per share (in dollars per share) Common Stock Acquired, Average Cost Per Share Common Stock Acquired, Average Cost Per Share Available repurchase of common stock, authorized amount (up to) Stock Repurchase Program, Remaining Authorized Repurchase Amount Schedule of other investments and its proportionate share of results for equity method investments Equity Method Investments [Table Text Block] Summarized investee financial information Equity Method Investments, Summarized Financial Information [Table Text Block] [Table Text Block] for Equity Method Investments, Summarized Financial Information [Table] Other Investments Other Investments [Text Block] This element represents the disclosures for equity method investments, cost method investments, and marketable securities. Business and Organization Business and Organization [Text Block] This element represents nature of an entity's business, the major products or services it sells or provides and its principal markets. It also discloses background of the entity. Schedule of the Company's loans and other lending investments by class Schedule of Loans and Other Lending Investments [Table Text Block] Tabular disclosure of loans and other lending investments by class. Includes the gross carrying value of a loan by class, reserve for loan losses, and the net carrying value as of the Balance Sheet date. Schedule of changes in the Company's reserve for loan losses Allowance for Credit Losses on Financing Receivables [Table Text Block] Schedule of recorded investment in loans and associated reserve for loan losses Schedule of Investment in Loans and Associated Reserve for Loan Losses [Table Text Block] Tabular disclosure of the Company's recorded investment in loans and the associated reserve for loan losses. Schedule of investment in performing loans, presented by class and by credit quality, as indicated by risk rating Financing Receivable Credit Quality Indicators [Table Text Block] Schedule of recorded investment in loans, aged by payment status and presented by class Past Due Financing Receivables [Table Text Block] Schedule of recorded investment in impaired loans, presented by class Impaired Financing Receivables [Table Text Block] Schedule of average recorded investment in impaired loans and interest income recognized, presented by class Impaired Financing Receivables Average Recorded Investment and Interest Income Recognized [Table Text Block] Tabular disclosure by class of the average recorded investment in impaired loans and the related interest income recognized. Schedule of other lending investments - securities Marketable Securities [Table Text Block] Schedule of contractual maturities of the Company's securities Investments Classified by Contractual Maturity Date [Table Text Block] Liquidation preference (in dollars per share) Common Stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common Stock, shares authorized (in shares) Common Stock, Shares Authorized Common Stock, shares issued (in shares) Common Stock, Shares, Issued Common Stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Investment across a range of real estate sectors over the past two decades (more than) Real Estate Investment Real Estate Investment Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Accounts, Notes, Loans and Financing Receivable [Line Items] Reserves for loan losses Total loans receivable, net Other lending investments—securities Held-to-Maturity and Available-for-sale Securities This item represents investments in debt securities which are categorized as held-to-maturity and securities classified as available for sale. Total loans receivable and other lending investments, net Document and Entity Information [Abstract] -- None. No documentation exists for this element. -- Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Document Type Document Type Document Period End Date Document Period End Date Amendment Flag Amendment Flag Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Equity Equity Related Disclosure [Text Block] This element includes disclosures of Equity related items, including common stock, preferred stock, dividend requirements, treasury stock and accumulated other comprehensive income. Schedule of Real Estate Properties [Table] Schedule of Real Estate Properties [Table] Real Estate Assets Held-for-Sale Real Estate Asses Held-for-Sale [Member] Real Estate Asses Held-for-Sale [Member] Residential Real Estate Residential Real Estate [Member] Residential Real Estate, Type of Property [Axis] Residential Real Estate, Type of Property [Axis] Residential Real Estate, Type of Property [Axis] Residential Real Estate, Type of Property [Domain] Residential Real Estate, Type of Property [Domain] Residential Real Estate, Type of Property [Domain] Master Planned Community Master Planned Community [Member] Master Planned Community [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Real Estate Available and Held for Sale Real Estate Available and Held for Sale [Member] Real Estate Available and Held for Sale [Member] Real Estate Properties [Line Items] Real Estate Properties [Line Items] Other liabilities Other Liabilities Accrued expenses Accrued Liabilities Other than Interest Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include property accounts payable, legal liabilities, loan costs, general and administrative liabilities, but exclude interest. Accrued interest payable Interest Payable Intangible liabilities, net Below Market Lease, Net Accounts payable, accrued expenses and other liabilities Developer fee payable Profit Sharing Payable Profit Sharing Payable Special assessment bond Special Assessment Bond Below market lease, accumulated amortization Below Market Lease, Accumulated Amortization Amortization of below market lease Amortization of Below Market Lease Debt Obligations, net Debt Disclosure [Text Block] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Restricted Stock Units (RSUs) [Member] Restricted Stock Units (RSUs) [Member] 2013-2014 Performance Incentive Plan 2013-2014 Performance Incentive Plan [Member] 2013-2014 Performance Incentive Plan [Member] 2015-2016 Performance Plan 2015-2016Performance Plan [Member] 2015-2016Performance Plan [Member] 2017-2018 Performance Incentive Plan 2017-2018 Performance Incentive Plan [Member] 2017-2018 Performance Incentive Plan [Member] All Performance Incentive Plans All performance incentive plans [Member] All performance incentive plans [Member] Common Stock Subject to Sales Restriction Common Stock Subject to Sales Restriction [Member] Common Stock Subject to Sales Restriction [Member] Long-term Incentive Plan 2009 Long-term Incentive Plan 2009 [Member] Represents information pertaining to 2009 Long-Term Incentive Plan of the entity. Schedule of Share-based Compensation Arrangement by Title of Individual [Axis] Schedule of Share-based Compensation Arrangement by Title of Individual [Axis] Reflects the pertinent provisions pertaining to equity-based compensation arrangement, by individual. Schedule of Share-based Compensation Arrangement by Title of Individual with Relationship to Entity [Domain] Schedule of Share-based Compensation Arrangement by Title of Individual with Relationship to Entity [Domain] Title of the individual (or the nature of the entity's relationship with the individual) who is party to the equity-based compensation arrangement. Employees Employees [Member] Represent employees of the entity. Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Number of Points Outstanding [Roll Forward] Number of Points Outstanding [Roll Forward] Number of Points Outstanding [Roll Forward] Points at beginning of period Number of Points Outstanding Number of Points Outstanding Granted (points) Number of Points Granted Number of Points Granted Forfeited (points) Number of Points Forfeited Number of Points Forfeited Points at end of period Preferred return hurdle preferred return preferred return Compensation value of total distribution Points Distribution During Period, Value Points Distribution During Period, Value Cash portion of points distribution Points Distribution During Period, Value, Cash Points Distribution During Period, Value, Cash Number of shares issued in points distribution Points Distribution During Period, Shares, Number of Shares Points Distribution During Period, Shares, Number of Shares Value of shares issued in points distribution Points Distribution During Period, Value, Shares Points Distribution During Period, Value, Shares Fair value of shares in points distribution Points Distribution During Period, Shares, Fair Value of Shares Issued Points Distribution During Period, Shares, Fair Value of Shares Issued Number of shares issued, net of tax withholding in points distribution Points Distribution During Period, Shares, Number of Shares Issued Net of Tax Withholding Points Distribution During Period, Shares, Number of Shares Issued Net of Tax Withholding Shares available for issuance Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Vested, number of shares Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period Restricted shares awarded Restricted Stock, Shares Issued Net of Shares for Tax Withholdings Sale restriction period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Sale Restriction Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Sale Restriction Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Non-vested at beginning of period (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Forfeited Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Non-vested at end of period (in shares) Unrecognized compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Weighted-average period to recognize the unrecognized compensation cost Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Statement of Stockholders' Equity [Abstract] Net income (loss) attributable to redeemable noncontrolling interest Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Series J convertible perpetual preferred stock Joint venture shares Joint Venture Shares [Member] Incremental common shares attributable to joint venture shares that were not included in diluted earnings per share (EPS) because to do so would increase EPS amounts or decrease loss per share amounts during the period presented. Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Anti-dilutive shares (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Threshold consecutive trading days Debt Instrument, Convertible, Threshold Consecutive Trading Days Schedule of Operating Lease Allowance for Doubtful Accounts [Table] Schedule of Operating Lease Allowance for Doubtful Accounts [Table] Schedule of Operating Lease Allowance for Doubtful Accounts [Table] Real Estate Tenant Receivables Real Estate Tenant Receivables [Member] Real Estate Tenant Receivables [Member] Deferred Operating Lease Deferred Operating Lease [Member] Deferred Operating Lease [Member] Schedule of Operating Lease Allowance for Doubtful Accounts [Line Items] Schedule of Operating Lease Allowance for Doubtful Accounts [Line Items] [Line Items] for Schedule of Operating Lease Allowance for Doubtful Accounts [Table] Allowance for doubtful accounts receivable Allowance for Doubtful Accounts Receivable Income Statement [Abstract] Revenues: Revenues [Abstract] Total revenues Revenues Costs and expenses: Costs and Expenses [Abstract] Interest expense Interest Expense Real estate expense Cost of Real Estate Revenue Land development cost of sales Costs of Real Estate Services and Land Sales Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction General and administrative General and Administrative Expense Other expense Total costs and expenses Costs and Expenses Income (loss) before earnings from equity method investments and other items Income (Loss) from Continuing Operations before Income (Loss) from Equity Method Investments and Other Items This element represents the income (loss) from continuing operations before income (loss) from equity method investments, gains (losses) on early extinguishment of debt, and other items. Loss on early extinguishment of debt, net Gain (Loss) on Extinguishment of Debt Earnings from equity method investments Income (loss) from continuing operations before income taxes Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income tax expense Income Tax Expense (Benefit) Income (loss) from continuing operations Net income (loss) Net (income) loss attributable to noncontrolling interests Net income (loss) attributable to iStar Inc. Net Income (Loss) Attributable to Parent Preferred dividends Preferred Stock Dividends and Other Adjustments Net income (loss) allocable to common shareholders Net Income (Loss) Available to Common Stockholders, Basic Per common share data: Earnings Per Share, Basic and Diluted [Abstract] Income (loss) attributable to iStar Inc. from continuing operations: Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent [Abstract] Basic (in dollars per share) Income (Loss) from Continuing Operations, Per Basic Share Diluted (in dollars per share) Income (Loss) from Continuing Operations, Per Diluted Share Net income (loss) attributable to iStar Inc.: Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Weighted average number of common shares: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Weighted average common shares outstanding for diluted earnings per common share Weighted Average Number of Shares Outstanding, Diluted Equity-based compensation Number of ground net leases Number of Net Lease Assets Number of Net Lease Assets Number of master leases Number of Master Lease Assets Number of Master Lease Assets Number of properties covered under master lease agreement Debt Instrument, Number of Properties Covered Under Master Lease Agreement Debt Instrument, Number of Properties Covered Under Master Lease Agreement Carrying value of properties Property, Plant and Equipment, Net Real estate equity investments Real Estate Investment [Member] Other strategic investments Other Strategic Investments [Member] Other Strategic Investments [Member] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Group Name [Domain] Disposal Group Name [Domain] Revenues Disposal Group, Including Discontinued Operation, Revenue Expenses Disposal Group, Including Discontinued Operation, Operating Expense Income sales of real estate Gains (Losses) on Sales of Investment Real Estate Income from discontinued operations Disposal Group, Including Discontinued Operation, Operating Income (Loss) Cash flows provided by discontinued operations, operating activities Cash Provided by (Used in) Operating Activities, Discontinued Operations Cash flows used in discontinued operations, investing activities Cash Provided by (Used in) Investing Activities, Discontinued Operations Equity Method Investments, Summarized Financial Information [Table] Equity Method Investments, Summarized Financial Information [Table] Equity Method Investments, Summarized Financial Information [Table] Equity Method Investments, Summarized Financial Information [Line Items] Equity Method Investments, Summarized Financial Information [Line Items] [Line Items] for Equity Method Investments, Summarized Financial Information [Table] Revenues Equity Method Investment, Summarized Financial Information, Revenue Expenses Equity Method Investment, Summarized Financial Information, Cost of Sales Net Income Attributable to Parent Entities Equity Method Investment, Summarized Financial Information, Net Income (Loss) Accounting Policies [Abstract] New Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Schedule of Financing Receivable, Allowance for Credit Losses [Table] Individually Evaluated for Impairment Individually Evaluated for Impairment [Member] Individually Evaluated for Impairment [Member] Financing Receivable, Allowance for Credit Losses [Line Items] Financing Receivable, Allowance for Credit Losses [Line Items] Loans Less: Reserve for loan losses Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment Less: Reserve for loan losses Less: Reserve for loan losses Total Financing Receivable, Net Unamortized discounts, premiums, deferred fees and costs, net (discount) or premium Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums Release of general reserve Interest receivable Interest Receivable Held-to-maturity and available-for-sale securities Other Assets and Other Liabilities Other Assets and Other Liabilities Disclosure [Text Block] This element may be used as a single block of text to encapsulate the entire disclosure for other assets and other liabilities including data and tables. Net Lease Residential Operating Properties Residential Operating Properties [Member] Residential Operating Properties [Member] Land, at cost Land and Land Improvements Buildings and improvements, at cost Investment Building and Building Improvements Less: accumulated depreciation Unsecured Credit Facilities Unsecured Credit Facilities [Member] Represents the unsecured credit facility of the entity. 2015 $325 Million Secured Revolving Credit Facility Secured Credit Facility Revolver Due March 2018 [Member] Secured Credit Facility Revolver Due March 2018 [Member] Minimum ratio of unencumbered assets to unsecured indebtedness (at least) Debt Instrument Covenant Ratio of Unencumbered Assets to Unsecured Indebtedness Represents the minimum ratio of encumbered assets to unsecured indebtedness required under the terms of the debt covenant. Debt instrument covenant multiple of minimum fixed charges on outstanding borrowings Debt Instrument, Covenant, Multiple of Minimum Fixed Charges on Outstanding Borrowings Debt Instrument, Covenant, Multiple of Minimum Fixed Charges on Outstanding Borrowings Multiple of the minimum collateral coverage on outstanding borrowings (at least) Debt Instrument Covenant Multiple of Minimum Collateral Coverage on Outstanding Borrowings Represents the multiple of the minimum collateral coverage on outstanding borrowings required under the terms of the debt covenant. Percentage of REIT taxable income permitted for distribution under debt covenants Debt Instrument Covenant Percentage of Taxable Income Permitted for Distribution if Reit classification is Maintained Represents the percentage of taxable income that is permitted for distribution, under the terms of the debt covenant, if the entity maintains its REIT qualification. Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] Interest Expense Other Expense Other Expense [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Derivative Contract [Domain] Derivative Contract [Domain] Interest rate swaps Interest Rate Swap [Member] Interest rate cap Interest Rate Cap [Member] Foreign exchange contracts Foreign Exchange Contract [Member] Hedging Designation [Axis] Hedging Designation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Designated as hedge Designated as Hedging Instrument [Member] Not designated as hedge Not Designated as Hedging Instrument [Member] Derivative financial instruments on consolidated statements of operations Derivative Instruments, Gain (Loss) [Line Items] Amount of Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Effective Portion) Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net Amount of Gain (Loss) Reclassified from Accumulated Other Comprehensive Income into Earnings (Effective Portion) Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net Amount of Gain (Loss) Recognized in Income For the Three Months Ended March 31, 2017 Derivative, Gain (Loss) on Derivative, Net Directors Director [Member] CSE and Restricted Stock Units CSE and Restricted Stock Award [Member] CSE and Restricted Stock Award [Member] Non-vested, outstanding (in shares) Aggregate intrinsic value for directors Share based Compensation Arrangement by Share based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value for Directors The aggregate intrinsic value of outstanding equity awards on equity-based plans excluding option plans for which the Company is contingently obligated to issue equity instruments or transfer assets to an director as calculated by applying the disclosed pricing methodology. Reconciliation of segment profit (loss) to income (loss) from continuing operations Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract] Segment profit Add: Recovery of loan losses Less: Impairment of assets Segment Asset Impairment Charges Segment Asset Impairment Charges Less: Stock-based compensation expense Less: Depreciation and amortization Segment Depreciation and Amortization Segment Depreciation and Amortization Less: Income tax expense Segment Income Tax (Benefit) Segment Income Tax (Benefit) Less: Loss on early extinguishment of debt, net Schedule of Variable Interest Entities [Table] Schedule of Variable Interest Entities [Table] Variable Interest Entities by Classification of Entity [Axis] Variable Interest Entities [Axis] Variable Interest Entity, Classification [Domain] Variable Interest Entity, Classification [Domain] Consolidated VIEs Variable Interest Entity, Primary Beneficiary, Aggregated Disclosure [Member] Unconsolidated VIEs Variable Interest Entity, Not Primary Beneficiary [Member] Variable interest entities Variable Interest Entity [Line Items] Variable interest entity, consolidated, carrying amount, assets Variable Interest Entity, Consolidated, Carrying Amount, Assets Variable interest entity, consolidated, carrying amount, liabilities Variable Interest Entity, Consolidated, Carrying Amount, Liabilities Carrying value of the investments Variable Interest Entity, Nonconsolidated, Carrying Amount, Assets and Liabilities, Net Variable interest entity unfunded commitment Variable Interest Entity Unfunded Commitment The amount of unfunded commitments that the entity has to the Variable Interest Entity. Loan Participations Payable, net Transfers and Servicing of Financial Assets [Text Block] Loan Participations Payable, net [Table] Loan Participations Payable, net [Table] Loan Participations Payable, net [Table] Loan Participations Payable, net [Line Items] Loan Participations Payable, net [Line Items] [Line Items] for Loan Participations Payable, net [Table] Loan participations payable, gross Loan Participations Payable, gross Loan Participations Payable, gross Loan participations payable, net Number of loan participations payable Transfers and Servicing of Financial Liabilities, Number of Instruments Transfers and Servicing of Financial Liabilities, Number of Instruments Schedule of Impaired Financing Receivable [Table] Schedule of Impaired Financing Receivable [Table] Impaired Loans Related Allowance [Axis] Impaired Loans Related Allowance [Axis] Attributes of impaired loans classified as impaired with or without specific allowance related to the loans, by class of financial receivable. Impaired Loans Related Allowance [Domain] Impaired Loans Related Allowance [Domain] Represents a subset of a class of impaired loans that have or do not have the specific allowances related to the impaired receivables. With no related allowance recorded Receivables Without Allowance [Member] Receivables Without Allowance [Member] With an allowance recorded Receivables With Allowance [Member] Receivables With Allowance [Member] Financing Receivable, Impaired [Line Items] Financing Receivable, Impaired [Line Items] Recorded Investment Impaired Financing Receivable, Recorded Investment Unpaid Principal Balance Impaired Financing Receivable, Unpaid Principal Balance Related Allowance Impaired Financing Receivable, Related Allowance Average Recorded Investment Impaired Financing Receivable, Average Recorded Investment Interest Income Recognized Impaired Financing Receivables Interest Income Cash or Accrual Method The interest income recognized on a cash-basis or accrual method of accounting during the time within that period that the financing receivables were impaired. Operating Lease Income Operating Lease Income [Member] Operating Lease Income [Member] Tenant reimbursements Tenant Reimbursements New Accounting Pronouncement, Early Adoption [Table] New Accounting Pronouncement, Early Adoption [Table] Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Adjustment [Member] Scenario, Adjustment [Member] Accounting Standards Update 2016-15 Accounting Standards Update 2016-15 [Member] Accounting Standards Update 2016-18 Accounting Standards Update 2016-18 [Member] New Accounting Pronouncement, Early Adoption [Line Items] New Accounting Pronouncement, Early Adoption [Line Items] Increase to cash flows provided by operating activities Decrease to cash flows provided by investing activities Restricted cash included in deferred expenses and other assets, net Restricted Cash and Cash Equivalents Total cash, cash equivalents and restricted cash reported in the consolidated statements of cash flows Total assets Total equity Reconciliation of income (loss) from continuing operations used in the basic and diluted EPS calculations Schedule of Income (Loss) from Continuing Operations Used in Basic and Diluted Earnings Per Share Calculations [Table Text Block] Tabular disclosure of the reconciliation of income (loss) from continuing operations used in the basic and diluted EPS calculations. Schedule of earnings per share allocable to common shares and HPU shares Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of anti-dilutive shares Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of iPip Activity Schedule of Other Share-based Compensation, Activity [Table Text Block] Schedule of Restricted Stock Units Activity Schedule of Nonvested Restricted Stock Units Activity [Table Text Block] Real Estate Real Estate Disclosure [Text Block] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Preferred Stock Preferred Stock [Member] Common Stock at Par Common Stock [Member] Additional Paid-In Capital Additional Paid-in Capital [Member] Retained Earnings (Deficit) Retained Earnings [Member] Accumulated Other Comprehensive Income (Loss) AOCI Attributable to Parent [Member] Noncontrolling Interests Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance Dividends declared—preferred Dividends, Preferred Stock, Cash Issuance of stock/restricted stock unit amortization, net Issuance of Stock and Restricted Stock Unit Amortization Net Value of stock related to restricted stocks awards issued during the period and the amortization of restricted stock units and other restricted stock activity. Net income (loss) for the period Profit (Loss) Adjusted for Income (Loss) Attributable to Redeemable Noncontrolling Interest The consolidated profit or loss for the period including the portion attributable to the noncontrolling interest, net of income taxes and income (loss) attributable to redeemable noncontrolling interest. Change in accumulated other comprehensive income Other Comprehensive Income (Loss), Net of Tax, Excluding Effect of Adoption of New Accounting Pronouncement Other Comprehensive Income (Loss), Net of Tax, Excluding Effect of Adoption of New Accounting Pronouncement Change in accumulated other comprehensive income Repurchase of stock Stock Repurchased During Period, Value Contributions from noncontrolling interests Noncontrolling Interest, Increase from Subsidiary Equity Issuance Impact from adoption of new accounting standards (refer to Note 3) Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect Tax Cuts and Jobs Act of 2017, Reclassification from AOCI to Retained Earnings, Tax Effect Change in additional paid in capital attributable to redeemable noncontrolling interest Adjustments to Additional Paid in Capital, Other Ending Balance Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] Schedule of Financing Receivable, Recorded Investment, Credit Quality Indicator [Table] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Axis] External Credit Rating by Grouping [Domain] External Credit Rating by Grouping [Domain] Real Estate Finance Performing Financial Instruments [Member] Recorded Investments in loans, presented by class and by credit quality, as indicated by risk rating Financing Receivable, Recorded Investment [Line Items] Weighted Average Risk Ratings Weighted Average Risk Ratings Represents the weighted average risk rating of the instrument. Stock-Based Compensation Plans and Employee Benefits Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Line of Credit Facility [Table] Line of Credit Facility [Table] Other Expense Maximum Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Number of properties collateralizing loan Debt Instrument, Number of Properties Collateralizing Loan Debt Instrument, Number of Properties Collateralizing Loan Loss on early extinguishment of debt, net Equity capitalization amount, at least Guarantor Obligations, Recourse Triggering Event, Equity Capitalization Amount Guarantor Obligations, Recourse Triggering Event, Equity Capitalization Amount Net worth, at least Guarantor Obligations, Recourse Triggering Event, Net Assets Guarantor Obligations, Recourse Triggering Event, Net Assets Percentage of par credit facilities were issued at Line of Credit Facility Issue Price as Percentage of Principal Amount Represents the percentage of principal amount used in the computation of issue price for the line of credit facility. Aggregate price reduction (as a percent) Debt Instrument, Price Reduction, Percent Debt Instrument, Price Reduction, Percent Required quarterly principal payment (as a percent) Debt Instrument, Periodic Principal Payment, Percent Debt Instrument, Periodic Principal Payment, Percent Line of credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Commitment fee percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Repayments of credit facility Repayments of Lines of Credit Earnings allocable to common shares: Share-based Compensation, Allocation and Classification in Financial Statements [Abstract] Numerator for basic earnings per share: Net Income (Loss) Available to Common Stockholders, Basic [Abstract] Income (loss) from continuing operations attributable to iStar Inc. and allocable to common shareholders Income from discontinued operations Net Income (Loss) from Discontinued Operations Available to Common Shareholders, Basic Numerator for diluted earnings per share: Net Income (Loss) Available to Common Stockholders, Diluted [Abstract] Income (loss) from continuing operations attributable to iStar Inc. and allocable to common shareholders Income from discontinued operations Net Income (Loss) from Discontinued Operations Available to Common Shareholders, Diluted Net income (loss) attributable to iStar Inc. and allocable to common shareholders Net Income (Loss) Available to Common Stockholders, Diluted Denominator for basic and diluted earnings per share: Denominator for Basic and Diluted Earnings Per Share or Hpu Share [Abstract] -- None. No documentation exists for this element. -- Weighted average common shares outstanding for basic earnings per common share (in shares) Add: Effect of assumed shares issued under treasury stock method for restricted stock units (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Add: Effect of series J convertible perpetual preferred stock (in shares) Incremental Common Shares Attributable to Dilutive Effect of Conversion of Preferred Stock Weighted average common shares outstanding for diluted earnings per common share (in shares) Basic earnings per common share: Income (loss) from continuing operations attributable to iStar Inc. and allocable to common shareholders (in dollars per share) Income (loss) from discontinued operations (in dollars per share) Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Basic Share Net income (loss) attributable to iStar Inc. and allocable to common shareholders (in dollars per share) Diluted earnings per common share: Earnings Per Share, Diluted [Abstract] Income (loss) from continuing operations attributable to iStar Inc. and allocable to common shareholders (in dollars per share) Income from discontinued operations (in dollars per share) Discontinued Operation, Income (Loss) from Discontinued Operation, Net of Tax, Per Diluted Share Net income (loss) attributable to iStar Inc. and allocable to common shareholders (in dollars per share) Schedule of New Accounting Pronouncements and Changes in Accounting Principles Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block] Schedule of cumulative redeemable and convertible perpetual preferred stock outstanding by series Schedule of Stock by Class [Table Text Block] Accumulated other comprehensive income (loss) reflected in the Company's shareholders' equity Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Gain (loss) recognized in accumulated other comprehensive income Derivative Instruments, Gain Recognized in Other Comprehensive Income (Loss), Effective Portion Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Schedule of Operating Leased Assets [Table] Schedule of Operating Leased Assets [Table] Depreciation and Amortization Depreciation and Amortization [Member] Depreciation and Amortization [Member] Operating Leased Assets [Line Items] Operating Leased Assets [Line Items] Other receivables Other Receivables Intangible assets, net Finite-Lived Intangible Assets, Net Other assets Other Assets Restricted cash Leasing costs, net Deferred Costs, Leasing, Net Corporate furniture, fixtures and equipment, net Furniture Fixtures, Leasehold Improvements and Software Costs, Net Furniture Fixtures, Leasehold Improvements and Software Costs, Net Deferred financing fees, net Debt Issuance Costs, Net Deferred expenses and other assets, net Intangible assets, accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Amortization of above market lease Amortization of Above Market Lease and Lease Incentive Asset Amortization of Above Market Lease and Lease Incentive Asset Amortization of intangible assets Amortization of Intangible Assets Accumulated amortization on leasing costs Deferred Costs, Leasing, Accumulated Amortization Accumulated depreciation on corporate furniture, fixtures and equipment Accumulated Depreciation Furniture Fixtures and Leasehold Improvements The cumulative amount of depreciation, related to leasehold improvements, corporate furniture, fixtures and equipment that has been recognized in the income statement. Schedule of financial measures for each segment based on which performance is evaluated Schedule of Segment Reporting Information, by Segment [Table Text Block] Reconciliation of segment profit to income (loss) Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block]