Equity (Narrative) (Details)		1 Months Ended				3 Months Ended					12 Months Ended
	Dec. 01, 2021 shares	Sep. 30, 2021 USD ($) shares	Aug. 31, 2021 director	Feb. 28, 2021 USD ($)	Mar. 31, 2020 USD ($) employee	Dec. 31, 2021 USD ($) class $ / shares shares	Jun. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2019 USD ($) $ / shares shares	Mar. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) class $ / shares shares	Dec. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($) $ / shares	Feb. 29, 2020 USD ($)
Class of Stock [Line Items]
Number of classes of common stock | class						1					1
Proceeds from stock transaction		$ 192,300,000
Percentage of awards vested											12.00%
Percentage of awards forfeited											88.00%
Percentage of taxable income including capital gains to be distributed to qualify as REIT											100.00%
Minimum percentage of taxable income excluding capital gains to be distributed to qualify as REIT											90.00%
Cash dividends declared											$ 37,000,000.0	$ 33,200,000	$ 21,400,000
Dividends declared, per share (usd per share) | $ / shares											$ 0.67224	$ 0.6427	$ 0.618
Dividends, ordinary income amount (in dollars per share) | $ / shares													0.0699
Dividends, return of capital for tax reporting (in dollars per share) | $ / shares													$ 0.5421
Distribution payable to noncontrolling interest													$ 1,900,000
Distribution payable to noncontrolling interest, per investor unit (in dollars per share) | $ / shares													$ 0.15
Number of directors with affiliated trusts which hold CARET Units | director			2
Number of common shares issued in exchange for Caret Units | shares	2,546
ATM
Class of Stock [Line Items]
Common stock offering amount				$ 250,000,000.0
Number of shares issued in transaction | shares											12,881
Sale of stock, share price (in dollars per share) | $ / shares						$ 81.45					$ 81.45
Payments of stock issuance costs											$ 15,977
Consideration received, net of issuance costs											1,000,000.0
Aggregate purchase price remaining						$ 248,900,000					$ 248,900,000
Public Offering
Class of Stock [Line Items]
Number of shares issued in transaction | shares		2,530,000
Payment of financing and stock issuance costs		$ 8,000,000.0
Private Placement
Class of Stock [Line Items]
Proceeds from private placement offering		$ 50,000,000.0
Number of shares issued in transaction | shares		657,894
Performance Shares
Class of Stock [Line Items]
Capital appreciation aggregate distribution, percent									15.00%
Ownership percentage after transaction											85.00%
Awards with aggregate intrinsic value									$ 1,400,000
Amortization period											4 years
Number of CARET Units exchanged for common shares | shares	3,750
Restricted Stock Units (RSUs) | 2017 Equity Incentive Plan
Class of Stock [Line Items]
Issuance of common stock, net of amortization										$ 500,000
Stock issued during period, shares, issued for services | shares										25,000
Share price (in dollars per share) | $ / shares										$ 19.15
Manager | Performance Shares
Class of Stock [Line Items]
Awards with aggregate intrinsic value					$ 100,000									$ 500,000
Award vesting period											3 years
Employee of Manager
Class of Stock [Line Items]
Number of individuals receiving award grants | employee					1
Director | 2017 Equity Incentive Plan
Class of Stock [Line Items]
Issuance of common stock, net of amortization							$ 1,100,000	$ 1,000,000.0	$ 1,100,000
Share price (in dollars per share) | $ / shares							$ 69.86	$ 46.94
Stock issued (in shares) | shares							16,000	22,000
General and Administrative Expense | 2017 Equity Incentive Plan
Class of Stock [Line Items]
Share-based payment arrangement, expense											$ 1,300,000	$ 1,200,000	$ 1,200,000
General and Administrative Expense | Restricted Stock Units (RSUs) | 2017 Equity Incentive Plan
Class of Stock [Line Items]
Stock issued during period, shares, issued for services | shares										25,000
Capital shares reserved for future issuance (in shares) | shares						724,500					724,500
General and Administrative Expense | Manager | Performance Shares | Equity Plan
Class of Stock [Line Items]
Aggregate compensation cost											$ 500,000	$ 500,000	$ 400,000
General and Administrative Expense | Director | 2017 Equity Incentive Plan
Class of Stock [Line Items]
Share price (in dollars per share) | $ / shares									$ 27.19
Stock issued (in shares) | shares									40,000
iStar Inc.
Class of Stock [Line Items]
Common stock purchase plan, shares, purchased in period | shares						24,108					1,000,000.0
Common stock purchase plan, amount purchased in period						$ 1,800,000					$ 69,500,000
Common Stock purchase plan, average share price (in dollars per share) | $ / shares											$ 72.96
Percentage of ownership before transaction												64.60%
iStar Inc. | SAFE | Maximum
Class of Stock [Line Items]
Common stock voting rights, investor units voting power threshold						41.90%					41.90%