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Business and Organization - Merger Transactions (Details) $ / shares in Units, $ in Millions			1 Months Ended
	Mar. 31, 2023 USD ($) director shares	Aug. 10, 2022 USD ($) $ / shares shares	Feb. 28, 2022 USD ($) shares
Merger
Number of directors from Old SAFE entity on new post-merger board \| director	3
Number of directors from iStar entity on new post-merger board \| director	2
Number of management members from both Old SAFE and iStar entities on new post-merger board \| director	2
Caret Units
Merger
Number of shares to be sold under purchase commitment related to merger \| shares			28,571
Expected proceeds from sale of shares under purchase commitment related to merger			$ 5.0
MSD Partners \| Caret Units
Merger
Number of shares to be sold under purchase commitment related to merger \| shares		100,000
Expected proceeds from sale of shares under purchase commitment related to merger		$ 20.0
Purchase price adjustment credit on the sale of shares	$ 0.6
Star Holdings
Merger
Stated interest on term loan	8.00%
Term on loan	4 years
Principal amount of term loan	$ 115.0
Star Holdings \| Affiliated entity
Merger
Term on loan	4 years
Annual management fee - Year 1	$ 25.0
Annual management fee - Year 2	15.0
Annual management fee - Year 3	10.0
Annual management fee - Year 4	$ 5.0
Annual management fee percent of gross book value, year five and thereafter	2.00%
Star Holdings
Merger
Cash received in spin off transaction	$ 50.0
Shares in Old SAFE received in spin off transaction \| shares	13,500,000
Star Holdings \| Morgan Stanley Bank
Merger
Bank debt	$ 140.0
Number of SAFE shares pledged as security on bank debt \| shares	13,500,000
Star Holdings \| SOFR \| Morgan Stanley Bank
Merger
Basis point spread on variable interest rate (percent)	3.00%
Star Holdings \| Spinco Manager \| Affiliated entity
Merger
Annual management fee - Year 1	$ 25.0
Annual management fee - Year 2	15.0
Annual management fee - Year 3	10.0
Annual management fee - Year 4	$ 5.0
Annual management fee percent of gross book value, year five and thereafter	2.00%
iStar Inc. \| MSD Partners
Merger
Number of shares to be sold under purchase commitment related to merger \| shares		5,405,406
Expected proceeds from sale of shares under purchase commitment related to merger		$ 200.0
Sale of stock, share price (in dollars per share) \| $ / shares		$ 37.00