Corporate Indebtedness - Schedule of Junior Subordinated Deferrable Interest Debentures and Principal Maturities (Details)	1 Months Ended	3 Months Ended
	Jun. 30, 2005 USD ($)	Mar. 31, 2026 USD ($) quarter
Principal Repayments and Joint Venture Debt
Remaining 2026		$ 655,148,000
2027		1,236,390,000
2028		284,438,000
2029		189,200,000
2030		0
Thereafter		2,409,107,000
Total principal repayments		$ 4,774,283,000
Trust Preferred Securities
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 100,000,000.0
Interest rate added to base rate (as a percent)		0.26%
Interest payment deferment, number of consecutive quarters | quarter		8
Due from joint ventures
Principal Repayments and Joint Venture Debt
Remaining 2026		$ 1,076,993,000
2027		1,453,918,000
2028		555,449,000
2029		0
2030		840,000,000
Thereafter		2,071,051,000
Total principal repayments		5,997,411,000
Due from joint ventures | 919 Third Avenue
Principal Repayments and Joint Venture Debt
Remaining 2026		255,000,000.0
Due from joint ventures | Principal
Principal Repayments and Joint Venture Debt
Remaining 2026		555,148,000
2027		936,390,000
2028		284,438,000
2029		189,200,000
2030		0
Thereafter		734,107,000
Total principal repayments		2,699,283,000
Due from joint ventures | Revolving Credit Facility
Principal Repayments and Joint Venture Debt
Remaining 2026		0
2027		0
2028		0
2029		0
2030		0
Thereafter		825,000,000
Total principal repayments		825,000,000
Due from joint ventures | Unsecured Term Loans
Principal Repayments and Joint Venture Debt
Remaining 2026		100,000,000
2027		300,000,000
2028		0
2029		0
2030		0
Thereafter		750,000,000
Total principal repayments		1,150,000,000
Due from joint ventures | Trust Preferred Securities
Principal Repayments and Joint Venture Debt
Remaining 2026		0
2027		0
2028		0
2029		0
2030		0
Thereafter		100,000,000
Total principal repayments		$ 100,000,000