Loans Receivable, Net - Additional Information (Detail) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2022 USD ($) loan SecurityLoan	Dec. 31, 2021 USD ($) loan SecurityLoan	Dec. 31, 2022 USD ($) loan SecurityLoan	Dec. 31, 2021 USD ($) loan SecurityLoan	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average risk rating on loan exposure	2.8	2.8	2.8	2.8
Increase in CECL reserve			$ 201,458	$ (34,443)
CECL reserve	$ 326,137	$ 124,679	$ 326,137	$ 124,679	$ 173,549
Number of loans | SecurityLoan	203	188	203	188
Net book value	$ 24,691,743	$ 21,878,338	$ 24,691,743	$ 21,878,338
Outstanding principal balance	25,017,880	22,003,017	25,017,880	22,003,017	16,572,715	$ 16,164,801
Principal charge-offs			0	14,427	0
Reversal of remaining CECL reserve			(211,505)	39,864	(167,653)
Loans held	$ 26,810,281	$ 23,669,111	$ 26,810,281	$ 23,669,111
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	80	75	80	75
Loans held	$ 6,330,153	$ 5,771,517	$ 6,330,153	$ 5,771,517
Impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in CECL reserve			134,904	(360)
CECL reserve	$ 189,778	54,874	189,778	54,874	$ 69,661
Impaired loans | Four Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in CECL reserve			$ 134,900
Number of loans | loan	4		4
Net book value	$ 644,300		$ 644,300
Interest income	11,300
Impaired loans | Five Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
CECL reserve	$ 189,800		$ 189,800
Number of loans | loan	5		5
Net book value	$ 929,100		$ 929,100
Impaired loans | One Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
CECL reserve		$ 54,900		$ 54,900
Number of loans | loan		1		1
Net book value		$ 284,800		$ 284,800
Income recorded on loan			0	0
Joint Venture | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held	795,600	746,900	795,600	746,900
Office Asset In New York City
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	193,600		193,600
Additional commitments			8,200
Multifamily Properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance		37,500		$ 37,500
Multifamily Asset in New York City
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in CECL reserve		14,800
Principal charge-offs		14,400
Reversal of remaining CECL reserve		$ 360
Loans accounted under cost-recovery method	38,200		38,200
Hospitality Asset in New York City
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	$ 286,300		$ 286,300