Loans Receivable, Net - Additional Information (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2023 USD ($) loan	Dec. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) security_loan	Dec. 31, 2023 USD ($) loan	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) security_loan	Dec. 31, 2022 USD ($) loan	Dec. 31, 2021 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average risk rating	3.0	3.0	3.0	3.0	3.0	3.0	2.9	2.9	2.9
Increase (decrease) in CECL reserve			$ 250,799				$ 201,458
CECL reserve	$ 576,936	$ 576,936	576,936	$ 576,936	$ 576,936	$ 576,936	326,137	$ 326,137	$ 326,137	$ 124,679
Number of loans				178	178			203	203
Net book value	23,210,076	23,210,076	23,210,076	$ 23,210,076	$ 23,210,076	23,210,076	24,691,743	$ 24,691,743	$ 24,691,743
Cash proceeds			53,000
Principal balance	23,787,012	23,787,012	23,787,012	23,787,012	$ 23,787,012	23,787,012	25,017,880	25,017,880	25,017,880	22,003,017
Number of loan modifications | loan					5
Loans held	24,971,028	$ 24,971,028	24,971,028	24,971,028	$ 24,971,028	$ 24,971,028	26,810,281	26,810,281	26,810,281
Payment Deferral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan					3
Aggregate amortized cost basis of loans			546,300
Percentage to aggregate loans receivable portfolio						2.30%
Payment Deferral, Loan One
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension term		1 year
Contributions to reserve account			2,000
Interest rate increase						5.11%
Payment Deferral, Loan Two
Accounts, Notes, Loans and Financing Receivable [Line Items]
Exit fee percentage						4.00%
Payment Deferral, Loan Three
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest rate increase						2.00%
Exit fee percentage						2.00%
Extended Maturity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan					2
Aggregate amortized cost basis of loans			434,500
Percentage to aggregate loans receivable portfolio						1.80%
Extended Maturity, Loan One
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension term		19 months
Contributions to reserve account			4,900
Interest rate reduction						2.74%
Repayment due by borrower at maturity period			2,500
Extended Maturity, Loan Two
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension term		4 years 6 months
Contributions to reserve account			2,000
Interest rate increase						8.50%
Increase to loan commitment			50,000
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in CECL reserve			(1,009)				10,117
CECL reserve	15,371	$ 15,371	15,371	15,371	$ 15,371	$ 15,371	16,380	16,380	16,380	6,263
Unfunded loan commitments	2,430,664	2,430,664	2,430,664	2,430,664	2,430,664	2,430,664	3,806,153	3,806,153	3,806,153
Unfunded Loan Commitment | Payment Deferral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	10,000	10,000	10,000	10,000	10,000	10,000
Unfunded Loan Commitment | Extended Maturity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	40,000	40,000	40,000	40,000	$ 40,000	40,000
One Loan Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan					1
Net book value	140,000	140,000	140,000	140,000	$ 140,000	140,000
Five Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
CECL reserve							189,800	189,800	$ 189,800
Number of loans | loan									5
Principal balance							929,100	929,100	$ 929,100
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan					54				60
Principal balance	9,253,609	9,253,609	9,253,609	9,253,609	$ 9,253,609	9,253,609	9,082,946	9,082,946	$ 9,082,946
Number of loan modifications | loan					4
Loans held	10,072,963	10,072,963	10,072,963	10,072,963	$ 10,072,963	10,072,963	10,023,495	10,023,495	$ 10,023,495
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan					23				30
Principal balance	4,161,525	4,161,525	4,161,525	4,161,525	$ 4,161,525	4,161,525	4,879,314	4,879,314	$ 4,879,314
Number of loan modifications | loan					1
Loans held	4,194,588	4,194,588	4,194,588	4,194,588	$ 4,194,588	4,194,588	4,908,583	4,908,583	$ 4,908,583
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan					73				80
Principal balance	5,876,128	5,876,128	5,876,128	5,876,128	$ 5,876,128	5,876,128	6,214,123	6,214,123	$ 6,214,123
Loans held	5,997,886	5,997,886	5,997,886	5,997,886	5,997,886	5,997,886	6,330,153	6,330,153	6,330,153
Impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in CECL reserve	95,100		227,892				134,904
CECL reserve	417,670	417,670	417,670	417,670	417,670	417,670	189,778	189,778	189,778	54,874
Interest income			0
Principal balance	1,877,279	1,877,279	1,877,279	1,877,279	1,877,279	1,877,279	929,111	929,111	929,111
Impaired loans | Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in CECL reserve			0				0
CECL reserve	$ 0	0	0	0	0	0	0	0	0	$ 0
Impaired loans | Three Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	3
Interest income	$ 5,900
Impaired loans | Thirteen Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
CECL reserve	417,700	417,700	417,700	417,700	$ 417,700	417,700
Number of loans | loan					13
Net book value	1,900,000	1,900,000	1,900,000	1,900,000	$ 1,900,000	1,900,000
Joint Venture | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held	$ 612,900	$ 612,900	$ 612,900	$ 612,900	$ 612,900	$ 612,900	$ 795,600	$ 795,600	$ 795,600