Loans Receivable, Net - Property Type and Geographic Distribution of Properties Securing Loans in Portfolio (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) security_loan	Dec. 31, 2023 USD ($) loan	Dec. 31, 2022 USD ($) security_loan	Dec. 31, 2022 USD ($) loan	Dec. 31, 2021 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans		178	178	203	203
Net Book Value	$ 23,787,012	$ 23,787,012	$ 23,787,012	$ 25,017,880	$ 25,017,880	$ 22,003,017
CECL reserve	(576,936)	(576,936)	(576,936)	(326,137)	(326,137)	(124,679)
Loans receivable, net	23,210,076	23,210,076	23,210,076	24,691,743	24,691,743
Total Loan Exposure	24,971,028	24,971,028	24,971,028	26,810,281	26,810,281
Net Loan Exposure	$ 21,951,988	$ 21,951,988	$ 21,951,988	$ 23,659,183	$ 23,659,183
Percentage of portfolio	100.00%	100.00%	100.00%	100.00%	100.00%
Principal balance	$ 23,923,719	$ 23,923,719	$ 23,923,719	$ 25,160,343	$ 25,160,343	$ 22,156,437
Total loan exposure including non-consolidated senior interests	1,100,000	1,100,000	1,100,000	1,600,000	1,600,000
Loan participations sold	337,721	337,721	337,721	224,744	224,744
Net loan exposure, asset-specific debt	1,000,000	1,000,000	1,000,000	950,300	950,300
Cost-recovery proceeds	52,978
Junior Loan Participation
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan participations sold	100,924	100,924	100,924
Senior Participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan participations sold	236,797	236,797	$ 236,797	224,744	$ 224,744
Subtotal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			141		160
Net Book Value	15,460,479	15,460,479	$ 15,460,479	16,699,006	$ 16,699,006
Total Loan Exposure	16,652,620	16,652,620	16,652,620	18,431,661	18,431,661
Net Loan Exposure	$ 13,951,306	$ 13,951,306	$ 13,951,306	$ 15,605,716	$ 15,605,716
Percentage of portfolio	64.00%	64.00%	64.00%	66.00%	66.00%
Sunbelt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			65		75
Net Book Value	$ 5,658,172	$ 5,658,172	$ 5,658,172	$ 6,538,034	$ 6,538,034
Total Loan Exposure	5,786,395	5,786,395	5,786,395	6,802,928	6,802,928
Net Loan Exposure	$ 5,402,732	$ 5,402,732	$ 5,402,732	$ 6,244,886	$ 6,244,886
Percentage of portfolio	25.00%	25.00%	25.00%	27.00%	27.00%
Northeast
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			30		36
Net Book Value	$ 5,386,940	$ 5,386,940	$ 5,386,940	$ 5,339,874	$ 5,339,874
Total Loan Exposure	5,426,951	5,426,951	5,426,951	5,666,968	5,666,968
Net Loan Exposure	$ 4,340,660	$ 4,340,660	$ 4,340,660	$ 4,570,180	$ 4,570,180
Percentage of portfolio	20.00%	20.00%	20.00%	19.00%	19.00%
West
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			31		33
Net Book Value	$ 3,088,644	$ 3,088,644	$ 3,088,644	$ 3,515,517	$ 3,515,517
Total Loan Exposure	4,108,074	4,108,074	4,108,074	4,547,946	4,547,946
Net Loan Exposure	$ 2,910,559	$ 2,910,559	$ 2,910,559	$ 3,486,343	$ 3,486,343
Percentage of portfolio	13.00%	13.00%	13.00%	15.00%	15.00%
Midwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			9		10
Net Book Value	$ 944,132	$ 944,132	$ 944,132	$ 987,718	$ 987,718
Total Loan Exposure	945,222	945,222	945,222	1,091,882	1,091,882
Net Loan Exposure	$ 913,973	$ 913,973	$ 913,973	$ 984,151	$ 984,151
Percentage of portfolio	4.00%	4.00%	4.00%	4.00%	4.00%
Northwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			6		6
Net Book Value	$ 382,591	$ 382,591	$ 382,591	$ 317,863	$ 317,863
Total Loan Exposure	385,978	385,978	385,978	321,937	321,937
Net Loan Exposure	$ 383,382	$ 383,382	$ 383,382	$ 320,156	$ 320,156
Percentage of portfolio	2.00%	2.00%	2.00%	1.00%	1.00%
Subtotal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			37		43
Net Book Value	$ 8,326,533	$ 8,326,533	$ 8,326,533	$ 8,318,874	$ 8,318,874
Total Loan Exposure	8,318,408	8,318,408	8,318,408	8,378,620	8,378,620
Net Loan Exposure	$ 8,000,682	$ 8,000,682	$ 8,000,682	$ 8,053,467	$ 8,053,467
Percentage of portfolio	36.00%	36.00%	36.00%	34.00%	34.00%
United Kingdom
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			20		23
Net Book Value	$ 3,470,120	$ 3,470,120	$ 3,470,120	$ 3,362,629	$ 3,362,629
Total Loan Exposure	3,439,678	3,439,678	3,439,678	3,393,126	3,393,126
Net Loan Exposure	$ 3,181,489	$ 3,181,489	$ 3,181,489	$ 3,123,925	$ 3,123,925
Percentage of portfolio	14.00%	14.00%	14.00%	13.00%	13.00%
Australia
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			5		5
Net Book Value	$ 1,429,144	$ 1,429,144	$ 1,429,144	$ 1,405,601	$ 1,405,601
Total Loan Exposure	1,437,870	1,437,870	1,437,870	1,417,318	1,417,318
Net Loan Exposure	$ 1,432,146	$ 1,432,146	$ 1,432,146	$ 1,408,565	$ 1,408,565
Percentage of portfolio	7.00%	7.00%	7.00%	6.00%	6.00%
Ireland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			3		3
Net Book Value	$ 1,191,068	$ 1,191,068	$ 1,191,068	$ 1,192,220	$ 1,192,220
Total Loan Exposure	1,197,337	1,197,337	1,197,337	1,199,406	1,199,406
Net Loan Exposure	$ 1,188,554	$ 1,188,554	$ 1,188,554	$ 1,197,892	$ 1,197,892
Percentage of portfolio	5.00%	5.00%	5.00%	5.00%	5.00%
Spain
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			3		4
Net Book Value	$ 1,117,790	$ 1,117,790	$ 1,117,790	$ 1,237,446	$ 1,237,446
Total Loan Exposure	1,120,375	1,120,375	1,120,375	1,241,808	1,241,808
Net Loan Exposure	$ 1,078,811	$ 1,078,811	$ 1,078,811	$ 1,204,218	$ 1,204,218
Percentage of portfolio	5.00%	5.00%	5.00%	5.00%	5.00%
Sweden
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			1		1
Net Book Value	$ 474,262	$ 474,262	$ 474,262	$ 473,374	$ 473,374
Total Loan Exposure	476,718	476,718	476,718	476,673	476,673
Net Loan Exposure	$ 476,281	$ 476,281	$ 476,281	$ 476,367	$ 476,367
Percentage of portfolio	2.00%	2.00%	2.00%	2.00%	2.00%
Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan					1
Net Book Value				$ 49,409	$ 49,409
Total Loan Exposure				49,432	49,432
Net Loan Exposure				$ 49,398	$ 49,398
Percentage of portfolio				0.00%	0.00%
Other Europe
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			5		6
Net Book Value	$ 644,149	$ 644,149	$ 644,149	$ 598,195	$ 598,195
Total Loan Exposure	646,430	646,430	646,430	600,857	600,857
Net Loan Exposure	$ 643,401	$ 643,401	$ 643,401	$ 593,102	$ 593,102
Percentage of portfolio	3.00%	3.00%	3.00%	3.00%	3.00%
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			54		60
Net Book Value	$ 9,253,609	$ 9,253,609	$ 9,253,609	$ 9,082,946	$ 9,082,946
Total Loan Exposure	10,072,963	10,072,963	10,072,963	10,023,495	10,023,495
Net Loan Exposure	$ 7,956,472	$ 7,956,472	$ 7,956,472	$ 8,099,334	$ 8,099,334
Percentage of portfolio	36.00%	36.00%	36.00%	34.00%	34.00%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			73		80
Net Book Value	$ 5,876,128	$ 5,876,128	$ 5,876,128	$ 6,214,123	$ 6,214,123
Total Loan Exposure	5,997,886	5,997,886	5,997,886	6,330,153	6,330,153
Net Loan Exposure	$ 5,756,192	$ 5,756,192	$ 5,756,192	$ 6,189,298	$ 6,189,298
Percentage of portfolio	26.00%	26.00%	26.00%	26.00%	26.00%
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			23		30
Net Book Value	$ 4,161,525	$ 4,161,525	$ 4,161,525	$ 4,879,314	$ 4,879,314
Total Loan Exposure	4,194,588	4,194,588	4,194,588	4,908,583	4,908,583
Net Loan Exposure	$ 3,804,091	$ 3,804,091	$ 3,804,091	$ 4,552,404	$ 4,552,404
Percentage of portfolio	17.00%	17.00%	17.00%	19.00%	19.00%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			12		12
Net Book Value	$ 2,189,808	$ 2,189,808	$ 2,189,808	$ 2,140,636	$ 2,140,636
Total Loan Exposure	2,201,497	2,201,497	2,201,497	2,236,716	2,236,716
Net Loan Exposure	$ 2,190,914	$ 2,190,914	$ 2,190,914	$ 2,150,501	$ 2,150,501
Percentage of portfolio	10.00%	10.00%	10.00%	9.00%	9.00%
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			6		9
Net Book Value	$ 814,241	$ 814,241	$ 814,241	$ 1,098,315	$ 1,098,315
Total Loan Exposure	834,825	834,825	834,825	1,141,932	1,141,932
Net Loan Exposure	$ 785,573	$ 785,573	$ 785,573	$ 1,090,238	$ 1,090,238
Percentage of portfolio	4.00%	4.00%	4.00%	5.00%	5.00%
Life Sciences / Studio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			4		4
Net Book Value	$ 385,098	$ 385,098	$ 385,098	$ 358,676	$ 358,676
Total Loan Exposure	561,517	561,517	561,517	570,089	570,089
Net Loan Exposure	$ 384,219	$ 384,219	$ 384,219	$ 359,830	$ 359,830
Percentage of portfolio	2.00%	2.00%	2.00%	2.00%	2.00%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			6		8
Net Book Value	$ 1,106,603	$ 1,106,603	$ 1,106,603	$ 1,243,870	$ 1,243,870
Total Loan Exposure	1,107,752	1,107,752	1,107,752	1,599,313	1,599,313
Net Loan Exposure	$ 1,074,527	$ 1,074,527	$ 1,074,527	$ 1,217,578	$ 1,217,578
Percentage of portfolio	5.00%	5.00%	5.00%	5.00%	5.00%