Loans Receivable, Net - Property Type and Geographic Distribution of Properties Securing Loans in Portfolio (Detail) $ in Thousands	Mar. 31, 2023 USD ($) SecurityLoan	Dec. 31, 2022 USD ($) SecurityLoan	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	199	203
Net Book Value	$ 24,896,364	$ 25,017,880
CECL reserve	(336,591)	(326,137)	$ (122,221)	$ (124,679)
Loans receivable, net	24,559,773	24,691,743
Total Loan Exposure	26,742,669	26,810,281
Net Loan Exposure	$ 23,631,557	$ 23,659,183
Percentage of Portfolio	100.00%	100.00%
Total loan exposure including non-consolidated senior interests	$ 1,700,000	$ 1,600,000
Net loan exposure, asset-specific debt	822,900	950,300
Net loan exposure, loan participations sold	$ 229,500	$ 224,700
Subtotal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	158	160
Net Book Value	$ 16,532,974	$ 16,699,006
Total Loan Exposure	18,324,264	18,431,661
Net Loan Exposure	$ 15,541,094	$ 15,605,716
Percentage of Portfolio	66.00%	66.00%
Sunbelt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	75	75
Net Book Value	$ 6,292,774	$ 6,538,034
Total Loan Exposure	6,570,466	6,802,928
Net Loan Exposure	$ 6,184,786	$ 6,244,886
Percentage of Portfolio	26.00%	27.00%
Northeast
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	35	36
Net Book Value	$ 5,437,995	$ 5,339,874
Total Loan Exposure	5,760,805	5,666,968
Net Loan Exposure	$ 4,588,703	$ 4,570,180
Percentage of Portfolio	20.00%	19.00%
West
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	32	33
Net Book Value	$ 3,483,559	$ 3,515,517
Total Loan Exposure	4,566,903	4,547,946
Net Loan Exposure	$ 3,451,543	$ 3,486,343
Percentage of Portfolio	15.00%	15.00%
Midwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	10	10
Net Book Value	$ 987,885	$ 987,718
Total Loan Exposure	1,091,506	1,091,882
Net Loan Exposure	$ 983,430	$ 984,151
Percentage of Portfolio	4.00%	4.00%
Northwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	6	6
Net Book Value	$ 330,761	$ 317,863
Total Loan Exposure	334,584	321,937
Net Loan Exposure	$ 332,632	$ 320,156
Percentage of Portfolio	1.00%	1.00%
Subtotal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	41	43
Net Book Value	$ 8,363,390	$ 8,318,874
Total Loan Exposure	8,418,405	8,378,620
Net Loan Exposure	$ 8,090,463	$ 8,053,467
Percentage of Portfolio	34.00%	34.00%
United Kingdom
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	23	23
Net Book Value	$ 3,506,565	$ 3,362,629
Total Loan Exposure	3,535,306	3,393,126
Net Loan Exposure	$ 3,261,329	$ 3,123,925
Percentage of Portfolio	14.00%	13.00%
Australia
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	5	5
Net Book Value	$ 1,388,484	$ 1,405,601
Total Loan Exposure	1,399,171	1,417,318
Net Loan Exposure	$ 1,392,851	$ 1,408,565
Percentage of Portfolio	6.00%	6.00%
Ireland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	3	3
Net Book Value	$ 1,205,717	$ 1,192,220
Total Loan Exposure	1,212,182	1,199,406
Net Loan Exposure	$ 1,210,638	$ 1,197,892
Percentage of Portfolio	5.00%	5.00%
Spain
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	3	4
Net Book Value	$ 1,129,574	$ 1,237,446
Total Loan Exposure	1,133,120	1,241,808
Net Loan Exposure	$ 1,095,200	$ 1,204,218
Percentage of Portfolio	5.00%	5.00%
Sweden
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	1	1
Net Book Value	$ 474,690	$ 473,374
Total Loan Exposure	477,768	476,673
Net Loan Exposure	$ 477,465	$ 476,367
Percentage of Portfolio	2.00%	2.00%
Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	1	1
Net Book Value	$ 49,571	$ 49,409
Total Loan Exposure	49,571	49,432
Net Loan Exposure	$ 49,535	$ 49,398
Percentage of Portfolio	0.00%	0.00%
Other Europe
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	5	6
Net Book Value	$ 608,789	$ 598,195
Total Loan Exposure	611,287	600,857
Net Loan Exposure	$ 603,445	$ 593,102
Percentage of Portfolio	2.00%	3.00%
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	58	60
Net Book Value	$ 9,044,537	$ 9,082,946
Total Loan Exposure	9,993,785	10,023,495
Net Loan Exposure	$ 8,160,735	$ 8,099,334
Percentage of Portfolio	34.00%	34.00%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	80	80
Net Book Value	$ 6,309,898	$ 6,214,123
Total Loan Exposure	6,437,276	6,330,153
Net Loan Exposure	$ 6,276,458	$ 6,189,298
Percentage of Portfolio	27.00%	26.00%
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	29	30
Net Book Value	$ 4,781,063	$ 4,879,314
Total Loan Exposure	4,807,007	4,908,583
Net Loan Exposure	$ 4,462,406	$ 4,552,404
Percentage of Portfolio	19.00%	19.00%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	12	12
Net Book Value	$ 2,182,281	$ 2,140,636
Total Loan Exposure	2,277,667	2,236,716
Net Loan Exposure	$ 2,190,900	$ 2,150,501
Percentage of Portfolio	9.00%	9.00%
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	8	9
Net Book Value	$ 958,158	$ 1,098,315
Total Loan Exposure	1,003,736	1,141,932
Net Loan Exposure	$ 948,243	$ 1,090,238
Percentage of Portfolio	4.00%	5.00%
Life Sciences/Studio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	4	4
Net Book Value	$ 373,001	$ 358,676
Total Loan Exposure	620,980	570,089
Net Loan Exposure	$ 374,199	$ 359,830
Percentage of Portfolio	2.00%	2.00%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	8	8
Net Book Value	$ 1,247,426	$ 1,243,870
Total Loan Exposure	1,602,218	1,599,313
Net Loan Exposure	$ 1,218,616	$ 1,217,578
Percentage of Portfolio	5.00%	5.00%