Loans Receivable, Net - Property Type and Geographic Distribution of Properties Securing Loans in Portfolio (Detail) $ in Thousands	Jun. 30, 2022 USD ($) SecurityLoan	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) SecurityLoan	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	205		188
Principal balance	$ 24,831,546		$ 22,003,017
CECL reserve	(133,024)	$ (122,221)	(124,679)	$ (128,945)	$ (172,100)	$ (173,549)
Loans receivable, net	24,698,522		21,878,338
Total Loan Exposure	$ 26,509,461		$ 23,669,111
Percentage of Portfolio	100.00%		100.00%
Total loan exposure including senior interests	$ 1,500,000		$ 1,500,000
2018 Single Asset Securitization
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loan amount, securitized			$ 379,300
Subtotal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	168		156
Principal balance	$ 16,667,887		$ 15,357,571
Total Loan Exposure	$ 18,283,864		$ 16,706,378
Percentage of Portfolio	69.00%		71.00%
Sunbelt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	78		71
Principal balance	$ 6,530,957		$ 5,907,230
Total Loan Exposure	$ 6,792,543		$ 6,206,216
Percentage of Portfolio	26.00%		26.00%
Northeast
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	40		37
Principal balance	$ 5,341,968		$ 4,615,076
Total Loan Exposure	$ 5,667,952		$ 4,934,295
Percentage of Portfolio	21.00%		21.00%
West
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	34		33
Principal balance	$ 3,476,401		$ 3,520,942
Total Loan Exposure	$ 4,394,168		$ 4,199,208
Percentage of Portfolio	17.00%		18.00%
Midwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	10		10
Principal balance	$ 1,001,165		$ 1,063,202
Total Loan Exposure	$ 1,107,264		$ 1,113,959
Percentage of Portfolio	4.00%		5.00%
Northwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	6		5
Principal balance	$ 317,396		$ 251,121
Total Loan Exposure	$ 321,937		$ 252,700
Percentage of Portfolio	1.00%		1.00%
Subtotal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	37		32
Principal balance	$ 8,163,659		$ 6,645,446
Total Loan Exposure	$ 8,225,597		$ 6,962,733
Percentage of Portfolio	31.00%		29.00%
United Kingdom
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	20		17
Principal balance	$ 3,179,066		$ 2,342,146
Total Loan Exposure	$ 3,210,116		$ 2,598,033
Percentage of Portfolio	12.00%		11.00%
Australia
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	5		4
Principal balance	$ 1,451,073		$ 504,668
Total Loan Exposure	$ 1,463,974		$ 509,885
Percentage of Portfolio	6.00%		2.00%
Spain
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	4		4
Principal balance	$ 1,241,840		$ 1,374,364
Total Loan Exposure	$ 1,247,087		$ 1,380,763
Percentage of Portfolio	5.00%		6.00%
Ireland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	2		1
Principal balance	$ 1,103,546		$ 1,210,375
Total Loan Exposure	$ 1,109,382		$ 1,216,864
Percentage of Portfolio	4.00%		5.00%
Sweden
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	1		1
Principal balance	$ 482,377		$ 546,319
Total Loan Exposure	$ 486,202		$ 551,149
Percentage of Portfolio	2.00%		2.00%
Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	1		2
Principal balance	$ 49,071		$ 68,558
Total Loan Exposure	$ 49,160		$ 68,478
Percentage of Portfolio	0.00%		0.00%
Other Europe
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	4		3
Principal balance	$ 656,686		$ 599,016
Total Loan Exposure	$ 659,676		$ 637,561
Percentage of Portfolio	2.00%		3.00%
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	67		65
Principal balance	$ 9,735,435		$ 9,473,039
Total Loan Exposure	$ 10,771,841		$ 10,425,026
Percentage of Portfolio	41.00%		44.00%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	83		75
Principal balance	$ 6,392,372		$ 5,721,260
Total Loan Exposure	$ 6,500,608		$ 5,771,517
Percentage of Portfolio	25.00%		24.00%
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	29		25
Principal balance	$ 4,979,191		$ 3,427,245
Total Loan Exposure	$ 5,014,033		$ 3,540,391
Percentage of Portfolio	19.00%		15.00%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	8		6
Principal balance	$ 1,547,660		$ 1,102,452
Total Loan Exposure	$ 1,636,239		$ 1,185,606
Percentage of Portfolio	6.00%		5.00%
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	9		8
Principal balance	$ 1,105,177		$ 871,241
Total Loan Exposure	$ 1,145,756		$ 909,970
Percentage of Portfolio	4.00%		4.00%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	9		9
Principal balance	$ 1,071,711		$ 1,407,780
Total Loan Exposure	$ 1,440,984		$ 1,836,601
Percentage of Portfolio	5.00%		8.00%