Loans Receivable, Net - Property Type and Geographic Distribution of Properties Securing Loans in Portfolio (Detail) $ in Thousands	Dec. 31, 2022 USD ($) SecurityLoan	Dec. 31, 2021 USD ($) SecurityLoan	Dec. 31, 2020 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	203	188
Net Book Value	$ 25,017,880	$ 22,003,017	$ 16,572,715
CECL reserve	(326,137)	(124,679)	$ (173,549)
Loans receivable, net	24,691,743	21,878,338
Total Loan Exposure	$ 26,810,281	$ 23,669,111
Percentage of Portfolio	100.00%	100.00%
Total loan exposure including senior interests	$ 1,600,000	$ 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	160	156
Net Book Value	$ 16,699,006	$ 15,357,571
Total Loan Exposure	$ 18,431,661	$ 16,706,378
Percentage of Portfolio	69.00%	71.00%
Sunbelt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	75	71
Net Book Value	$ 6,538,034	$ 5,907,230
Total Loan Exposure	$ 6,802,928	$ 6,206,216
Percentage of Portfolio	26.00%	26.00%
Northeast
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	36	37
Net Book Value	$ 5,339,874	$ 4,615,076
Total Loan Exposure	$ 5,666,968	$ 4,934,295
Percentage of Portfolio	21.00%	21.00%
West
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	33	33
Net Book Value	$ 3,515,517	$ 3,520,942
Total Loan Exposure	$ 4,547,946	$ 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
Net Book Value	$ 987,718	$ 1,063,202
Total Loan Exposure	$ 1,091,882	$ 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
Net Book Value	$ 317,863	$ 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	43	32
Net Book Value	$ 8,318,874	$ 6,645,446
Total Loan Exposure	$ 8,378,620	$ 6,962,733
Percentage of Portfolio	31.00%	29.00%
United Kingdom
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	23	17
Net Book Value	$ 3,362,629	$ 2,342,146
Total Loan Exposure	$ 3,393,126	$ 2,598,033
Percentage of Portfolio	13.00%	11.00%
Australia
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	5	4
Net Book Value	$ 1,405,601	$ 504,668
Total Loan Exposure	$ 1,417,318	$ 509,885
Percentage of Portfolio	5.00%	2.00%
Spain
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	4	4
Net Book Value	$ 1,237,446	$ 1,374,364
Total Loan Exposure	$ 1,241,808	$ 1,380,763
Percentage of Portfolio	5.00%	6.00%
Ireland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	3	1
Net Book Value	$ 1,192,220	$ 1,210,375
Total Loan Exposure	$ 1,199,406	$ 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
Net Book Value	$ 473,374	$ 546,319
Total Loan Exposure	$ 476,673	$ 551,149
Percentage of Portfolio	2.00%	2.00%
Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	1	2
Net Book Value	$ 49,409	$ 68,558
Total Loan Exposure	$ 49,432	$ 68,478
Percentage of Portfolio	0.00%	0.00%
Other Europe
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	6	3
Net Book Value	$ 598,195	$ 599,016
Total Loan Exposure	$ 600,857	$ 637,561
Percentage of Portfolio	2.00%	3.00%
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	64	65
Net Book Value	$ 9,441,622	$ 9,473,039
Total Loan Exposure	$ 10,593,584	$ 10,425,026
Percentage of Portfolio	40.00%	44.00%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	80	75
Net Book Value	$ 6,214,123	$ 5,721,260
Total Loan Exposure	$ 6,330,153	$ 5,771,517
Percentage of Portfolio	24.00%	24.00%
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	30	25
Net Book Value	$ 4,879,314	$ 3,427,245
Total Loan Exposure	$ 4,908,583	$ 3,540,391
Percentage of Portfolio	18.00%	15.00%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	12	6
Net Book Value	$ 2,140,636	$ 1,102,452
Total Loan Exposure	$ 2,236,716	$ 1,185,606
Percentage of Portfolio	8.00%	5.00%
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	9	8
Net Book Value	$ 1,098,315	$ 871,241
Total Loan Exposure	$ 1,141,932	$ 909,970
Percentage of Portfolio	4.00%	4.00%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	8	9
Net Book Value	$ 1,243,870	$ 1,407,780
Total Loan Exposure	$ 1,599,313	$ 1,836,601
Percentage of Portfolio	6.00%	8.00%