Loans Receivable, Net - Principal Balance and Net Book Value of Loans Receivable Based on Internal Risk Ratings (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
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
1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	12		8
Principal balance	$ 836,222		$ 642,776
Total Loan Exposure	$ 868,722		$ 645,854
2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	39		28
Principal balance	$ 5,856,051		$ 5,200,533
Total Loan Exposure	$ 6,178,959		$ 5,515,250
3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	143		141
Principal balance	$ 15,773,096		$ 13,604,027
Total Loan Exposure	$ 17,089,166		$ 14,944,045
4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	10		10
Principal balance	$ 2,081,368		$ 2,270,872
Total Loan Exposure	$ 2,086,305		$ 2,277,653
5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	1		1
Principal balance	$ 284,809		$ 284,809
Total Loan Exposure	$ 286,309		$ 286,309