Loans Receivable, Net - Principal Balance and Net Book Value of Loans Receivable Based on Internal Risk Ratings (Detail) $ in Thousands	Dec. 31, 2021 USD ($) SecurityLoan	Dec. 31, 2020 USD ($) SecurityLoan	Dec. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	188	120
Principal balance	$ 22,003,017	$ 16,572,715	$ 16,164,801
Financing Receivable, Allowance for Credit Loss, Excluding Accrued Interest	(124,679)	(173,549)	$ 0
Loans receivable, net	21,878,338	16,399,166
Total Loan Exposure	$ 23,669,111	$ 17,454,621
1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	8	8
Principal balance	$ 642,776	$ 777,163
Total Loan Exposure	$ 645,854	$ 778,283
2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	28	17
Principal balance	$ 5,200,533	$ 2,513,848
Total Loan Exposure	$ 5,515,250	$ 2,528,835
3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	141	79
Principal balance	$ 13,604,027	$ 9,911,914
Total Loan Exposure	$ 14,944,045	$ 10,763,496
4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	10	14
Principal balance	$ 2,270,872	$ 3,032,593
Total Loan Exposure	$ 2,277,653	$ 3,045,309
Risk Rating 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | SecurityLoan	1	2
Principal balance	$ 284,809	$ 337,197
Total Loan Exposure	$ 286,309	$ 338,698