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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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Loans Receivable, Net - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) SecurityLoan loan	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) SecurityLoan	Dec. 31, 2021 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average risk rating	2.9		2.9
Increase in CECL reserve	$ 10,454	$ (2,458)
CECL reserve	$ 336,591	122,221	$ 326,137	$ 124,679
Number of loans \| SecurityLoan	199		203
Net book value	$ 24,559,773		$ 24,691,743
Cash proceeds	18,300
Loans held	$ 26,742,669		$ 26,810,281
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans \| SecurityLoan	80		80
Loans held	$ 6,437,276		$ 6,330,153
Impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in CECL reserve	7,480	0
CECL reserve	197,258	$ 54,874	189,778	$ 54,874
Interest income	0
Impaired loans \| One Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in CECL reserve	$ 7,500
Number of loans \| loan	1
Interest income	$ 1,800
Impaired loans \| Six Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
CECL reserve	$ 197,300
Number of loans \| loan	6
Net book value	$ 997,700
Joint Venture \| Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held	$ 797,700		$ 795,600