Loans Receivable, Net - Additional Information (Detail) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2023 USD ($) loan security_loan	Mar. 31, 2023 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Jun. 30, 2023 USD ($) loan security_loan	Dec. 31, 2022 USD ($) security_loan	Dec. 31, 2021 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average risk rating	2.9				2.9	2.9
Increase in CECL reserve	$ 27,284	$ 10,454	$ 10,803	$ (2,458)
CECL reserve	$ 363,875	336,591	133,024	122,221	$ 363,875	$ 326,137	$ 124,679
Number of loans | security_loan	191				191	203
Net book value	$ 24,118,874				$ 24,118,874	$ 24,691,743
Cash proceeds	$ 12,300
Number of loan modifications | loan	3
Loans held	$ 25,755,473				25,755,473	26,810,281
Payment Deferral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan	2
Extension term	6 months
Contributions to reserve account	$ 2,000
Interest rate increase	5.11%
Exit fee percentage	4.00%
Aggregate amortized cost basis of loans	$ 286,700
Percentage to aggregate loans receivable portfolio	1.20%
Extended Maturity and Interest Rate Reduction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Contributions to reserve account	$ 4,900
Aggregate amortized cost basis of loans	$ 229,900
Percentage to aggregate loans receivable portfolio	0.90%
Repayment due by borrower at maturity period	$ 2,500
Extended Maturity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension term	19 months
Contractual Interest Rate Reduction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Interest rate reduction	2.74%
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in CECL reserve	$ 523	(631)	2,180	(9)
CECL reserve	16,272	15,749	8,434	6,254	16,272	16,380	6,263
Unfunded loan commitments	3,009,727				3,009,727	$ 3,806,153
Unfunded Loan Commitment | Payment Deferral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	10,000				10,000
Unfunded Loan Commitment | Extended Maturity and Interest Rate Reduction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	$ 0				$ 0
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | security_loan	78				78	80
Loans held	$ 6,215,656				$ 6,215,656	$ 6,330,153
Impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in CECL reserve	17,143	7,480	0	0
CECL reserve	214,401	197,258	54,874	54,874	214,401	189,778	54,874
Interest income					0
Impaired loans | Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in CECL reserve	0	0	0	0
CECL reserve	$ 0	$ 0	$ 0	$ 0	$ 0	0	$ 0
Impaired loans | One Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	1				1
Interest income	$ 2,100
Impaired loans | Seven Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
CECL reserve	$ 214,400				$ 214,400
Number of loans | loan	7				7
Net book value	$ 1,100,000				$ 1,100,000
Joint Venture | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held	$ 798,600				$ 798,600	$ 795,600