Loans Receivable, Net - Overall Statistics for Loans Receivable Portfolio (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2024 USD ($)	Dec. 31, 2024 USD ($) loan	Dec. 31, 2024 USD ($) security_loan	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) loan	Dec. 31, 2023 USD ($) security_loan	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans		130	130			178	178
Principal balance	$ 19,203,126	$ 19,203,126	$ 19,203,126	$ 19,203,126	$ 23,923,719	$ 23,923,719	$ 23,923,719	$ 23,923,719	$ 25,160,343
Net book value	18,313,582	18,313,582	18,313,582	18,313,582	23,210,076	23,210,076	23,210,076	23,210,076
Unfunded loan commitments	$ 10,412	$ 10,412	$ 10,412	$ 10,412	$ 15,371	$ 15,371	$ 15,371	$ 15,371
Weighted-average cash coupon (percentage)	3.46%	3.46%	3.46%	3.46%	3.37%	3.37%	3.37%	3.37%
Weighted-average all-in yield (percentage)				3.78%				3.71%
Weighted-average maximum maturity (years)	2 years 1 month 6 days				2 years 6 months
Debt instrument, variable interest rate, type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR)				Secured Overnight Financing Rate (SOFR)
Percentage of loans by principal balance, floating rate					99.00%	99.00%	99.00%	99.00%
Percentage of loans by principal balance, fixed rate					1.00%	1.00%	1.00%	1.00%
Percent of loans subject to prepayment restrictions	10.00%	10.00%	10.00%	10.00%	14.00%	14.00%	14.00%	14.00%
Percent of loans not subject to prepayment restrictions	90.00%	90.00%	90.00%	90.00%	86.00%	86.00%	86.00%	86.00%
Interest Rate Swaps
Accounts, Notes, Loans and Financing Receivable [Line Items]
Notional amount					$ 229,900	$ 229,900	$ 229,900	$ 229,900
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan		60
Unfunded loan commitments	$ 1,263,068	$ 1,263,068	$ 1,263,068	$ 1,263,068	$ 2,430,664	$ 2,430,664	$ 2,430,664	$ 2,430,664