Loans Receivable, Net - Overall Statistics for Loans Receivable Portfolio (Detail) $ in Thousands	3 Months Ended				12 Months Ended
	Mar. 31, 2025 USD ($)	Mar. 31, 2025 USD ($) loan	Mar. 31, 2025 USD ($) security_loan	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2024 USD ($) loan	Dec. 31, 2024 USD ($) security_loan	Dec. 31, 2024 USD ($)	Dec. 31, 2023	Mar. 31, 2024 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans		138	138			130	130
Principal balance	$ 19,217,768	$ 19,217,768	$ 19,217,768	$ 19,217,768	$ 19,203,126	$ 19,203,126	$ 19,203,126	$ 19,203,126
Net book value	18,308,171	18,308,171	18,308,171	18,308,171	18,313,582	18,313,582	18,313,582	18,313,582
Unfunded loan commitments	$ 10,487	$ 10,487	$ 10,487	$ 10,487	$ 10,412	$ 10,412	$ 10,412	$ 10,412		$ 12,600
Weighted-average cash coupon (percentage)	3.39%	3.39%	3.39%	3.39%	3.46%	3.46%	3.46%	3.46%
Weighted-average all-in yield (percentage)				3.70%				3.78%
Weighted-average maximum maturity (years)	2 years 3 months 18 days				2 years 1 month 6 days
Debt instrument, variable interest rate, type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR)				Secured Overnight Financing Rate (SOFR)				Secured Overnight Financing Rate (SOFR)
Percent of loans subject to prepayment restrictions	17.00%	17.00%	17.00%	17.00%	10.00%	10.00%	10.00%	10.00%
Percent of loans not subject to prepayment restrictions	83.00%	83.00%	83.00%	83.00%	90.00%	90.00%	90.00%	90.00%
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan		57
Unfunded loan commitments	$ 1,033,229	$ 1,033,229	$ 1,033,229	$ 1,033,229	$ 1,263,068	$ 1,263,068	$ 1,263,068	$ 1,263,068