Loans Receivable, Net - Additional Information (Detail) $ in Thousands	3 Months Ended						12 Months Ended
	Mar. 31, 2025 USD ($)	Mar. 31, 2025 USD ($)	Mar. 31, 2025 USD ($) loan	Mar. 31, 2025 USD ($) security_loan	Mar. 31, 2025 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)	Dec. 31, 2024 USD ($) loan	Dec. 31, 2024 USD ($) security_loan	Dec. 31, 2023 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Weighted-average risk rating	3.0	3.0	3.0	3.0	3.0		3.0	3.0	3.0
Increase in net CECL reserve		$ 32,900
Increase in CECL reserves		49,429				$ 235,447
Amount charged off		41,824				61,013	$ 384,603
CECL reserve	$ 741,541	741,541	$ 741,541	$ 741,541	$ 741,541	751,370	733,936	$ 733,936	$ 733,936	$ 576,936
Number of loans			138	138				130	130
Interest and related income		332,057				486,122
Principal balance	19,049,712	19,049,712	$ 19,049,712	$ 19,049,712	19,049,712		19,047,518	$ 19,047,518	$ 19,047,518
Net book value	18,308,171	18,308,171	$ 18,308,171	18,308,171	18,308,171		18,313,582	18,313,582	18,313,582
Number of loan modifications | loan			6
Real estate owned, net	619,796	619,796	$ 619,796	619,796	619,796		588,185	588,185	588,185
Joint Venture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan exposure	43,300	43,300	43,300	43,300	43,300
Real estate owned, net	32,300	32,300	$ 32,300	32,300	32,300		32,400	$ 32,400	32,400
5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			13					13
Principal balance	1,521,766	1,521,766	$ 1,521,766	1,521,766	1,521,766		1,827,561	$ 1,827,561	1,827,561
4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			20					20
Principal balance	2,912,484	2,912,484	$ 2,912,484	2,912,484	2,912,484		2,707,104	$ 2,707,104	2,707,104
3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			75					65
Principal balance	$ 10,728,778	10,728,778	$ 10,728,778	10,728,778	$ 10,728,778		9,246,692	$ 9,246,692	9,246,692
Payment Deferral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan			1
Extension term	14 months
Aggregate amortized cost basis of loans		108,700
Percentage to aggregate loans receivable portfolio					0.60%
Extended Maturity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan			5
Aggregate amortized cost basis of loans		837,300
Percentage to aggregate loans receivable portfolio					4.40%
Extended Maturity | 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan			5
Extended Maturity | 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan			1
Extended Maturity, Loan One
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension term	2 years
Increase to loan commitment		34,500
Fixed coupon rate					15.00%
Floating rate					2.50%
Extended Maturity, Loan Two
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension term	5 years
Proceeds from repayment of loan		6,000
Extended Maturity, Loan Three
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension term	4 years 9 months 18 days
Increase (decrease) in rate					(0.10%)
Extended Maturity, Loan Four
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension term	3 years 9 months 18 days
Proceeds from repayment of loan		1,700
Extended Maturity, Loan Five
Accounts, Notes, Loans and Financing Receivable [Line Items]
Extension term	1 year
Increase (decrease) in rate					(2.43%)
Proceeds from repayment of loan		25,000
Extended Maturity, Senior Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan			4
Extended Maturity, Senior Loans | 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan			3
Extended Maturity, Senior Loans | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan			1
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			41					41
Principal balance	$ 5,925,523	5,925,523	$ 5,925,523	5,925,523	$ 5,925,523		7,386,333	$ 7,386,333	7,386,333
Number of loan modifications | loan			5
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			17					16
Principal balance	2,857,777	2,857,777	$ 2,857,777	2,857,777	2,857,777		2,768,374	$ 2,768,374	2,768,374
Mixed Use Asset
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan modifications | loan			1
One Loan Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			1
Net book value	195,000	195,000	$ 195,000	195,000	195,000
One Loan Past Due | Junior Loan Participation
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net book value	50,000	50,000	$ 50,000	50,000	50,000
13 Loans | Impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			13
Cash proceeds		18,900
Impaired loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase in CECL reserves		16,552				245,942
Amount charged off		41,824				61,013
CECL reserve	555,379	555,379	$ 555,379	555,379	555,379	$ 602,599	580,651	580,651	580,651	$ 417,670
Number of new loans impaired | loan			1
Number of loans | loan			1
Interest and related income		2,800
Principal balance	1,521,766	1,521,766	$ 1,521,766	1,521,766	1,521,766		1,827,561	1,827,561	1,827,561
Impaired loans | 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal balance	1,521,766	1,521,766	1,521,766	1,521,766	1,521,766		1,827,561	1,827,561	1,827,561
Impaired loans | 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal balance	0	0	0	0	0		0	0	0
Impaired loans | 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal balance	0	0	$ 0	0	0		$ 0	$ 0	$ 0
Unfunded Loan Commitment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan			57
Unfunded Loan Commitment | Payment Deferral
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	23,900	23,900	$ 23,900	23,900	23,900
Unfunded Loan Commitment | Extended Maturity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded loan commitments	$ 53,800	$ 53,800	$ 53,800	$ 53,800	$ 53,800