Loans Receivable, Net - Property Type and Geographic Distribution of Properties Securing Loans in Portfolio (Detail) $ in Thousands	6 Months Ended			12 Months Ended
	Jun. 30, 2025 USD ($) loan	Jun. 30, 2025 USD ($) security_loan	Jun. 30, 2025 USD ($)	Dec. 31, 2024 USD ($) loan	Dec. 31, 2024 USD ($) security_loan	Dec. 31, 2024 USD ($)	Mar. 31, 2025 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans	144	144		130	130
Net book value	$ 19,706,105	$ 19,706,105	$ 19,706,105	$ 19,047,518	$ 19,047,518	$ 19,047,518
CECL reserve	(740,851)	(740,851)	(740,851)	(733,936)	(733,936)	(733,936)	$ (741,541)	$ (893,938)	$ (751,370)	$ (576,936)
Loans receivable, net	18,965,254	18,965,254	18,965,254	18,313,582	18,313,582	18,313,582
Net Loan Exposure	18,444,416	18,444,416	18,444,416	17,034,303	17,034,303	17,034,303
Cost-recovery proceeds	109,200	109,200	109,200	106,700	106,700	106,700
Loan participations sold	50,000	50,000	50,000	100,064	100,064	100,064
Asset-specific debt, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal balance	529,867	529,867	529,867	1,228,110	1,228,110	1,228,110
Long-term debt	528,224	528,224	528,224	1,224,841	1,224,841	1,224,841
Junior Loan Participation
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan participations sold	$ 50,000	50,000	$ 50,000	$ 100,064	100,064	$ 100,064
Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			100.00%			100.00%
Subtotal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	108			100
Net book value	$ 11,207,230	11,207,230	$ 11,207,230	$ 12,430,396	12,430,396	$ 12,430,396
Net Loan Exposure	$ 10,177,896	10,177,896	$ 10,177,896	$ 10,537,164	10,537,164	$ 10,537,164
Subtotal | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			55.00%			62.00%
Sunbelt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	49			44
Net book value	$ 5,008,396	5,008,396	$ 5,008,396	$ 4,520,632	4,520,632	$ 4,520,632
Net Loan Exposure	$ 4,485,034	4,485,034	$ 4,485,034	$ 4,084,242	4,084,242	$ 4,084,242
Sunbelt | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			24.00%			24.00%
Northeast
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	23			21
Net book value	$ 2,900,363	2,900,363	$ 2,900,363	$ 4,614,582	4,614,582	$ 4,614,582
Net Loan Exposure	$ 2,630,050	2,630,050	$ 2,630,050	$ 3,452,961	3,452,961	$ 3,452,961
Northeast | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			14.00%			20.00%
West
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	23			21
Net book value	$ 1,953,102	1,953,102	$ 1,953,102	$ 1,865,382	1,865,382	$ 1,865,382
Net Loan Exposure	$ 1,861,649	1,861,649	$ 1,861,649	$ 1,746,309	1,746,309	$ 1,746,309
West | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			10.00%			10.00%
Midwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	9			10
Net book value	$ 866,624	866,624	$ 866,624	$ 997,156	997,156	$ 997,156
Net Loan Exposure	$ 723,593	723,593	$ 723,593	$ 820,858	820,858	$ 820,858
Midwest | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			4.00%			5.00%
Northwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	4			4
Net book value	$ 478,745	478,745	$ 478,745	$ 432,644	432,644	$ 432,644
Net Loan Exposure	$ 477,570	477,570	$ 477,570	$ 432,794	432,794	$ 432,794
Northwest | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			3.00%			3.00%
Subtotal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	36			30
Net book value	$ 8,498,875	8,498,875	$ 8,498,875	$ 6,617,122	6,617,122	$ 6,617,122
Net Loan Exposure	$ 8,266,520	8,266,520	$ 8,266,520	$ 6,497,139	6,497,139	$ 6,497,139
Subtotal | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			45.00%			38.00%
United Kingdom
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	18			16
Net book value	$ 3,658,916	3,658,916	$ 3,658,916	$ 2,916,145	2,916,145	$ 2,916,145
Net Loan Exposure	$ 3,642,741	3,642,741	$ 3,642,741	$ 2,839,096	2,839,096	$ 2,839,096
United Kingdom | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			20.00%			17.00%
Ireland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	3			3
Net book value	$ 1,232,664	1,232,664	$ 1,232,664	$ 1,050,276	1,050,276	$ 1,050,276
Net Loan Exposure	$ 1,228,094	1,228,094	$ 1,228,094	$ 1,048,329	1,048,329	$ 1,048,329
Ireland | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			7.00%			6.00%
Australia
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	5			3
Net book value	$ 1,064,406	1,064,406	$ 1,064,406	$ 920,182	920,182	$ 920,182
Net Loan Exposure	$ 1,072,552	1,072,552	$ 1,072,552	$ 923,507	923,507	$ 923,507
Australia | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			6.00%			5.00%
Spain
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	2			3
Net book value	$ 747,836	747,836	$ 747,836	$ 785,368	785,368	$ 785,368
Net Loan Exposure	$ 699,814	699,814	$ 699,814	$ 744,287	744,287	$ 744,287
Spain | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			4.00%			4.00%
Sweden
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	1			1
Net book value	$ 502,790	502,790	$ 502,790	$ 429,084	429,084	$ 429,084
Net Loan Exposure	$ 502,836	502,836	$ 502,836	$ 429,724	429,724	$ 429,724
Sweden | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			3.00%			2.00%
Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	1
Net book value	$ 459,289	459,289	$ 459,289
Net Loan Exposure	$ 291,680	291,680	$ 291,680
Canada | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			2.00%
Other Europe
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	5			3
Net book value	$ 772,115	772,115	$ 772,115	$ 455,417	455,417	$ 455,417
Net Loan Exposure	$ 767,881	767,881	$ 767,881	$ 451,245	451,245	$ 451,245
Other Europe | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			3.00%			4.00%
Other International
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	1			1
Net book value	$ 60,859	60,859	$ 60,859	$ 60,650	60,650	$ 60,650
Net Loan Exposure	$ 60,922	60,922	$ 60,922	$ 60,951	60,951	$ 60,951
Other International | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			0.00%			0.00%
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	44			41
Net book value	$ 5,855,637	5,855,637	$ 5,855,637	$ 7,386,333	7,386,333	$ 7,386,333
Net Loan Exposure	$ 5,195,591	5,195,591	$ 5,195,591	$ 5,729,418	5,729,418	$ 5,729,418
Office | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			28.00%			33.00%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	52			50
Net book value	$ 5,139,630	5,139,630	$ 5,139,630	$ 5,091,767	5,091,767	$ 5,091,767
Net Loan Exposure	$ 4,958,946	4,958,946	$ 4,958,946	$ 4,934,364	4,934,364	$ 4,934,364
Multifamily | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			27.00%			29.00%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	17			11
Net book value	$ 3,425,450	3,425,450	$ 3,425,450	$ 2,030,627	2,030,627	$ 2,030,627
Net Loan Exposure	$ 3,392,611	3,392,611	$ 3,392,611	$ 2,000,831	2,000,831	$ 2,000,831
Industrial | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			18.00%			12.00%
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	17			16
Net book value	$ 2,842,904	2,842,904	$ 2,842,904	$ 2,768,374	2,768,374	$ 2,768,374
Net Loan Exposure	$ 2,731,203	2,731,203	$ 2,731,203	$ 2,663,349	2,663,349	$ 2,663,349
Hospitality | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			15.00%			16.00%
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	7			5
Net book value	$ 698,410	698,410	$ 698,410	$ 555,553	555,553	$ 555,553
Net Loan Exposure	$ 673,021	673,021	$ 673,021	$ 532,069	532,069	$ 532,069
Retail | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			4.00%			3.00%
Self-storage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	3
Net book value	$ 666,400	666,400	$ 666,400
Net Loan Exposure	$ 498,771	498,771	$ 498,771
Self-storage | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			3.00%
Life Sciences / Studio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	3			3
Net book value	$ 341,511	341,511	$ 341,511	$ 342,817	342,817	$ 342,817
Net Loan Exposure	$ 297,484	297,484	$ 297,484	$ 337,687	337,687	$ 337,687
Life Sciences / Studio | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			1.00%			2.00%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of Loans | loan	1			4
Net book value	$ 736,163	736,163	$ 736,163	$ 872,047	872,047	$ 872,047
Net Loan Exposure	$ 696,789	$ 696,789	$ 696,789	$ 836,585	$ 836,585	$ 836,585
Other | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			4.00%			5.00%