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, 2024 USD ($) loan	Jun. 30, 2024 USD ($) security_loan	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($) loan	Dec. 31, 2023 USD ($) security_loan	Dec. 31, 2023 USD ($)	Mar. 31, 2024 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans	166	166		178	178
Net Book Value	$ 22,870,848	$ 22,870,848	$ 22,870,848	$ 23,787,012	$ 23,787,012	$ 23,787,012
CECL reserve	(893,938)	(893,938)	(893,938)	(576,936)	(576,936)	(576,936)	$ (751,370)	$ (363,875)	$ (336,591)	$ (326,137)
Loans receivable, net	21,976,910	21,976,910	21,976,910	23,210,076	23,210,076	23,210,076
Total Loan Exposure	23,635,509	23,635,509	23,635,509	24,971,028	24,971,028	24,971,028
Net Loan Exposure	20,814,030	20,814,030	20,814,030	21,951,988	21,951,988	21,951,988
Principal balance	23,010,660	23,010,660	23,010,660	23,923,719	23,923,719	23,923,719
Total loan exposure including non-consolidated senior interests	725,400	725,400	725,400	1,100,000	1,100,000	1,100,000
Loan participations sold	100,580	100,580	100,580	337,721	337,721	337,721
Cost-recovery proceeds	76,300	76,300	76,300	53,000	53,000	53,000
Asset-specific debt, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total obligation	1,120,760	1,120,760	1,120,760	1,000,210	1,000,210	1,000,210
Junior Loan Participation
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan participations sold	$ 100,580	100,580	$ 100,580	100,924	100,924	100,924
Senior Participations
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan participations sold				$ 236,797	236,797	$ 236,797
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	130			141
Net Book Value	$ 14,893,777	14,893,777	$ 14,893,777	$ 15,460,479	15,460,479	$ 15,460,479
Total Loan Exposure	15,678,048	15,678,048	15,678,048	16,652,620	16,652,620	16,652,620
Net Loan Exposure	$ 12,928,989	12,928,989	$ 12,928,989	$ 13,951,306	13,951,306	$ 13,951,306
Subtotal | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			62.00%			64.00%
Sunbelt
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	61			65
Net Book Value	$ 5,510,438	5,510,438	$ 5,510,438	$ 5,658,172	5,658,172	$ 5,658,172
Total Loan Exposure	5,615,694	5,615,694	5,615,694	5,786,395	5,786,395	5,786,395
Net Loan Exposure	$ 5,119,961	5,119,961	$ 5,119,961	$ 5,402,732	5,402,732	$ 5,402,732
Sunbelt | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			24.00%			25.00%
Northeast
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	25			30
Net Book Value	$ 5,111,794	5,111,794	$ 5,111,794	$ 5,386,940	5,386,940	$ 5,386,940
Total Loan Exposure	5,162,565	5,162,565	5,162,565	5,426,951	5,426,951	5,426,951
Net Loan Exposure	$ 3,908,921	3,908,921	$ 3,908,921	$ 4,340,660	4,340,660	$ 4,340,660
Northeast | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			19.00%			20.00%
West
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	29			31
Net Book Value	$ 2,895,255	2,895,255	$ 2,895,255	$ 3,088,644	3,088,644	$ 3,088,644
Total Loan Exposure	3,516,394	3,516,394	3,516,394	4,108,074	4,108,074	4,108,074
Net Loan Exposure	$ 2,683,597	2,683,597	$ 2,683,597	$ 2,910,559	2,910,559	$ 2,910,559
West | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			13.00%			13.00%
Midwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	9			9
Net Book Value	$ 943,073	943,073	$ 943,073	$ 944,132	944,132	$ 944,132
Total Loan Exposure	947,317	947,317	947,317	945,222	945,222	945,222
Net Loan Exposure	$ 783,171	783,171	$ 783,171	$ 913,973	913,973	$ 913,973
Midwest | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			4.00%			4.00%
Northwest
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	6			6
Net Book Value	$ 433,217	433,217	$ 433,217	$ 382,591	382,591	$ 382,591
Total Loan Exposure	436,078	436,078	436,078	385,978	385,978	385,978
Net Loan Exposure	$ 433,339	433,339	$ 433,339	$ 383,382	383,382	$ 383,382
Northwest | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			2.00%			2.00%
Subtotal
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	36			37
Net Book Value	$ 7,977,071	7,977,071	$ 7,977,071	$ 8,326,533	8,326,533	$ 8,326,533
Total Loan Exposure	7,957,461	7,957,461	7,957,461	8,318,408	8,318,408	8,318,408
Net Loan Exposure	$ 7,885,041	7,885,041	$ 7,885,041	$ 8,000,682	8,000,682	$ 8,000,682
Subtotal | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			38.00%			36.00%
United Kingdom
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	18			20
Net Book Value	$ 3,163,864	3,163,864	$ 3,163,864	$ 3,470,120	3,470,120	$ 3,470,120
Total Loan Exposure	3,128,584	3,128,584	3,128,584	3,439,678	3,439,678	3,439,678
Net Loan Exposure	$ 3,109,414	3,109,414	$ 3,109,414	$ 3,181,489	3,181,489	$ 3,181,489
United Kingdom | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			15.00%			14.00%
Australia
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	5			5
Net Book Value	$ 1,414,495	1,414,495	$ 1,414,495	$ 1,429,144	1,429,144	$ 1,429,144
Total Loan Exposure	1,421,417	1,421,417	1,421,417	1,437,870	1,437,870	1,437,870
Net Loan Exposure	$ 1,417,265	1,417,265	$ 1,417,265	$ 1,432,146	1,432,146	$ 1,432,146
Australia | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			7.00%			7.00%
Ireland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	3			3
Net Book Value	$ 1,186,407	1,186,407	$ 1,186,407	$ 1,191,068	1,191,068	$ 1,191,068
Total Loan Exposure	1,189,435	1,189,435	1,189,435	1,197,337	1,197,337	1,197,337
Net Loan Exposure	$ 1,181,231	1,181,231	$ 1,181,231	$ 1,188,554	1,188,554	$ 1,188,554
Ireland | 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	3			3
Net Book Value	$ 1,075,481	1,075,481	$ 1,075,481	$ 1,117,790	1,117,790	$ 1,117,790
Total Loan Exposure	1,077,083	1,077,083	1,077,083	1,120,375	1,120,375	1,120,375
Net Loan Exposure	$ 1,040,229	1,040,229	$ 1,040,229	$ 1,078,811	1,078,811	$ 1,078,811
Spain | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			5.00%			5.00%
Sweden
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	1			1
Net Book Value	$ 448,421	448,421	$ 448,421	$ 474,262	474,262	$ 474,262
Total Loan Exposure	450,288	450,288	450,288	476,718	476,718	476,718
Net Loan Exposure	$ 449,900	449,900	$ 449,900	$ 476,281	476,281	$ 476,281
Sweden | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			2.00%			2.00%
Other Europe
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	5			5
Net Book Value	$ 631,014	631,014	$ 631,014	$ 644,149	644,149	$ 644,149
Total Loan Exposure	632,654	632,654	632,654	646,430	646,430	646,430
Net Loan Exposure	$ 629,396	629,396	$ 629,396	$ 643,401	643,401	$ 643,401
Other Europe | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			3.00%			3.00%
Other International
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	1
Net Book Value	$ 57,389	57,389	$ 57,389
Total Loan Exposure	58,000	58,000	58,000
Net Loan Exposure	$ 57,606	57,606	$ 57,606
Other International | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			0.00%
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	51			54
Net Book Value	$ 9,047,507	9,047,507	$ 9,047,507	$ 9,253,609	9,253,609	$ 9,253,609
Total Loan Exposure	9,374,141	9,374,141	9,374,141	10,072,963	10,072,963	10,072,963
Net Loan Exposure	$ 7,348,500	7,348,500	$ 7,348,500	$ 7,956,472	7,956,472	$ 7,956,472
Office | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			36.00%			36.00%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	68			73
Net Book Value	$ 5,838,389	5,838,389	$ 5,838,389	$ 5,876,128	5,876,128	$ 5,876,128
Total Loan Exposure	6,006,124	6,006,124	6,006,124	5,997,886	5,997,886	5,997,886
Net Loan Exposure	$ 5,696,575	5,696,575	$ 5,696,575	$ 5,756,192	5,756,192	$ 5,756,192
Multifamily | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			27.00%			26.00%
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	20			23
Net Book Value	$ 3,786,040	3,786,040	$ 3,786,040	$ 4,161,525	4,161,525	$ 4,161,525
Total Loan Exposure	3,823,926	3,823,926	3,823,926	4,194,588	4,194,588	4,194,588
Net Loan Exposure	$ 3,654,726	3,654,726	$ 3,654,726	$ 3,804,091	3,804,091	$ 3,804,091
Hospitality | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			18.00%			17.00%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	12			12
Net Book Value	$ 2,183,312	2,183,312	$ 2,183,312	$ 2,189,808	2,189,808	$ 2,189,808
Total Loan Exposure	2,193,009	2,193,009	2,193,009	2,201,497	2,201,497	2,201,497
Net Loan Exposure	$ 2,159,637	2,159,637	$ 2,159,637	$ 2,190,914	2,190,914	$ 2,190,914
Industrial | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			10.00%			10.00%
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	6			6
Net Book Value	$ 713,181	713,181	$ 713,181	$ 814,241	814,241	$ 814,241
Total Loan Exposure	738,450	738,450	738,450	834,825	834,825	834,825
Net Loan Exposure	$ 684,155	684,155	$ 684,155	$ 785,573	785,573	$ 785,573
Retail | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			3.00%			4.00%
Life Sciences / Studio
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	4			4
Net Book Value	$ 392,678	392,678	$ 392,678	$ 385,098	385,098	$ 385,098
Total Loan Exposure	589,211	589,211	589,211	561,517	561,517	561,517
Net Loan Exposure	$ 391,463	391,463	$ 391,463	$ 384,219	384,219	$ 384,219
Life Sciences / Studio | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			2.00%			2.00%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans | loan	5			6
Net Book Value	$ 909,741	909,741	$ 909,741	$ 1,106,603	1,106,603	$ 1,106,603
Total Loan Exposure	910,648	910,648	910,648	1,107,752	1,107,752	1,107,752
Net Loan Exposure	$ 878,974	$ 878,974	$ 878,974	$ 1,074,527	$ 1,074,527	$ 1,074,527
Other | Loan Exposure Risk | Financing Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net Loan Exposure Percentage of Portfolio			4.00%			5.00%