Investments in Real Estate Debt - Summary of Collateral Type of Properties Securing Investments in Real Estate Debt (Detail) $ in Thousands	Mar. 31, 2021 USD ($) Position	Dec. 31, 2020 USD ($) Position
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	260	228
Cost Basis	$ 4,923,780	$ 4,723,514
Fair Value	$ 4,896,416	$ 4,566,306
Percentage Based on Fair Value	100.00%	100.00%
Hospitality [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	79	78
Cost Basis	$ 2,094,352	$ 2,046,529
Fair Value	$ 2,038,382	$ 1,904,256
Percentage Based on Fair Value	42.00%	42.00%
Multifamily [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	71	58
Cost Basis	$ 734,737	$ 748,086
Fair Value	$ 775,270	$ 797,840
Percentage Based on Fair Value	16.00%	17.00%
Office [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	40	36
Cost Basis	$ 732,790	$ 720,665
Fair Value	$ 709,461	$ 681,596
Percentage Based on Fair Value	15.00%	15.00%
Industrial [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	42	29
Cost Basis	$ 779,263	$ 612,884
Fair Value	$ 786,859	$ 610,504
Percentage Based on Fair Value	16.00%	13.00%
Diversified [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	19	18
Cost Basis	$ 215,687	$ 234,527
Fair Value	$ 217,756	$ 225,077
Percentage Based on Fair Value	4.00%	5.00%
Other [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	5	5
Cost Basis	$ 238,202	$ 238,202
Fair Value	$ 232,115	$ 213,654
Percentage Based on Fair Value	5.00%	5.00%
Net Lease [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	3	3
Cost Basis	$ 111,374	$ 105,246
Fair Value	$ 120,118	$ 117,219
Percentage Based on Fair Value	2.00%	3.00%
Retail [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	1	1
Cost Basis	$ 17,375	$ 17,375
Fair Value	$ 16,455	$ 16,160