Investments in Real Estate Debt - Summary of Collateral Type of Properties Securing Investments in Real Estate Debt (Detail) $ in Thousands	Jun. 30, 2020 USD ($) Position	Dec. 31, 2019 USD ($) Position
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	217	203
Cost Basis	$ 5,168,122	$ 4,493,288
Fair Value	$ 4,649,372	$ 4,523,260
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	76	75
Cost Basis	$ 2,201,498	$ 2,252,556
Fair Value	$ 1,872,878	$ 2,259,102
Percentage Based on Fair Value	41.00%	50.00%
Multifamily [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	66	61
Cost Basis	$ 983,314	$ 596,184
Fair Value	$ 983,030	$ 613,470
Percentage Based on Fair Value	21.00%	14.00%
Office [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	38	37
Cost Basis	$ 779,106	$ 793,782
Fair Value	$ 701,185	$ 794,881
Percentage Based on Fair Value	15.00%	18.00%
Industrial [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	18	14
Cost Basis	$ 636,938	$ 375,975
Fair Value	$ 597,508	$ 378,147
Percentage Based on Fair Value	13.00%	8.00%
Diversified [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	13	10
Cost Basis	$ 311,689	$ 219,215
Fair Value	$ 284,412	$ 219,798
Percentage Based on Fair Value	6.00%	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	$ 194,729	$ 240,558
Percentage Based on Fair Value	4.00%	5.00%
Retail [Member]
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Number of Positions | Position	1	1
Cost Basis	$ 17,375	$ 17,374
Fair Value	$ 15,630	$ 17,304