Investments in Real Estate Debt - Additional Information (Detail) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($) Security	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($) Security	Dec. 31, 2019 USD ($)
Marketable Securities [Line Items]
Investments in real estate debt, cost basis	$ 5,168,122		$ 5,168,122		$ 4,493,288
Unrealized gain (loss) from investments in real estate debt	466,400	$ 20,800	(548,700)	$ 51,800
Realized gain (loss) from investments in real estate debt	(5,000)		(4,700)
Number of real estate related securities sold | Security		2		2
Commercial Mortgage Backed Securities Collateralized by Pools of Commercial Real Estate Debt [Member]
Marketable Securities [Line Items]
Investments in real estate debt, cost basis	166,700		166,700		$ 186,800
Interest income recorded	$ 2,500	$ 1,700	$ 5,100	$ 3,300