Summary of Significant Accounting Policies - Summary of Assets Measured at Fair Value on Recurring Basis Using Level 3 (Detail) - Recurring [Member] - Level 3 [Member] $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Balance	$ 134,076
Accretion included in interest income	260
Unrealized gain (loss) included in income (loss) from investments in real estate debt	(15,192)
Balance	$ 119,144