Related-Party Transactions - Summary of related-party transactions (Details) - AAMC - Affiliated entity - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Base management fees
Related Party Transaction [Line Items]
Related party expenses	$ 3,584	$ 3,556	$ 7,168	$ 7,102
Conversion fees
Related Party Transaction [Line Items]
Related party expenses	0	0	0	29
Expense reimbursements
Related Party Transaction [Line Items]
Related party expenses	$ 713	$ 342	$ 1,081	$ 670