Asset Acquisitions and Dispositions - Net gain (loss) on real estate and mortgage loans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Real Estate And Mortgage Loans On Real Estate Acquisitions And Disposals [Abstract]
Conversion of mortgage loans to REO, net	$ 0	$ 137	$ 0	$ 752
Change in fair value of mortgage loans, net	0	176	0	292
Net realized gain on mortgage loans	0	204	0	727
Net realized (loss) gain on sales of real estate	(163)	3,325	1,370	10,848
Net (loss) gain on real estate and mortgage loans	$ (163)	$ 3,842	$ 1,370	$ 12,619