Loans Held for Sale - Summary of Activity in Balance of Loans Held for Sale, at Lower of Cost or Fair Value (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Movement In Loans Held For Sale At Fair Value [Roll Forward]
Beginning balance	$ 66,097	$ 24,096	$ 29,374
Purchases	320,089	770,563	1,016,791
Proceeds from sales	(221,471)	(569,718)	(861,569)
Principal collections	(11,304)	(15,413)	(10,207)
Receivables, net	(104,635)	(155,586)	(171,797)
REO (Other assets)	(4,116)	(2,355)	(875)
Gain on sale of loans	4,974	3,659	11,683
Decrease (increase) in valuation allowance	4,926	(4,251)	2,746
Other	11,957	15,102	7,950
Ending balance	$ 66,517	$ 66,097	$ 24,096