Loan Sales and Servicing Activities - Summary of Cash Flows with Transferees (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Cash flows:
Sales proceeds	$ 21,188,988	$ 12,650,318	$ 40,526,005	$ 21,186,748
Servicing fees received	158,871	140,416	325,427	277,564
Net servicing advances	12,311	$ (8,012)	(2,898)	$ (32,188)
Period end information:
Unpaid principal balance of loans outstanding	182,319,317		182,319,317		$ 168,842,011
30-89 days	12,396,411		12,396,411		7,947,560
90 days or more - Not in foreclosure	16,046,569		16,046,569		3,237,563
90 days or more - In foreclosure	718,689		718,689		888,136
90 days or more - Foreclosed	14,920		14,920		15,387
Bankruptcy	$ 1,384,075		$ 1,384,075		$ 1,343,816