Advances and Other Receivables - Schedule of Accounts Receivable (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Receivables [Abstract]
Servicing advances, net of $63 and $72 purchase discount, respectively	$ 882	$ 975
Receivables from agencies, investors and prior servicers, net of $20 and $21 purchase discount, respectively	162	173
Reserves	(206)	(208)
Total advances and other receivables, net	838	940
Servicing advances discount	63	72	$ 125	$ 131
Receivables discount	$ 20	$ 21	$ 21	$ 21