Advances and Other Receivables - Schedule of Accounts Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Receivables [Abstract]
Servicing advances, net of $72 and $131 purchase discount, respectively	$ 975	$ 970
Receivables from agencies, investors and prior servicers, net of $21 and $21 purchase discount, respectively	173	193
Reserves	(208)	(175)
Total advances and other receivables, net	940	988
Servicing advances discount	72	131	$ 205
Receivable discount	$ 21	$ 21	$ 48