Advances and Other Receivables - Purchase Discount (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Servicing Advances
Balance - beginning of year	$ 131	$ 205
Addition from acquisition	0	19
Utilization of purchase discounts	(59)	(93)
Balance - end of year	72	131
Receivables from Agencies, Investors and Prior Servicers
Balance - beginning of year	21	48
Addition from acquisition	0	0
Utilization of purchase discounts	0	(27)
Balance - end of year	$ 21	$ 21