Advances and Other Receivables, Net - Purchase Discount (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2019
Servicing Advances
Balance - beginning of period	$ 246	$ 156	$ 205
Addition from acquisition	0	0	19
Utilization of purchase discounts	(19)	(8)	(76)
Balance - end of period	227	148	148
Receivables from Agencies, Investors and Prior Servicers
Balance - beginning of period	56	48	48
Addition from acquisition	0	0	0
Utilization of purchase discounts	0	0	0
Balance - end of period	$ 56	$ 48	$ 48