Payables and Other Liabilities - Repurchase Reserves (Details) - USD ($) $ in Millions	1 Months Ended	2 Months Ended	3 Months Ended	7 Months Ended	9 Months Ended
	Jul. 31, 2018	Sep. 30, 2018	Sep. 30, 2019	Jul. 31, 2018	Sep. 30, 2019
Loans Subject to Repurchase Reserve [Roll Forward]
Balance - beginning of period		$ 9	$ 23		$ 8
Provisions		1	5		21
Releases		(1)	(4)		(5)
Balance - end of period	$ 9	9	$ 24	$ 9	$ 24
Nationstar Mortgage Holdings Inc.
Loans Subject to Repurchase Reserve [Roll Forward]
Balance - beginning of period	9	$ 9		9
Provisions	0			3
Releases	0			(3)
Balance - end of period	$ 9			$ 9