Income Taxes - Schedule of Income Taxes (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
Income Tax Examination [Line Items]
Income (loss) before income tax expense (benefit)		$ 41	$ 107		$ (243)
Income tax expense (benefit)		$ (979)	$ 24		$ (52)
Effective tax rate		(2377.10%)	22.30%		21.50%
Nationstar Mortgage Holdings Inc.
Income Tax Examination [Line Items]
Income (loss) before income tax expense (benefit)	$ (83)			$ 202
Income tax expense (benefit)	$ (19)			$ 48
Effective tax rate	23.10%			23.80%