Advances and Other Receivables, Net - Advances and Other Receivables Roll Forward (Details) - Reserves for Advances and Other Receivables - 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
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance - beginning of period		$ 0	$ 98		$ 47
Provision and other additions		20	35		102
Write-offs		0	(3)		(19)
Balance - end of period	$ 0	20	$ 130	$ 0	$ 130
Nationstar Mortgage Holdings Inc.
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance - beginning of period	294	$ 297		284
Provision and other additions	7			69
Write-offs	(4)			(56)
Balance - end of period	$ 297			$ 297