Advances and Other Receivables, Net - Advances and Other Receivable Reserves (Details) - USD ($) $ in Millions	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2019	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Provision for inactive and liquidated loans that are no longer part of the MSR portfolio	$ 25	$ 38	$ 62	$ 72
WMIH Corp | Reserves for Advances and Other Receivables
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance - beginning of period	0		47
Provision and other additions	47		160
Write-offs	0		(32)
Balance - end of period	47	0	$ 175
Nationstar Mortgage Holdings Inc. | Reserves for Advances and Other Receivables
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance - beginning of period	$ 297	284
Provision and other additions		69
Write-offs		(56)
Balance - end of period		$ 297		$ 284