Mortgage Loans Held for Sale and Investment - Narrative (Details) - USD ($)	1 Months Ended	2 Months Ended	7 Months Ended	9 Months Ended
	Jul. 31, 2018	Sep. 30, 2018	Jul. 31, 2018	Sep. 30, 2017	Dec. 31, 2017
Servicing Assets at Fair Value [Line Items]
Mortgage loans held for sale in foreclosure		$ 33,000,000
Sale of mortgage loans held for sale		3,543,000,000
Gain on sale of mortgage loans held for sale		35,000,000
Mortgage loans held for investment in foreclosure		15,000,000
Ginnie Mae Loans
Servicing Assets at Fair Value [Line Items]
Delinquent loans acquired		29,000,000
Delinquent loans securitized or sold		32,000,000
Purchased loans that have re-performed		$ 58,000,000
Mortgage loans held for investment, net
Servicing Assets at Fair Value [Line Items]
Reclassifications from non-accretable discount			$ 1,000,000	$ 1,000,000
Provision for reserves				0
Predecessor
Servicing Assets at Fair Value [Line Items]
Mortgage loans held for sale in foreclosure					$ 51,000,000
Sale of mortgage loans held for sale	$ 1,891,000,000		13,382,000,000	15,470,000,000
Gain on sale of mortgage loans held for sale	$ 13,000,000		127,000,000	363,000,000
Mortgage loans held for investment in foreclosure					$ 22,000,000
Predecessor | Ginnie Mae Loans
Servicing Assets at Fair Value [Line Items]
Delinquent loans acquired			118,000,000	236,000,000
Delinquent loans securitized or sold			$ 154,000,000	253,000,000
Purchased loans that have re-performed				$ 59,000,000