Other Assets - (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Assets [Line Items]
Loans subject to repurchase right from Ginnie Mae	$ 266
Accrued revenues	145
Intangible assets	117
Goodwill	23	$ 10
Other	244
Total other assets	$ 795
Predecessor
Other Assets [Line Items]
Loans subject to repurchase right from Ginnie Mae			$ 218
Accrued revenues			148
Intangible assets			19
Goodwill		$ 72	72	$ 74
Other			222
Total other assets			$ 679