Reverse Mortgage Interests, Net - Reverse Mortgage Interests, Net (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reverse Mortgage Interest [Line Items]
Participating interests in HECM mortgage-backed securities, net of $58 and $0 premium, respectively	$ 5,664
Other interests securitized, net of $100 and $0 discount, respectively	1,064
Unsecuritized interests, net of $122 and $89 discount, respectively	1,219
Reserves	(13)	$ 0
Total reverse mortgage interests, net	7,934
Other interests securitized, purchase discount	100	117
Unsecuritized interests, purchase discount	$ 122	173
Predecessor
Reverse Mortgage Interest [Line Items]
Participating interests in HECM mortgage-backed securities, net of $58 and $0 premium, respectively			$ 7,107
Other interests securitized, net of $100 and $0 discount, respectively			912
Unsecuritized interests, net of $122 and $89 discount, respectively			2,080
Reserves		$ (129)	(115)	$ (131)
Total reverse mortgage interests, net			9,984
Other interests securitized, purchase discount			0
Unsecuritized interests, purchase discount			$ 89