Reverse Mortgage Interests, Net - Schedule of Reverse Mortgage Interest (Details) - USD ($) $ in Millions	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Reverse Mortgage Interests [Abstract]
Participating interests in HECM mortgage-backed securities (“HMBS”)	$ 3,873		$ 4,282
Other interests securitized	825		994
Unsecuritized interests	1,138		1,117
Purchase discount, net	(127)	$ (129)	(114)	$ (163)	$ (171)	$ (164)
Total reverse mortgage interests, net	$ 5,709		$ 6,279