Reverse Mortgage Interests, Net - Reserves Roll Forward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reverse Mortgage Interests Reserves [Roll Forward]
Balance - beginning of period	$ 3	$ 13
Provision (release), net	0	0
Write-offs	0	(5)
Balance - end of period	$ 3	$ 8