Reverse Mortgage Interests, Net - Reverse Mortgage Interests Roll Forward (Details) - USD ($) $ in Millions	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2017
Reverse Mortgage Interests Reserves [Roll Forward]
Balance - beginning of period	$ 0
Provision	13
Write-offs	0
Balance - end of period	13	$ 0
Predecessor
Reverse Mortgage Interests Reserves [Roll Forward]
Balance - beginning of period	$ 129	115	$ 131
Provision		32	76
Write-offs		(18)	(92)
Balance - end of period		$ 129	$ 115