Reverse Mortgage Interests, Net - Roll Forward (Details) - USD ($) $ in Millions	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2018	Jul. 31, 2018	Dec. 31, 2019
Reverse Mortgage Interests Reserves [Roll Forward]
Balance - beginning of period			$ 13
Balance - end of period	$ 13		3
WMIH Corp
Reverse Mortgage Interests Reserves [Roll Forward]
Balance - beginning of period	0		13
Provision	13		(3)
Write-offs	0		(7)
Balance - end of period	13	$ 0	$ 3
Nationstar Mortgage Holdings Inc.
Reverse Mortgage Interests Reserves [Roll Forward]
Balance - beginning of period	$ 129	115
Provision		32
Write-offs		(18)
Balance - end of period		$ 129