Significant Accounting Policies - Narrative (Details) $ in Millions	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($)	Jul. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) mortgage_loan	Dec. 31, 2017 USD ($)
Derivative [Line Items]
Mortgage loans held for investment | mortgage_loan			0
Mortgage loan sale period			30 days
Number of reporting units			3
Advertising costs | $	$ 17	$ 33	$ 33	$ 57
Minimum
Derivative [Line Items]
Loan commitment period			30 days
Maximum
Derivative [Line Items]
Loan commitment period			90 days