Condensed Consolidated Balance Sheets (Parenthetical) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Forward MSRs - fair value	$ 3,354,000,000	$ 2,703,000,000
Advances and other receivables, reserves	206,000,000	208,000,000
Purchase discount, net	93,000,000	127,000,000
Accumulated depreciation	$ 107,000,000	$ 96,000,000
Preferred stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	1,000,000.0	1,000,000.0
Preferred stock, shares outstanding (in shares)	1,000,000.0	1,000,000.0
Preferred stock, liquidation preference	$ 10	$ 10
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares, issued (in shares)	93,200,000	92,000,000.0
Treasury stock (in shares)	7,100,000	2,600,000