Payables and Other Liabilities - Repurchase Reserves (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Loans Subject to Repurchase Reserve [Roll Forward]
Balance - beginning of period	$ 25	$ 8
Provisions	5	8
Releases	(1)	0
Balance - end of period	$ 29	$ 16