Receivables Held For Sale - Allowance for Credit Losses Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 61	$ 86	$ 174	$ 13
Initial valuation allowance for real estate secured receivables transferred to held for sale during the period	0	2	0	6
Increase (decrease) in valuation allowance resulting from changes in fair value	(55)	62	(163)	130
Change in valuation allowance for collections, charged-off, transferred to REO or short sale	(3)	0	(8)	1
Balance at end of period	$ 3	$ 150	$ 3	$ 150