Receivables Held For Sale - Allowance for Credit Losses Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 13	$ 0	$ 329
Initial valuation allowance for real estate secured receivables transferred to held for sale during the period	11	0	113
Increase in valuation allowance resulting from changes in fair value	263	155	(457)
Change in valuation allowance for receivables sold	(113)	(142)	14
Change in valuation allowance for collections, charged-off, transferred to REO or short sale	0	0	1
Balance at end of period	$ 174	$ 13	$ 0