Receivables, net - Receivables and Receivables held for Sale (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Modifications, primarily interest rate modifications	$ 56	$ 60
Re-age of past due account	56	91
Total	112	151
First lien [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	18	125
Second lien [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	23	16
Real Estate Secured Receivables Held for Sale [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	71	10
Real estate secured [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 112	$ 151