Receivables, net - Receivables Classified as Troubled Debt Restructuring Loan (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Receivables classified as Trouble Debt Restructuring Loans
TDR loans that became delinquent during the period	$ 25	$ 49	$ 53	$ 115
Receivables Held For Sale [Member] | Real Estate Secured [Member]
Receivables classified as Trouble Debt Restructuring Loans
TDR loans that became delinquent during the period	18	37	38	39
First lien [Member]
Receivables classified as Trouble Debt Restructuring Loans
TDR loans that became delinquent during the period	3	7	7	62
Second lien [Member]
Receivables classified as Trouble Debt Restructuring Loans
TDR loans that became delinquent during the period	$ 4	$ 5	$ 8	$ 14