Receivables, net - Additional Information Relating to Trouble Debt Restructuring Loan (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Average balance of TDR Loans:
Total average balance of TDR Loans	$ 9,763	$ 12,317	$ 15,710
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	750	877	1,075
First lien [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	8,927	11,342	14,430
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	665	782	927
Second lien [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	836	975	1,136
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	85	95	108
Real Estate Secured [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	9,763	12,317	15,566
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	750	877	1,035
Consumer Loan Excluding Credit Card [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	0	0	144
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	$ 0	$ 0	$ 40