Receivables - Additional Information Relating to Trouble Debt Restructuring Loan (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Average balance of TDR Loans:
Total average balance of TDR Loans	$ 12,317	$ 15,710	$ 16,801
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	877	1,075	1,149
Real estate secured [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	12,317	15,566	15,876
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	877	1,035	975
First Lien [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	11,342	14,430	14,657
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	782	927	871
Second Lien [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	975	1,136	1,219
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	95	108	104
Personal non-credit card [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	0	144	925
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	$ 0	$ 40	$ 174