Receivables - Additional Information Relating to Trouble Debt Restructuring Loan (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Average balance of TDR Loans:
Total average balance of TDR Loans	$ 16,494	$ 16,210
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	310	239
First Mortgage [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	14,730	13,722
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	242	176
Second Mortgage [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	1,190	1,131
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	28	22
Real estate secured [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	15,920	14,853
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	270	198
Personal non-credit card [Member]
Average balance of TDR Loans:
Total average balance of TDR Loans	574	1,357
Interest income recognized on TDR Loans:
Total interest income recognized on TDR Loans	$ 40	$ 41