Receivables Held for Investment, net - Additional Information Relating to Trouble Debt Restructuring Loan (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Average balance of TDR Loans held for investment and held for sale:
Total average balance of TDR Loans	$ 3,909	$ 9,085	$ 5,695	$ 10,266
Interest income recognized on TDR Loans held for investment and held for sale:
Total interest income recognized on TDR Loans	80	191	330	590
First lien [Member]
Average balance of TDR Loans held for investment and held for sale:
Total average balance of TDR Loans	3,281	8,281	4,998	9,408
Interest income recognized on TDR Loans held for investment and held for sale:
Total interest income recognized on TDR Loans	63	170	275	525
Second lien [Member]
Average balance of TDR Loans held for investment and held for sale:
Total average balance of TDR Loans	628	804	697	858
Interest income recognized on TDR Loans held for investment and held for sale:
Total interest income recognized on TDR Loans	$ 17	$ 21	$ 55	$ 65