Loans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 66,705	$ 56,064	$ 66,705	$ 56,064	$ 63,258
Net deferred origination costs	15		15		30
Net unamortized premium on loans	21		21		25
Amortized net premiums on loans	1	9	3	18
Total nonaccruing loans	1,403		1,403		1,629
Current interest income of nonaccrual loans	30	26	61	55
Current interest income (expense) in finance loans	11	2	16	1
Commercial loans removed from TDR classification	11		11
Loans held for sale	359		359		1,018
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	19,441		19,441		19,108
Total nonaccruing loans	1,107		1,107		1,129
Weighted average rate of reduction	2.10%	1.70%	2.10%	1.80%
Loans held for sale	339		339		537
Residential Mortgage [Member] | Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	15,837	14,758	15,837	14,758	15,371
Total nonaccruing loans	1,013		1,013		1,038
Loans held for sale	275		275		472
Parent And Other Subsidiaries Of Common Parent [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 6,967		$ 6,967		$ 4,514