Loans and Allowance for Credit Losses - Summary of Impaired Loans by Portfolio Class (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment	$ 7,579	$ 7,602
Unpaid Principal Balance	9,974	10,136
Valuation Allowance	541	599
Commitments to Lend Additional Funds	131	112
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment	442	382
Unpaid Principal Balance	883	804
Valuation Allowance	36	36
Commitments to Lend Additional Funds	102	54
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment	556	693
Unpaid Principal Balance	1,113	1,322
Valuation Allowance	30	51
Commitments to Lend Additional Funds	24	40
Residential Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment	2,740	2,767
Unpaid Principal Balance	3,670	3,492
Valuation Allowance	276	308
Commitments to Lend Additional Funds
Credit Card [Member]
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment	272	310
Unpaid Principal Balance	272	310
Valuation Allowance	69	87
Commitments to Lend Additional Funds
Other Retail [Member]
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment	378	391
Unpaid Principal Balance	410	593
Valuation Allowance	56	59
Commitments to Lend Additional Funds	4	14
Total Impaired Loans, Excluding GNMA and Covered Loans [Member]
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment	4,388	4,543
Unpaid Principal Balance	6,348	6,521
Valuation Allowance	467	541
Commitments to Lend Additional Funds	130	108
Loans Purchased from GNMA Mortgage Pools [Member]
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment	2,816	2,607
Unpaid Principal Balance	2,816	2,607
Valuation Allowance	54	28
Commitments to Lend Additional Funds
Covered Loans [Member]
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment	375	452
Unpaid Principal Balance	810	1,008
Valuation Allowance	20	30
Commitments to Lend Additional Funds	$ 1	$ 4