Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Jun. 30, 2012	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011	Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	$ 302	[1]		$ 350	[2]	$ 416	[2]
Collectively evaluated for impairment	1,505	[1]		1,767	[2]	1,872	[2]
Loans acquired with deteriorated credit quality	2	[1]		2	[2]	2	[2]
Unallocated	116	[1]		136	[2]	149	[2]
Total allowance for loan and lease losses	1,925	[3]	2,016	2,255	[3]	2,439	[3]	2,614	3,004
Individually evaluated for impairment	2,940	[4]		3,002	[5]	3,043	[6]
Collectively evaluated for impairment	80,035	[4]		77,940	[5]	76,098	[6]
Loans acquired with deteriorated credit quality	8	[4]		11	[5]	13	[6]
Total Loans and Leases	82,983	[4],[7],[8]		80,953	[10],[5],[9]	79,154	[11],[12],[6]
Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	107	[1]		155	[2]	221	[2]
Collectively evaluated for impairment	1,179	[1]		1,371	[2]	1,427	[2]
Loans acquired with deteriorated credit quality	1	[1]		1	[2]	1	[2]
Total allowance for loan and lease losses	1,287	[1]	1,347	1,527	[2]	1,649	[2]	1,764	1,989
Individually evaluated for impairment	1,107	[4]		1,170	[5]	1,225	[6]
Collectively evaluated for impairment	45,805	[4]		44,299	[5]	42,941	[6]
Loans acquired with deteriorated credit quality	1	[4]		3	[5]	3	[6]
Total Loans and Leases	46,913	[4]		45,472	[5]	44,169	[6]
Residential Mortgage Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	134	[1]		130	[2]	130	[2]
Collectively evaluated for impairment	97	[1]		96	[2]	102	[2]
Loans acquired with deteriorated credit quality	1	[1]		1	[2]	1	[2]
Total allowance for loan and lease losses	232	[1]	232	227	[2]	233	[2]	268	310
Individually evaluated for impairment	1,279	[4]		1,258	[5]	1,237	[6]
Collectively evaluated for impairment	10,346	[4]		9,341	[5]	8,940	[6]
Loans acquired with deteriorated credit quality	7	[4]		8	[5]	10	[6]
Total Loans and Leases	11,632	[4]		10,607	[5]	10,187	[6]
Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	61	[1]		65	[2]	65	[2]
Collectively evaluated for impairment	229	[1]		300	[2]	343	[2]
Total allowance for loan and lease losses	290	[1]	316	365	[2]	408	[2]	452	555
Individually evaluated for impairment	554	[4]		574	[5]	581	[6]
Collectively evaluated for impairment	23,884	[4]		24,300	[5]	24,217	[6]
Total Loans and Leases	24,438	[4]		24,874	[5]	24,798	[6]
Unallocated (Member)
Financing Receivable, Allowance for Credit Losses [Line Items]
Unallocated	116	[1]		136	[2]	149	[2]
Total allowance for loan and lease losses	$ 116	[1]	$ 121	$ 136	[2]	$ 149	[2]	$ 130	$ 150

[1] Includes $12 related to leveraged leases.

[2] Includes $14 related to leveraged leases.

[3] Includes $0, $30 and $35 of cash, $0, $7 and $7of other short-term investments, $50, $50 and $29 of commercial mortgage loans, $0, $223 and $228 of home equity loans, $0, $259 and $334 of automobile loans, ($2), ($10) and ($10) of ALLL, $3, $4 and $3 of other assets, $0, $4 and $5 of other liabilities, $0, $191and $270 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2012, December 31, 2011 and September 30, 2011, respectively. See Note 8.

[4] Excludes $76 of residential mortgage loans measured at fair value, and includes $914 of leveraged leases, net of unearned income.

[5] Excludes $65 of residential mortgage loans measured at fair value, and includes $1,022 of leveraged leases, net of unearned income.

[6] Excludes $62 of residential mortgage loans measured at fair value, includes $1,018 of leveraged leases, net of unearned income.

[7] Excludes $76 of loans measured at fair value.

[8] Includes an immaterial amount of government insured commercial loans 30-89 days and 90 days past due and accruing whose repayments are insured by the Small Business Administration at September 30, 2012.

[9] Excludes $65 of loans measured at fair value.

[10] Includes an immaterial amount of government insured commercial loans 30-89 and 90 days past due and accruing whose repayments are insured by the Small Business Administration at December 31, 2011.

[11] Excludes $62 of loans measured at fair value.

[12] Includes $1 of government insured loans 30-89 days past due and accruing of government insured commercial loans whose repayments are insured by the Small Business Administration at September 30, 2011 and an immaterial amount of government insured commercial loans 90 days past due and still accruing.