Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses
Individually evaluated for impairment	$ 271	[1]	$ 294	[1]
Collectively evaluated for impairment	1,403	[1]	1,447	[1]
Loans acquired with deteriorated credit quality	1	[1]	2	[1]
Unallocated	108	[1]	111	[1]
Total allowance for loan and lease losses	1,783	[2]	1,854	[2]	2,126	2,255
Individually evaluated for impairment	2,758	[3]	2,822	[4]
Collectively evaluated for impairment	82,830	[3]	82,877	[4]
Loans acquired with deteriorated credit quality	7	[3]	7	[4]
Total Loans and Leases	85,595	[3],[5],[6]	85,706	[7],[8]
Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Individually evaluated for impairment	75	[1]	95	[1]
Collectively evaluated for impairment	1,116	[1]	1,140	[1]
Loans acquired with deteriorated credit quality			1	[1]
Total allowance for loan and lease losses	1,191	[1]	1,236	[1]	1,424	1,527
Individually evaluated for impairment	901	[3]	980	[4]
Collectively evaluated for impairment	48,883	[3]	48,407	[4]
Loans acquired with deteriorated credit quality	1	[3]	1	[4]
Total Loans and Leases	49,785	[3]	49,388	[4]
Residential Mortgage Loans
Financing Receivable, Allowance for Credit Losses
Individually evaluated for impairment	132	[1]	137	[1]
Collectively evaluated for impairment	79	[1]	91	[1]
Loans acquired with deteriorated credit quality	1	[1]	1	[1]
Total allowance for loan and lease losses	212	[1]	229	[1]	233	227
Individually evaluated for impairment	1,312	[3]	1,298	[4]
Collectively evaluated for impairment	10,692	[3]	10,637	[4]
Loans acquired with deteriorated credit quality	6	[3]	6	[4]
Total Loans and Leases	12,010	[3]	11,941	[4]
Consumer Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Individually evaluated for impairment	64	[1]	62	[1]
Collectively evaluated for impairment	208	[1]	216	[1]
Total allowance for loan and lease losses	272	[1]	278	[1]	341	365
Individually evaluated for impairment	545	[3]	544	[4]
Collectively evaluated for impairment	23,255	[3]	23,833	[4]
Total Loans and Leases	23,800	[3]	24,377	[4]
Unallocated
Financing Receivable, Allowance for Credit Losses
Unallocated	108	[1]	111	[1]
Total allowance for loan and lease losses	$ 108	[1]	$ 111	[1]	$ 128	$ 136

[1] Includes $11 related to leveraged leases.

[2] Includes $50 and $50 of commercial mortgage loans, $(13) and $(5) of ALLL, $1 and $3 of other assets from consolidated VIEs that are included in their respective captions above at March 31, 2013 and December 31, 2012, respectively. See Note 8.

[3] Excludes $81 of residential mortgage loans measured at fair value, and includes $866 of leveraged leases, net of unearned income.

[4] Excludes $76 of residential mortgage loans measured at fair value, and includes $862 of leveraged leases, net of unearned income.

[5] Excludes $81 of loans measured at fair value.

[6] 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 SBA at March 31, 2013.

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

[8] Includes an immaterial amount of government insured commercial loans 30-89 and 90 days past due and accruing whose repayments are insured by the SBA at December 31, 2012.