Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Jun. 30, 2013	Dec. 31, 2012		Jun. 30, 2012	Dec. 31, 2011
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses	$ 1,677	[1]	$ 1,925		$ 1,735	$ 1,854	[1]	$ 2,016	$ 2,255
Portfolio loans and leases	87,142	[2]				85,706	[3],[4]
Number of Contracts	8,920	[5],[6]	11,498	[5],[6]
Recorded Investment	3,199	[7]				2,823	[8]
Leveraged Leases
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses	10					11
Portfolio loans and leases	875					862
Residential Mortgage Loans
Financing Receivable, Allowance for Credit Losses
Portfolio loans and leases at fair value	89					76
Variable Interest Entity, Primary Beneficiary
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses	11
Number of Contracts	5
Recorded Investment	$ 29

[1] Includes $53 and $0 of cash and due from banks, $50 and $50 of commercial mortgage loans, $1,145 and $0 of automobile loans, $(16) and $(5) of ALLL, $12 and $3 of other assets, $2 and $0 of other liabilities, and $1,198 and $0 of long-term debt from consolidated VIEs that are included in their respective captions above at September 30, 2013 and December 31, 2012, respectively. See Note 9.

[2] Excludes $89 of loans measured at fair value.

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

[4] 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.

[5] Excludes all loans and leases held for sale and loans acquired with deteriorated credit quality.

[6] Represents number of loans post-modification.

[7] Includes $499, $1,233 and $461, respectively, of commercial, residential mortgage and consumer TDRs on accrual status; $241, $83 and $55, respectively, of commercial, residential mortgage and consumer TDRs on nonaccrual status.

[8] Includes $431, $1,175 and $480, respectively, of commercial, residential mortgage and consumer TDRs on accrual status;$177, $123 and $64, respectively, of commercial, residential mortgage and consumer TDRs on nonaccrual status.