Summary of the ALLL and Related Loans and Leases Classified by Portfolio Segment (Parenthetical) (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
Allowance for loan and lease losses	$ 1,783	[1]	$ 1,854	[1]	$ 2,126	$ 2,255
Portfolio loans and leases	85,595	[2],[3],[4]	85,706	[5],[6]
Leveraged Leases
Financing Receivable, Allowance for Credit Losses
Allowance for loan and lease losses	11		11
Portfolio loans and leases	866		862
Residential Mortgage Loans
Financing Receivable, Allowance for Credit Losses
Portfolio loans and leases at fair value	$ 81		$ 76

[1] 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.

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

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

[4] 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.

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

[6] 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.