Loans and Leases - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases net of unearned income	$ 942,000,000	$ 1,000,000,000
Unamortized premiums and discounts, deferred loan fees and costs, and fair value adjustments	45,000,000	(19,000,000)
Direct Financing Leases	2,900,000,000	3,000,000,000
Leveraged leases	1,700,000,000	1,700,000,000
Leveraged leases, pre-tax income (loss)	33,000,000	49,000,000
Leveraged leases, tax expense (benefit)	10,000,000	10,000,000
Minimum future lease payments receivable - 2012	662,000,000
Minimum future lease payments receivable - 2013	561,000,000
Minimum future lease payments receivable - 2014	553,000,000
Minimum future lease payments receivable - 2015	360,000,000
Minimum future lease payments receivable - 2016	76,000,000
Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Residual value write-downs related to leases	$ 4,000,000