Loans and Leases - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Accounts Notes Loans And Financing Receivable [Table][Abstract]
Unamortized premiums and discounts, deferred loan fees and costs, and fair value adjustments	$ 220	$ 169
Unearned Income	624	665
Loans pledged at the FHLB	11,900	11,100
Loans pledged at the FRB	33,700	33,900
Direct Financing Leases	3,100	2,800
Leveraged leases	801	874
Leveraged leases, pre-tax income (loss)	27	25	$ 25
Leveraged leases, tax expense (benefit)	1	9	$ 9
Minimum future lease payments receivable - 2016	715
Minimum future lease payments receivable - 2017	632
Minimum future lease payments receivable - 2018	532
Minimum future lease payments receivable - 2019	449
Minimum future lease payments receivable - 2020	333
Residual value write-downs related to commercial leases	$ 8	$ 4