Loans And Allowance For Loan Losses (Summary Of Loans, Net Of Unearned Income) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	$ 4,520,821	$ 4,439,493
Loans, net of unearned income	8,209,286	8,137,719
Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	2,678,523	2,707,046
Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	1,710,798	1,602,314
Commercial leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	131,500	130,133
Direct installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,192,426	1,178,530
Residential mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,072,898	1,092,228
Indirect installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	574,121	582,037
Consumer lines of credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	817,412	805,494
Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	31,608	39,937
Originated loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	4,228,837	4,133,905
Loans, net of unearned income	7,366,492	7,237,391
Originated loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	2,429,277	2,448,471
Loans, net of unearned income	2,429,277	2,448,471
Originated loans [Member] | Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	1,668,060	1,555,301
Loans, net of unearned income	1,668,060	1,555,301
Originated loans [Member] | Commercial leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	131,500	130,133
Loans, net of unearned income	131,500	130,133
Originated loans [Member] | Direct installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,130,096	1,108,865
Originated loans [Member] | Residential mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	663,781	653,826
Originated loans [Member] | Indirect installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	562,824	568,324
Originated loans [Member] | Consumer lines of credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	749,346	732,534
Originated loans [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	31,608	39,937
Acquired loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	291,984	305,588
Loans, net of unearned income	842,794	900,328
Acquired loans [Member] | Commercial real estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	249,246	258,575
Loans, net of unearned income	249,246	258,575
Acquired loans [Member] | Commercial and industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases	42,738	47,013
Loans, net of unearned income	42,738	47,013
Acquired loans [Member] | Commercial leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total commercial loans and leases
Loans, net of unearned income
Acquired loans [Member] | Direct installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	62,330	69,665
Acquired loans [Member] | Residential mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	409,117	438,402
Acquired loans [Member] | Indirect installment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	11,297	13,713
Acquired loans [Member] | Consumer lines of credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	68,066	72,960
Acquired loans [Member] | Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income