Loans (Summary Of Loan Portfolio) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Loans [Line Items]
Loans and Leases Receivable, Gross	$ 11,489,900	$ 10,521,377	$ 10,272,711
Covered loans	657,525	651,368	680,075
Total loans	12,147,425	11,172,745	10,952,786
Total loans, percentage	95.00%	94.00%	94.00%
Covered loans, percentage	5.00%	6.00%	6.00%
Percentage of Loans Net of Unearned Income Including Covered Loans	100.00%	100.00%	100.00%
Commercial Loan [Member]
Loans [Line Items]
Loans and Leases Receivable, Gross	2,771,053	2,498,313	2,337,098
Total loans, percentage	23.00%	22.00%	21.00%
Commercial Real Estate [Member]
Loans [Line Items]
Loans and Leases Receivable, Gross	3,699,712	3,514,261	3,465,321
Total loans, percentage	30.00%	31.00%	32.00%
Home Equity [Member]
Loans [Line Items]
Loans and Leases Receivable, Gross	807,592	862,345	879,180
Total loans, percentage	7.00%	8.00%	8.00%
Residential Real-Estate [Member]
Loans [Line Items]
Loans and Leases Receivable, Gross	376,678	350,289	326,207
Total loans, percentage	3.00%	3.00%	3.00%
Premium Finance Receivables - Commercial [Member]
Loans [Line Items]
Loans and Leases Receivable, Gross	1,982,945	1,412,454	1,417,572
Total loans, percentage	16.00%	13.00%	13.00%
Premium Finance Receivables - Life Insurance [Member]
Loans [Line Items]
Loans and Leases Receivable, Gross	1,665,620	1,695,225	1,671,443
Total loans, percentage	14.00%	15.00%	15.00%
Indirect Consumer [Member]
Loans [Line Items]
Loans and Leases Receivable, Gross	77,378	64,545	62,452
Total loans, percentage	1.00%	1.00%	1.00%
Consumer And Other [Member]
Loans [Line Items]
Loans and Leases Receivable, Gross	$ 108,922	$ 123,945	$ 113,438
Total loans, percentage	1.00%	1.00%	1.00%