Loans (Summary Of Loan Portfolio) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 12,581,039	$ 11,828,943	$ 11,489,900
Covered loans	415,988	560,087	657,525
Total loans	12,997,027	12,389,030	12,147,425
Total loans, percentage	97.00%	96.00%	95.00%
Covered loans, percentage	3.00%	4.00%	5.00%
Percentage of Loans Net of Unearned Income Including Covered Loans	100.00%	100.00%	100.00%
Commercial
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	3,109,121	2,914,798	2,771,053
Total loans, percentage	24.00%	24.00%	23.00%
Commercial real-estate
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	4,146,110	3,864,118	3,699,712
Total loans, percentage	32.00%	31.00%	30.00%
Home equity
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	736,620	788,474	807,592
Total loans, percentage	6.00%	6.00%	7.00%
Residential real-estate
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	397,707	367,213	376,678
Total loans, percentage	3.00%	3.00%	3.00%
Premium finance receivables | Commercial insurance loans
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	2,150,481	1,987,856	1,982,945
Total loans, percentage	16.00%	16.00%	16.00%
Premium finance receivables | Premium Finance Receivables Life Insurance [Member]
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	1,869,739	1,725,166	1,665,620
Total loans, percentage	14.00%	14.00%	14.00%
Indirect consumer
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	57,236	77,333	77,378
Total loans, percentage	1.00%	1.00%	1.00%
Consumer and other
Loans [Line Items]
Loans, net of unearned income, excluding covered loans	$ 114,025	$ 103,985	$ 108,922
Total loans, percentage	1.00%	1.00%	1.00%