Consolidated Statements Of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Interest income:
Loans, including fees	$ 97,351	$ 98,488
Securities:
Taxable	36,066	31,185
Tax-exempt	22,503	22,733
Interest-bearing deposits	930	1,171
Federal funds sold and resell agreements	15	16
Total interest income	156,865	153,593
Interest expense:
Deposits	4,572	5,951
Federal funds purchased and repurchase agreements	34	131
Junior subordinated deferrable interest debentures	1,674	1,672
Other long-term borrowings	878	4,080
Total interest expense	7,158	11,834
Net interest income	149,707	141,759
Provision for loan losses	1,100	9,450
Net interest income after provision for loan losses	148,607	132,309
Non-interest income:
Trust and investment management fees	20,652	19,471
Service charges on deposit accounts	20,794	21,250
Insurance commissions and fees	12,377	10,494
Interchange and debit card transaction fees	4,117	8,045
Other charges, commissions and fees	7,350	7,228
Net gain (loss) on securities transactions	(491)	5
Other	7,180	5,840
Total non-interest income	71,979	72,333
Non-interest expense:
Salaries and wages	63,702	62,430
Employee benefits	16,701	15,311
Net occupancy	11,797	11,652
Furniture and equipment	13,420	12,281
Deposit insurance	2,497	4,760
Intangible amortization	1,011	1,120
Other	32,912	32,507
Total non-interest expense	142,040	140,061
Income before income taxes	78,546	64,581
Income taxes	17,513	12,653
Net income	$ 61,033	$ 51,928
Earnings per common share:
Basic	$ 0.99	$ 0.85
Diluted	$ 0.99	$ 0.85