Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Interest income:
Loans, including fees	$ 415,230	$ 401,364	$ 397,855
Securities:
Taxable	97,873	132,432	127,072
Tax-exempt	122,031	93,412	91,672
Interest-bearing deposits	7,284	4,300	6,357
Federal funds sold and resell agreements	82	104	61
Total interest income	642,500	631,612	623,017
Interest expense:
Deposits	14,459	18,099	22,179
Federal funds purchased and repurchase agreements	121	140	312
Junior subordinated deferrable interest debentures	6,426	6,806	6,783
Other long-term borrowings	939	1,706	11,967
Total interest expense	21,945	26,751	41,241
Net interest income	620,555	604,861	581,776
Provision for loan losses	20,582	10,080	27,445
Net interest income after provision for loan losses	599,973	594,781	554,331
Non-interest income:
Trust and investment management fees	91,375	83,317	78,297
Service charges on deposit accounts	81,432	83,392	86,125
Insurance commissions and fees	43,140	39,948	35,421
Interchange and debit card transaction fees	16,979	16,933	29,625
Other charges, commissions and fees	34,185	30,180	27,750
Net gain (loss) on securities transactions	1,176	4,314	6,414
Other	34,531	30,703	26,370
Total non-interest income	302,818	288,787	290,002
Non-interest expense:
Salaries and wages	273,692	258,752	252,028
Employee benefits	62,407	57,635	52,939
Net occupancy	50,468	48,975	46,968
Furniture and equipment	58,443	55,279	51,469
Deposit insurance	11,682	11,087	12,714
Intangible amortization	3,141	3,896	4,387
Other	152,077	139,469	137,593
Total non-interest expense	611,910	575,093	558,098
Income before income taxes	290,881	308,475	286,235
Income taxes	53,015	70,523	68,700
Net income	237,866	237,952	217,535
Preferred stock dividends	6,719	0	0
Net income available to common shareholders	$ 231,147	$ 237,952	$ 217,535
Earnings per common share:
Basic (in dollars per share)	$ 3.82	$ 3.87	$ 3.55
Diluted (in dollars per share)	$ 3.80	$ 3.86	$ 3.54