Consolidated Statements of Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Interest income:
Loans, including fees	$ 150,481	$ 158,715	$ 453,066	$ 478,751
Loans held for sale	197	177	544	774
Securities-taxable	20,824	21,318	64,601	62,242
Securities-tax exempt	954	1,176	2,946	3,615
Federal funds sold and other short term investments	245	253	685	1,178
Total interest income	172,701	181,639	521,842	546,560
Interest expense:
Deposits	5,828	5,851	16,431	18,785
Short-term borrowings	238	1,074	2,109	3,448
Long-term debt and other interest expense	3,094	3,184	9,421	9,603
Total interest expense	9,160	10,109	27,961	31,836
Net interest income	163,541	171,530	493,881	514,724
Provision for loan losses	9,468	7,569	24,122	25,404
Net interest income after provision for loan losses	154,073	163,961	469,759	489,320
Noninterest income:
Service charges on deposit accounts	20,000	20,519	57,981	59,398
Trust fees	11,530	9,477	33,267	27,972
Bank card and ATM fees	11,641	12,221	33,806	34,678
Investment and annuity fees	5,506	5,186	15,555	14,955
Secondary mortgage market operations	2,313	2,467	6,036	10,989
Insurance commissions and fees	1,979	3,661	7,611	12,500
Amortization of FDIC loss share receivable	(2,760)	(590)	(9,989)	(590)
Other income	7,732	10,116	26,771	27,239
Total noninterest income	57,941	63,057	171,038	187,141
Noninterest expense:
Compensation expense	69,207	73,037	204,900	215,715
Employee benefits	11,957	16,340	38,812	49,184
Personnel expense	81,164	89,377	243,712	264,899
Net occupancy expense	10,848	12,369	32,983	37,099
Equipment expense	4,619	5,127	12,958	15,347
Data processing expense	13,004	12,031	38,310	36,346
Professional services expense	7,229	10,899	22,817	27,571
Amortization of intangibles	6,570	7,306	20,352	22,292
Telecommunications and postage	3,648	4,397	11,094	13,484
Deposit insurance and regulatory fees	2,967	3,789	8,677	11,635
Other real estate expense, net	(104)	2,439	1,757	6,502
Other expense	19,134	34,471	60,259	68,882
Total noninterest expense	149,079	182,205	452,919	504,057
Income before income taxes	62,935	44,813	187,878	172,404
Income taxes	16,382	11,611	52,248	43,764
Net income	$ 46,553	$ 33,202	$ 135,630	$ 128,640
Basic earnings per common share	$ 0.56	$ 0.40	$ 1.62	$ 1.51
Diluted earnings per common share	$ 0.56	$ 0.40	$ 1.62	$ 1.51
Dividends paid per share	$ 0.24	$ 0.24	$ 0.72	$ 0.72
Weighted average shares outstanding-basic	81,721	82,091	81,965	83,404
Weighted average shares outstanding-diluted	81,942	82,205	82,204	83,496