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:
Interest and fees on loans	$ 188,197	$ 192,710	$ 192,981
Interest and dividends on taxable investments	54,995	65,165	55,634
Interest and dividends on nontaxable investments	20,967	23,525	22,354
Total interest income	264,159	281,400	270,969
Interest expense:
Interest on deposits	10,732	18,162	26,156
Interest on borrowings	12,813	30,098	29,599
Interest on subordinated debt held by unconsolidated subsidiary trusts	2,520	2,716	5,801
Total interest expense	26,065	50,976	61,556
Net interest income	238,094	230,424	209,413
Provision for loan losses	7,992	9,108	4,736
Net interest income after provision for loan losses	230,102	221,316	204,677
Noninterest income:
Deposit service fees	49,357	46,064	42,334
Other banking services	5,245	4,069	4,651
Employee Benefit Services	38,596	35,946	31,601
Wealth management services	15,550	12,876	10,697
Gain on sales of investment securities, net	80,768	291	30
Loss on debt extinguishments	(87,336)	0	(91)
Total noninterest income	102,180	99,246	89,222
Noninterest expenses:
Salaries and employee benefits	121,629	112,034	102,278
Occupancy and equipment	27,045	25,799	24,502
Data processing and communications	27,186	23,696	20,525
Amortization of intangible assets	4,469	4,607	4,381
Legal and professional fees	7,008	7,950	5,889
Office supplies and postage	6,122	5,742	5,246
Business development and marketing	6,815	5,919	5,931
FDIC insurance premiums	3,829	3,804	3,920
Acquisition expenses	2,181	5,747	4,831
Other	14,971	16,459	12,869
Total noninterest expenses	221,255	211,757	190,372
Income before income taxes	111,027	108,805	103,527
Income taxes	32,198	31,737	30,385
Net income	$ 78,829	$ 77,068	$ 73,142
Basic earnings per share (in dollars per share)	$ 1.96	$ 1.95	$ 2.03
Diluted earnings per share (in dollars per share)	$ 1.94	$ 1.93	$ 2.01