CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Interest income:
Interest and fees on loans	$ 192,981	$ 178,703	$ 185,119
Interest and dividends on taxable investments	55,634	47,241	40,030
Interest and dividends on nontaxable investments	22,354	22,337	23,633
Total interest income	270,969	248,281	248,782
Interest expense:
Interest on deposits	26,156	30,559	45,776
Interest on borrowings	29,599	30,078	31,353
Interest on subordinated debt held by unconsolidated subsidiary trusts	5,801	5,960	6,153
Total interest expense	61,556	66,597	83,282
Net interest income	209,413	181,684	165,500
Less: provision for loan losses	4,736	7,205	9,790
Net interest income after provision for loan losses	204,677	174,479	155,710
Noninterest income:
Deposit service fees	42,334	43,358	41,285
Other banking services	4,651	5,985	5,841
Benefit trust, administration, consulting and actuarial fees	31,601	29,616	27,771
Wealth management services	10,697	9,833	8,631
(Loss) gain on investment securities and debt extinguishments, net	(61)	0	7
Total noninterest income	89,222	88,792	83,535
Operating expenses:
Salaries and employee benefits	102,278	91,399	92,690
Occupancy and equipment	24,502	22,933	23,185
Data processing and communications	20,525	20,720	20,684
Amortization of intangible assets	4,381	5,957	8,170
Legal and professional fees	5,889	5,532	5,302
Office supplies and postage	5,246	5,469	5,243
Business development and marketing	5,931	5,237	6,086
FDIC insurance premiums	3,920	5,838	8,610
Goodwill Impairment	0	0	3,079
Acquisition expenses and contract termination charges	4,831	1,365	1,621
Other	12,869	12,436	11,508
Total noninterest expenses	190,372	176,886	186,178
Income (Loss) before income taxes	103,527	86,385	53,067
Income taxes	30,385	23,065	11,622
Net income	$ 73,142	$ 63,320	$ 41,445
Basic earnings per share (in dollars per share)	$ 2.03	$ 1.91	$ 1.26
Diluted earnings per share (in dollars per share)	$ 2.01	$ 1.89	$ 1.26
Cash dividends declared per share (in dollars per share)	$ 1.00	$ 0.94	$ 0.88