INCOME TAXES (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current:
Federal	$ 17,145,000	$ 13,090,000	$ 6,400,000
State and other	375,000	776,000	1,788,000
Deferred:
Federal	10,674,000	7,633,000	3,929,000
State and other	2,191,000	1,566,000	(495,000)
Provision for income taxes	30,385,000	23,065,000	11,622,000
Components of net deferred tax liability [Abstract]
Allowance for loan losses	16,371,000	16,437,000
Employee benefits	6,718,000	5,843,000
Interest rate swap	0	1,243,000
Debt extinguishment	1,821,000	2,111,000
Other	2,169,000	1,440,000
Deferred tax asset	27,079,000	27,074,000
Investment securities	37,386,000	7,487,000
Intangible assets	9,448,000	16,962,000
Loan origination costs	5,041,000	4,397,000
Depreciation	5,779,000	3,700,000
Mortgage servicing rights	678,000	933,000
Pension	2,860,000	4,163,000
Prepaid FDIC insurance	3,079,000	2,913,000
Deferred tax liability	64,271,000	40,555,000
Net deferred tax liability	(37,192,000)	(13,481,000)
State tax net operating loss carry forward	25,700,000
Gross deferred tax asset related to net operating loss carry forward, prior to federal tax expense	1,400,000
Net operating loss carry forward expiration	between 2026 and 2029
Operating loss carry forward utilization period	Expected to be substantially utilized over the next two years and completely utilized over the next five years.
Effective tax rate reconciliation [Abstract]
Federal statutory income tax rate (in hundredths)	35.00%	35.00%	35.00%
Increase (reduction) in taxes resulting from:
Tax-exempt interest (in hundredths)	(7.10%)	(8.30%)	(14.10%)
State income taxes, net of federal benefit (in hundredths)	1.60%	1.80%	1.70%
Other (in hundredths)	(0.10%)	(1.80%)	(0.70%)
Effective income tax rate (in hundredths)	29.40%	26.70%	21.90%
Unrecognized tax benefits [Roll forward]
Unrecognized tax benefits at beginning of year	98,000	708,000	856,000
Changes related to:
Positions taken during the current year	35,000	35,000	79,000
Settlements with taxing authorities	0	(408,000)	0
Lapse of statutes of limitation	0	(237,000)	(227,000)
Unrecognized tax benefits at end of year	133,000	98,000	708,000
Unrecognized tax benefits that would impact effective tax rate, if recognized	100,000
Accrued interest related to tax positions	$ 10,000	$ 20,000	$ 200,000