EARNINGS PER SHARE (Earnings Per Share Computations) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Basic earnings per common share:
Net income	$ 8,602	$ 9,347	$ 8,819	$ 8,626	$ 8,261	$ 8,447	$ 7,989	$ 5,965	$ 35,394	$ 30,662	$ 24,543
Dividends and accretion of discount on preferred stock									0	0	3,187
Net income available to common shareholders									35,394	30,662	21,356
BASIC WEIGHTED AVERAGE COMMON SHARES									16,323,870	16,204,952	16,120,606
BASIC EARNINGS PER COMMON SHARE	$ 0.53	$ 0.57	$ 0.54	$ 0.53	$ 0.51	$ 0.52	$ 0.49	$ 0.37	$ 2.17	$ 1.89	$ 1.32
Diluted earnings per common share:
Net income	8,602	9,347	8,819	8,626	8,261	8,447	7,989	5,965	35,394	30,662	24,543
Less: Dividends and accretion of discount on preferred stock									0	0	3,187
Net income available to common shareholders									$ 35,394	$ 30,662	$ 21,356
Weighted-average common shares outstanding for basic earnings per common share									16,323,870	16,204,952	16,120,606
Add: Dilutive effect of assumed exercise of Warrant									38,224	10,370	0
Add: Dilutive effect of assumed exercises of stock options and awards									120,843	109,322	93,141
Average shares and dilutive potential common shares									16,482,937	16,324,644	16,213,747
Diluted earnings per common share	$ 0.52	$ 0.57	$ 0.54	$ 0.52	$ 0.50	$ 0.52	$ 0.49	$ 0.37	$ 2.15	$ 1.88	$ 1.32