EARNINGS PER SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Basic
Net income	$ 8,677	$ 13,333	$ 6,865	$ 9,361	$ 9,207	$ 10,328	$ 7,210	$ 5,406	$ 38,236	$ 32,151	$ 25,659
Weighted average basic shares outstanding									21,537	18,592	18,238
Earnings per share (in dollars per share)									$ 1.78	$ 1.73	$ 1.41
Diluted
Net income	$ 8,677	$ 13,333	$ 6,865	$ 9,361	$ 9,207	$ 10,328	$ 7,210	$ 5,406	$ 38,236	$ 32,151	$ 25,659
Weighted average basic shares outstanding									21,537	18,592	18,238
Dilutive effect of stock options and restricted stock (in shares)									118	84	43
Weighted average diluted shares outstanding	21,673	21,680	21,667	21,586	19,281	18,533	18,483	18,407	21,655	18,676	18,281
Earnings per share (in dollars per share)	$ 0.40	$ 0.61	$ 0.32	$ 0.43	$ 0.48	$ 0.56	$ 0.39	$ 0.29	$ 1.77	$ 1.72	$ 1.40
Anti-dilutive shares excluded from calculation									58	156	266