EARNINGS PER SHARE (Details) (USD $) In Thousands, except 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
Earnings Per Share [Abstract]
Net income	$ 15,978	$ 15,738	$ 14,746	$ 13,383	$ 10,588	$ 14,655	$ 12,758	$ 12,252	$ 59,845	$ 50,254	$ 42,627
Weighted Average Shares (in shares)
Basic Shares (in shares)	23,968,320	23,911,678	23,897,413	23,819,065	23,383,608	22,946,308	22,888,155	22,823,753	23,899,562	23,011,814	21,782,499
Effect of dilutive securities (in shares)	86,812	90,685	94,560	100,173	97,445	100,806	52,144	46,040	93,815	76,764	29,817
Weighted average common shares (diluted) (in shares)	24,055,132	24,002,363	23,991,973	23,919,238	23,481,053	23,047,114	22,940,299	22,869,793	23,993,377	23,088,578	21,812,316
Net Income Available to Common Shareholders per Share (in dollars per share)
Basic EPS (in dollars per share)	$ 0.67	$ 0.66	$ 0.62	$ 0.56	$ 0.45	$ 0.64	$ 0.56	$ 0.54	$ 2.50	$ 2.18	$ 1.96
Effect of Dilutive Securities (in dollars per share)									$ (0.01)		$ (0.01)
Diluted EPS (in dollars per share)	$ 0.66	$ 0.66	$ 0.61	$ 0.56	$ 0.45	$ 0.64	$ 0.56	$ 0.54	$ 2.49	$ 2.18	$ 1.95