EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net income	$ 19,455	$ 18,594	$ 17,451	$ 9,460	$ 15,978	$ 15,738	$ 14,746	$ 13,383	$ 64,960	$ 59,845	$ 50,254
Weighted Average Shares (in shares)
Basic Shares (in shares)	26,238,004	26,200,621	26,149,593	24,959,865	23,968,320	23,911,678	23,897,413	23,819,065	25,891,382	23,899,562	23,011,814
Effect of dilutive securities (in shares)	52,772	63,493	71,819	80,215	86,812	90,685	94,560	100,173	68,566	93,815	76,764
Weighted average common shares (diluted) (in shares)	26,290,776	26,264,114	26,221,412	25,040,080	24,055,132	24,002,363	23,991,973	23,919,238	25,959,948	23,993,377.000	23,088,578
Net Income Available to Common Shareholders per Share (in dollars per share)
Basic EPS (in dollars per share)	$ 0.74	$ 0.71	$ 0.67	$ 0.38	$ 0.67	$ 0.66	$ 0.62	$ 0.56	$ 2.51	$ 2.50	$ 2.18
Effect of Dilutive Securities (in dollars per share)									(0.01)	(0.01)
Diluted EPS (in dollars per share)	$ 0.74	$ 0.71	$ 0.67	$ 0.38	$ 0.66	$ 0.66	$ 0.61	$ 0.56	$ 2.50	$ 2.49	$ 2.18