EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income	$ 22,064	$ 23,852	$ 20,563	$ 20,725	$ 17,179	$ 20,484	$ 20,374	$ 18,611	$ 87,204	$ 76,648	$ 64,960
Weighted Average Shares (in shares)
Basic Shares (in shares)	27,445,739	27,436,792.000	27,257,799.000	27,029,640	26,710,029.000	26,324,316.000	26,304,129.000	26,275,323	27,294,028	26,404,071	25,891,382
Effect of dilutive securities (in shares)	77,615	76,307.000	74,497.000	81,283	60,022.000	53,072.000	47,885.000	43,409	78,076	51,847	68,566
Weighted average common shares (diluted) (in shares)	27,523,354	27,513,099	27,332,296	27,110,923	26,770,051.000	26,377,388.000	26,352,014.000	26,318,732	27,372,104	26,455,918	25,959,948
Net Income Available to Common Shareholders per Share (in dollars per share)
Basic EPS (in dollars per share)	$ 0.80	$ 0.87	$ 0.75	$ 0.77	$ 0.64	$ 0.78	$ 0.77	$ 0.71	$ 3.19	$ 2.90	$ 2.51
Effect of Dilutive Securities (in dollars per share)									0.00	0.00	(0.01)
Diluted EPS (in dollars per share)	$ 0.80	$ 0.87	$ 0.75	$ 0.76	$ 0.64	$ 0.78	$ 0.77	$ 0.71	$ 3.19	$ 2.90	$ 2.50