NET EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Earnings (Numerator) [Abstract]
Basic EPS - Net earnings	$ 16,043	$ 14,012	$ 48,096	$ 40,048
Diluted EPS - Net earnings	$ 16,043	$ 14,012	$ 48,096	$ 40,048
Number of Shares (Denominator) [Abstract]
Basic EPS - weighted average common shares outstanding (in shares)	31,906,629	31,566,067	31,803,869	31,483,053
Effect of dilutive securities - stock options, restricted stock, and performance shares (in shares)	334,827	412,736	399,617	404,209
Diluted EPS - weighted average common shares outstanding and effect of stock options, restricted stock, and performance shares (in shares)	32,241,456	31,978,803	32,203,486	31,887,262
Per Share Amount [Abstract]
Basic EPS - Net earnings (in dollars per share)	$ 0.50	$ 0.44	$ 1.51	$ 1.27
Diluted EPS - Net earnings (in dollars per share)	$ 0.50	$ 0.44	$ 1.49	$ 1.26
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive stock options outstanding, excluded from diluted earnings per share calculation (in shares)			200,610	332,560