NET EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net Earnings (Numerator) [Abstract]
Basic EPS - Net earnings	$ 16,536	$ 14,150	$ 32,053	$ 26,036
Diluted EPS - Net earnings	$ 16,536	$ 14,150	$ 32,053	$ 26,036
Number of Shares (Denominator) [Abstract]
Basic EPS - weighted average common shares outstanding (in shares)	31,798,773	31,476,298	31,752,489	31,441,545
Effect of dilutive securities - stock options, restricted stock, and performance shares (in shares)	403,782	398,886	442,563	401,052
Diluted EPS - weighted average common shares outstanding and effect of stock options, restricted stock, and performance shares (in shares)	32,202,555	31,875,184	32,195,052	31,842,597
Per Share Amount [Abstract]
Basic EPS - Net earnings (in dollars per share)	$ 0.52	$ 0.45	$ 1.01	$ 0.83
Diluted EPS - Net earnings (in dollars per share)	$ 0.51	$ 0.44	$ 1.00	$ 0.82
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)			230,108	531,132