NET INCOME PER SHARE (DILUTED SHARES TABLE) (Details) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Shares used in basic earnings per share calculation	46,016	45,662	45,944	45,805
Effect of dilutive securities:
Stock options	9	11	9	6
Restricted stock units	374	460	469	395
Performance-based restricted stock units	2	17	2	18
Total effects of dilutive securities	385	488	480	419
Shares used in dilutive earnings per share calculation	46,401	46,150	46,424	46,224