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SHARE-BASED COMPENSATION (Stock Option Activity) (Details) - Stock Options - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Share-based Compensation    
Total unrecognized compensation cost related to nonvested share-based compensation $ 2,300  
Total unrecognized compensation cost, recognized over a weighted-average period 2 years 9 months 21 days  
Intrinsic value of options exercised $ 2,000 $ 1,600
Stock Option Plans Activity and Related Information, Shares    
Outstanding beginning of period, shares 1,388  
Granted, shares 251  
Exercised, shares (86)  
Forfeited, shares (3)  
Outstanding end of period, shares 1,550  
Expected to vest after applying forfeiture rate, shares 1,522  
Vested and exercisable end of period, shares 1,009  
Stock Option Plans Activity and Related Information, Weighted Average Exercise Price    
Outstanding beginning of period, weighted-average exercise price $ 28.79  
Granted, weighted-average exercise price 40.26  
Exercised, weighted-average exercise price 20.88  
Forfeited, weighted-average exercise price 37.21  
Outstanding end of period, weighted-average exercise price 27.26  
Expected to vest after applying forfeiture rate, weighted-average exercise price 30.92  
Vested and exercisable end of period, weighted-average exercise price $ 27.26  
Summary of Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value    
Outstanding at end of period, weighted-average remaining contractual term 5 years 10 months 2 days  
Outstanding at end of period, aggregate intrinsic value $ 21,753  
Expected to vest after applying forfeiture rate, weighted-average remaining contractual term 5 years 9 months 10 days  
Expected to vest after applying forfeiture rate, aggregate intrinsic value $ 21,588  
Vested and exercisable end of period, weighted-average remaining contractual term 4 years 3 months 10 days  
Vested and exercisable end of period, aggregate intrinsic value $ 17,999