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SHARE-BASED COMPENSATION (Stock Option Activity) (Details) - Stock Options
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
$ / shares
shares
Share-based Compensation  
Option expiration term 10 years
Options granted to vesting employees vesting per year (as a percent) 25.00%
Option vesting period 4 years
Stock Option Plans Activity and Related Information, Shares  
Outstanding beginning of period, shares | shares 1,455
Granted, shares | shares 192
Exercised, shares | shares (256)
Forfeited, shares | shares (2)
Expired, shares | shares (1)
Outstanding end of period, shares | shares 1,388
Expected to vest after applying forfeiture rate, shares | shares 1,371
Vested and exercisable end of period, shares | shares 903
Stock Option Plans Activity and Related Information, Weighted Average Exercise Price  
Outstanding beginning of period, weighted-average exercise price (in dollars per share) | $ / shares $ 25.02
Granted, weighted-average exercise price (in dollars per share) | $ / shares 42.49
Exercised, weighted-average exercise price (in dollars per share) | $ / shares 17.56
Forfeited, weighted-average exercise price (in dollars per share) | $ / shares 35.99
Expired, weighted-average exercise price (in dollars per share) | $ / shares 43.27
Outstanding end of period, weighted-average exercise price (in dollars per share) | $ / shares 28.79
Expected to vest after applying forfeiture rate, weighted-average exercise price (in dollars per share) | $ / shares 28.69
Vested and exercisable end of period, weighted-average exercise price (in dollars per share) | $ / shares $ 24.73
Summary of Weighted Average Remaining Contractual Term and Aggregate Intrinsic Value  
Outstanding end of period, weighted-average remaining contractual term 5 years 5 months 15 days
Outstanding end of period, aggregate intrinsic value | $ $ 23,756
Expected to vest after applying forfeiture rate, weighted-average remaining contractual term 5 years 5 months 1 day
Expected to vest after applying forfeiture rate, aggregate intrinsic value | $ $ 23,600
Vested and exercisable end of period, weighted-average remaining contractual term 4 years 29 days
Vested and exercisable end of period, aggregate intrinsic value | $ $ 19,119