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SHARE-BASED COMPENSATION (Restricted Stock Awards and Units) (Details) - Restricted Stock Awards and Units - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Activity of nonvested shares      
Nonvested at the beginning of the period (in shares) 437,697 463,917 715,460
Changes during the period:      
Granted (in shares) 126,204 296,078 173,897
Forfeited (in shares) (31,570) (66,972) (82,373)
Vested (in shares) (134,780) (255,326) (343,067)
Nonvested at the end of the period (in shares) 397,551 437,697 463,917
Weighted Average Grant Date Fair Value      
Nonvested at the beginning of the period (in dollars per share) $ 22.01 $ 17.41 $ 15.77
Changes during the period:      
Granted (in dollars per share) 31.35 23.65 19.50
Forfeited (in dollars per share) 24.89 20.97 16.73
Vested (in dollars per share) 19.81 15.83 15.21
Nonvested at the end of the period (in dollars per share) $ 25.49 $ 22.01 $ 17.41
Additional disclosures      
Weighted-average period for recognition of compensation cost not yet recognized 2 years 8 months    
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options $ 7,000    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value $ 4,224 $ 5,806 $ 7,888
Minimum      
Additional disclosures      
Vesting period 3 years    
Maximum      
Additional disclosures      
Vesting period 5 years