Annual report pursuant to Section 13 and 15(d)

STOCK BASED AND DEFERRED COMPENSATION - Summary of Nonvested (Restricted) Shares and Units Activity (Details)

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STOCK BASED AND DEFERRED COMPENSATION - Summary of Nonvested (Restricted) Shares and Units Activity (Details) - $ / shares
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Nonvested Restricted Share Activity (time-based) [Member]      
Nonvested Restricted Share Activity (time-based and performance-based), Number of Shares [Roll Forward]      
Outstanding at beginning of year (in shares) 962,303 883,707 903,441
Granted (in shares) 430,575 499,865 434,387
Vested (Earned/Released) (in shares) (279,856) (305,359) (318,651)
Forfeited (in shares) [1] (130,370) (115,910) (135,470)
Outstanding at end of year (in shares) 982,652 962,303 883,707
Nonvested Restricted Share Activity (time-based and performance-based), Weighted Average Grant Date Fair Value [Roll Forward]      
Outstanding at beginning of year (in dollars per share) $ 37.00 $ 40.75 $ 37.51
Granted (in dollars per share) 34.45 31.60 40.48
Vested (Earned/Released) (in dollars per share) 38.39 30.87 41.14
Forfeited (in dollars per share) [1] 35.09 36.79 40.53
Outstanding at end of year (in dollars per share) $ 35.59 $ 37.00 $ 40.75
Nonvested Restricted Share Activity (performance- based) [Member]      
Nonvested Restricted Share Activity (time-based and performance-based), Number of Shares [Roll Forward]      
Outstanding at beginning of year (in shares) 184,968 180,770 170,833
Granted (in shares) 154,120 66,698 66,187
Vested (Earned/Released) (in shares) (20,367) (41,665) (56,250)
Forfeited (in shares) [1] (31,716) (20,835) 0
Outstanding at end of year (in shares) 287,005 184,968 180,770
Nonvested Restricted Share Activity (time-based and performance-based), Weighted Average Grant Date Fair Value [Roll Forward]      
Outstanding at beginning of year (in dollars per share) $ 34.84 $ 42.93 $ 35.43
Granted (in dollars per share) 34.10 34.39 41.17
Vested (Earned/Released) (in dollars per share) 45.60 31.02 40.34
Forfeited (in dollars per share) [1] 45.60 42.56  
Outstanding at end of year (in dollars per share) $ 35.80 $ 34.84 $ 42.93
[1] Forfeitures on time-based nonvested shares are a result of terminations of employment, while forfeitures on performance-based nonvested shares are a result of failing to attain certain goals as outlined in our executive officers' compensation agreements.