Annual report pursuant to Section 13 and 15(d)

STOCK-BASED COMPENSATION (Summary of Changes in Nonvested Stock and Weighted-Average Grant Date Fair Value) (Details)

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STOCK-BASED COMPENSATION (Summary of Changes in Nonvested Stock and Weighted-Average Grant Date Fair Value) (Details) - Nonvested Stock - $ / shares
shares in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Shares      
Nonvested at the beginning of the year (in shares) 1,187 1,431 1,700
Granted (in shares) 498 460 472
Vested (in shares) (632) (645) (698)
Forfeited (in shares) (42) (59) (43)
Nonvested at the ending of the year (in shares) 1,011 1,187 1,431
Weighted-Average Grant Date Fair Value      
Nonvested at the beginning of the year (in dollars per share) $ 87.54 $ 72.64 $ 57.52
Granted (in dollars per share) 89.45 84.07 79.26
Vested (in dollars per share) 56.53 55.28 39.21
Forfeited (in dollars per share) 104.24 73.54 59.05
Nonvested at the ending of the year (in dollars per share) $ 109.48 $ 87.54 $ 72.64