LONG-TERM INCENTIVE COMPENSATION (Details 2) - Restricted Shares Subject to Service and Performance Conditions	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Restricted shares subject only to a service condition:
Non-vested, beginning balance, shares | shares	153,620
Granted (shares) | shares	157,877
Vested (shares) | shares	(102,367)
Forfeited (shares) | shares	(45,675)
Non-vested, ending balance, shares | shares	163,455
Non-vested, beginning balance, (dollars per share) | $ / shares	$ 55.90
Granted (dollars per share) | $ / shares	54.86
Vested (dollars per share) | $ / shares	56.58
Forfeited (dollars per share) | $ / shares	55.86
Non-vested, ending balance, (dollars per share) | $ / shares	$ 55.87