LONG-TERM INCENTIVE COMPENSATION (Details 2) - Restricted Shares Subject to Service and Performance Conditions	9 Months Ended
	Sep. 30, 2018 $ / shares shares
Restricted shares subject only to a service condition:
Non-vested, beginning balance, shares | shares	165,918
Granted (shares) | shares	84,829
Vested (shares) | shares	(98,281)
Forfeited (shares) | shares	0
Non-vested, ending balance, shares | shares	152,466
Non-vested, beginning balance, (dollars per share) | $ / shares	$ 55.85
Granted (dollars per share) | $ / shares	55.46
Vested (dollars per share) | $ / shares	55.81
Forfeited (dollars per share) | $ / shares	0.00
Non-vested, ending balance, (dollars per share) | $ / shares	$ 55.66