EQUITY - Treasury Stock (Details)	6 Months Ended
	Jun. 30, 2018 $ / shares shares
Treasury Stock
Repurchase of common stock (in shares)	5,564
Average cost of repurchase (in dollars per share) | $ / shares	$ 56.20
Number of options exercised (in shares)	115,367
Weighted-average exercise price of options exercised (in dollars per share) | $ / shares	$ 30.92
Number of options exercised via net share settlement	36,282