EQUITY - Treasury Stock (Details)	3 Months Ended
	Mar. 31, 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)	66,353
Weighted-average exercise price of options exercised (in dollars per share) | $ / shares	$ 30.09
Number of options exercised via net share settlement	22,570