STOCKHOLDERS' EQUITY, Repurchase of Common Stock (Details) - $ / shares	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Repurchase of common stock [Abstract]
Number of shares authorized to be repurchased (in shares)	3,763,038
Aggregate number of shares repurchased since inception (in shares)	2,184,471
Number of shares remaining in treasury (in shares)	0
Number of shares acquired under stock repurchase plan and subsequently reissued (in shares)	10,454	7,175
Treasury stock acquired, average cost (in dollars per share)	$ 75.04	$ 85.18