STOCKHOLDERS' EQUITY - Repurchase of Common Stock (Details) - $ / shares	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Number of shares authorized to be repurchased (in shares)	3,763,038
Aggregate number of shares repurchased since inception (in shares)	2,199,268
Number of shares remaining in treasury (in shares)	0		706
Number of shares acquired under stock repurchase plan and subsequently reissued (in shares)	8,496	14,862
Treasury stock acquired, average cost (in dollars per share)	$ 85.53	$ 82.22