TREASURY STOCK - Narrative (Details) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017	Oct. 25, 2016
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Stock repurchase program, authorized amount (up to)				$ 150,000,000.0
Amount available for share repurchase under this latest authorization	$ 150,000,000.0
Treasury stock (in shares)	2,900,000		2,900,000
Treasury stock	$ 120,700,000		$ 121,600,000
Treasury stock, average cost per share (in dollars per share)	$ 41.87		$ 41.77
Stock repurchased during period (in shares)	0	0