RESTRUCTURING - Rollforward (Details) - Restructuring Plan 2016 - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Restructuring Reserve [Roll Forward]
Restructuring reserve, Beginning balance	$ 1,323	$ 682	$ 682	$ 0
Restructuring charges	0	7,247	16,917	4,417
Cash payments	(195)		(15,754)	(1,160)
Non-cash settlement			(522)	(2,575)
Restructuring reserve, Ending balance	1,128		1,323	682
Employee Severance and Benefits
Restructuring Reserve [Roll Forward]
Restructuring reserve, Beginning balance	229	198	198	0
Restructuring charges	0	1,592	2,827	1,263
Cash payments	(229)		(2,796)	(1,065)
Non-cash settlement			0	0
Restructuring reserve, Ending balance	0		229	198
Asset Impairments
Restructuring Reserve [Roll Forward]
Restructuring reserve, Beginning balance	0	0	0	0
Restructuring charges	0	522	522	2,575
Cash payments	0		0	0
Non-cash settlement			(522)	(2,575)
Restructuring reserve, Ending balance	0		0	0
Lease Loss Reserves and Contractual Obligations
Restructuring Reserve [Roll Forward]
Restructuring reserve, Beginning balance	1,094	$ 484	484	0
Restructuring charges			13,568	579
Cash payments	34		(12,958)	(95)
Non-cash settlement			0	0
Restructuring reserve, Ending balance	$ 1,128		$ 1,094	$ 484