GOODWILL AND INTANGIBLE ASSETS - SCHEDULE OF GOODWILL BY REPORTING UNIT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill
Balance at beginning of period	$ 170,990	$ 150,630
Additions	592,302	21,985
Impairment	0	0
Foreign Exchange Translation	6,934	(1,625)
Balance at end of period	770,226	170,990
North America
Goodwill
Balance at beginning of period	140,930	140,930
Additions	555,045	0
Impairment	0	0
Foreign Exchange Translation	316	0
Balance at end of period	696,291	140,930
Europe
Goodwill
Balance at beginning of period	30,060	9,700
Additions	37,257	21,985
Impairment	0	0
Foreign Exchange Translation	6,618	(1,625)
Balance at end of period	$ 73,935	$ 30,060