GOODWILL AND INTANGIBLE ASSETS - Goodwill Roll-Forward (Details) - USD ($) $ in Thousands	7 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	May 31, 2016
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	$ 4,829,405	$ 4,807,594	$ 1,491,833
Goodwill acquired	28,820	784,668	3,372,170
Effect of foreign currency translation	(49,336)	81,189	(33,006)
Measurement-period adjustments	(1,295)	30,541	(1,592)
Goodwill, balance at end of period	4,807,594	5,703,992	4,829,405
North America
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	4,086,430	4,083,252	779,734
Goodwill acquired	0	784,668	3,318,768
Effect of foreign currency translation	(1,911)	5,060	(3,872)
Measurement-period adjustments	(1,267)	23,511	(8,200)
Goodwill, balance at end of period	4,083,252	4,896,491	4,086,430
Europe
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	471,773	455,300	485,921
Goodwill acquired	28,820	0	0
Effect of foreign currency translation	(45,265)	57,838	(13,737)
Measurement-period adjustments	(28)	0	(411)
Goodwill, balance at end of period	455,300	513,138	471,773
Asia-Pacific
Goodwill [Roll Forward]
Goodwill, balance at beginning of period	271,202	269,042	226,178
Goodwill acquired	0	0	53,402
Effect of foreign currency translation	(2,160)	18,291	(15,397)
Measurement-period adjustments	0	7,030	7,019
Goodwill, balance at end of period	$ 269,042	$ 294,363	$ 271,202