INTANGIBLE ASSETS - Summary of Acquired Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 7,075,611			$ 7,075,611		$ 7,075,027
Accumulated Amortization	(2,674,615)			(2,674,615)		(2,008,573)
Net Carrying Amount	4,400,996			4,400,996		5,066,454
Amortization of Intangible Assets	208,172	$ 426,419		666,041	$ 981,657
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,970,884			5,970,884		5,970,884
Accumulated Amortization	(1,979,595)			(1,979,595)		(1,409,021)
Net Carrying Amount	3,991,289			3,991,289		4,561,863
Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,067,083			1,067,083		1,067,083
Accumulated Amortization	(678,248)			(678,248)		(588,574)
Net Carrying Amount	388,835			388,835		478,509
Other amortizable intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	37,644			37,644		37,060
Accumulated Amortization	(16,772)			(16,772)		(10,978)
Net Carrying Amount	$ 20,872			$ 20,872		$ 26,082
Minimum | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			8 years
Minimum | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			2 years
Minimum | Other amortizable intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			1 year
Maximum | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			18 years
Maximum | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			5 years
Maximum | Other amortizable intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			15 years