GOODWILL AND INTANGIBLE ASSETS, NET - Intangible assets, net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Intangible Assets, Net
Gross carrying amount	$ 333,787		$ 333,787		$ 333,787
Accumulated amortization	(196,894)		(196,894)		(178,355)
Net book value	136,893		136,893		155,432
Amortization expense for definite lived intangible assets	9,393	$ 12,756	18,539	$ 24,967
2017	33,800		33,800
2018	26,200		26,200
2019	21,800		21,800
2020	18,200		18,200
2021	13,300		13,300
Trademarks and trade names
Intangible Assets, Net
Gross carrying amount	15,354		15,354		15,354
Accumulated amortization	(8,328)		(8,328)		(7,724)
Net book value	7,026		7,026		7,630
Customer related intangible assets
Intangible Assets, Net
Gross carrying amount	277,828		277,828		277,828
Accumulated amortization	(173,452)		(173,452)		(156,980)
Net book value	104,376		104,376		120,848
Operating agreement
Intangible Assets, Net
Gross carrying amount	35,000		35,000		35,000
Accumulated amortization	(12,982)		(12,982)		(12,104)
Net book value	22,018		22,018		22,896
Non-compete agreements
Intangible Assets, Net
Gross carrying amount	1,560		1,560		1,560
Accumulated amortization	(702)		(702)		(507)
Net book value	858		858		1,053
Intellectual property
Intangible Assets, Net
Gross carrying amount	300		300		300
Accumulated amortization	(100)		(100)		(85)
Net book value	200		200		215
Other intangible assets
Intangible Assets, Net
Gross carrying amount	3,745		3,745		3,745
Accumulated amortization	(1,330)		(1,330)		(955)
Net book value	$ 2,415		$ 2,415		$ 2,790
Weighted Average | Trademarks and trade names
Intangible Assets, Net
Weighted average estimated useful life (in years)			13 years
Weighted Average | Customer related intangible assets
Intangible Assets, Net
Weighted average estimated useful life (in years)			10 years
Weighted Average | Operating agreement
Intangible Assets, Net
Weighted average estimated useful life (in years)			20 years
Weighted Average | Non-compete agreements
Intangible Assets, Net
Weighted average estimated useful life (in years)			4 years
Weighted Average | Intellectual property
Intangible Assets, Net
Weighted average estimated useful life (in years)			10 years
Weighted Average | Other intangible assets
Intangible Assets, Net
Weighted average estimated useful life (in years)			5 years