ACQUISITIONS - Acquisition and Integration Expense (Details) - Acquisition and Integration Costs - All Current Acquirees - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Combination, Separately Recognized Transactions [Line Items]
Legal and professional fees	$ 3,059	$ 1,033	$ 6,931
Financial advisory fees	5,087	0	0
Employee costs including redundant salaries and benefits and severance	0	0	2,016
Facilities consolidation and discontinuation	1,323	488	1,401
Bad debt expense and contractual adjustments related to acquired accounts receivable	0	0	5,430
Legal settlement	0	0	334
Other	653	219	1,812
Total	$ 10,122	$ 1,740	$ 17,924