BUSINESS COMBINATIONS (Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Thousands	7 Months Ended
	Sep. 30, 2018	Feb. 23, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 514,102		$ 478,523
Veolia Division
Business Acquisition [Line Items]
Accounts receivable	38,193	$ 40,773
Measurement Period Adjustments, Accounts receivable, including unbilled receivables	(2,580)
Inventories and supplies	1,126	1,442
Measurement Period Adjustments, Inventories and supplies	(316)
Prepaid and other current assets	786	1,005
Measurement Period Adjustments, Prepaid expenses and other current assets	(219)
Property, plant and equipment	72,244	72,244
Measurement Period Adjustments, Property, plant and equipment	0
Permits and other intangibles	5,140	5,140
Measurement Period Adjustments, Permits and other intangibles	0
Current liabilities	(18,625)	(15,908)
Measurement Period Adjustments, Current liabilities	(2,717)
Closure and post-closure liabilities	(354)	(604)
Measurement Period Adjustments, Closure and post-closure liabilities	250
Total identifiable net assets	98,510	104,092
Measurement Period Adjustments, Total identifiable net assets	(5,582)
Goodwill	21,490	15,908
Measurement Period Adjustments, Goodwill	5,582
Total purchase price, net of cash acquired	120,000	$ 120,000
Measurement Period Adjustments, Total purchase price, net of cash acquired	$ 0