BUSINESS COMBINATIONS - preliminary fair value of identifiable intangible assets (Details) - NRC $ in Thousands	Nov. 01, 2019 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total identified intangible assets	$ 246,200
Total identified intangible assets	303,600
Customer relationships - noncontractual
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total identified intangible assets	$ 193,700
Average Amortization Period	14 years
Customer relationships - contractual
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total identified intangible assets	$ 34,400
Average Amortization Period	7 years
Permits and licenses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total identified intangible assets	$ 8,700
Average Amortization Period	16 years
Tradename
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total identified intangible assets	$ 6,100
Average Amortization Period	2 years
Non-compete agreements
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total identified intangible assets	$ 3,300
Average Amortization Period	2 years
Permits and licenses
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Non-amortizing intangible assets	$ 57,400