REVENUE - Contract Balances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Contract with Customer, Asset and Liability [Abstract]
Receivables, included in “Accounts receivable net of allowance for doubtful accounts”	$ 272,321	$ 376,504
Unearned revenue - current	15,651	9,894
Unearned revenue - noncurrent	1,294	$ 2,113
Change in Contract with Customer, Liability [Abstract]
Beginning balance	12,007
Revenue recognized during the period that was included in the beginning balance of contract liabilities	(10,692)
Additional amounts received during period	15,630
Ending balance	$ 16,945