REVENUE - Contract Balances - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Contract With Customer Asset And Liability [Abstract]
Accounts Receivable Net Current	$ 269,945	$ 342,766
ContractWithCustomerAssetNetCurrent	260,857	330,983
Deferred Revenue, Current	21,208	22,692
Deferred Revenue, Noncurrent	700	1,138
ReceivablesNotGeneratedFromCustomers	9,100	11,800
Contract Liabilities [Member]
Contract Assets or Liabilities Line Items [Line Items}
Beginning Balance		$ 23,830
Satisfaction of Liability	(7,438)
Additional amounts recognized	5,516
Ending Balance	$ 21,908