Revenue Recognition (Contract Liabilities) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Change In Contract With Customer, Asset And Liability [Roll Forward]
Contract Assets, Beginning balance	$ 228,579
Contract Liabilities, Current, Beginning balance	202,458
Revenue recognized that was included in contract liabilities at the beginning of the period	(5,567)	$ 3,870
Amounts transferred from contract assets to receivables	1,631	$ (64,402)
Contract Assets, Ending balance	224,850
Contract Liabilities, Current, Ending balance	207,742
Short-term Contract with Customer
Change In Contract With Customer, Asset And Liability [Roll Forward]
Contract Assets, Beginning balance	228,579
Revenue recognized that was included in contract liabilities at the beginning of the period	0
Increase due to revenue recognized in the period in excess of billings	155,444
Increase due to billings arising during the period in excess of revenue recognized	0
Amounts transferred from contract assets to receivables	(154,817)
Other contract asset, net	(4,356)
Long-term Contract with Customer
Change In Contract With Customer, Asset And Liability [Roll Forward]
Contract Assets, Beginning balance	10,967
Revenue recognized that was included in contract liabilities at the beginning of the period	0
Increase due to revenue recognized in the period in excess of billings	0
Increase due to billings arising during the period in excess of revenue recognized	0
Amounts transferred from contract assets to receivables	(2,202)
Other contract asset, net	(19)
Contract Assets, Ending balance	8,746
Short-term Contract with Customer, Liability
Change In Contract With Customer, Asset And Liability [Roll Forward]
Contract Liabilities, Current, Beginning balance	202,458
Revenue recognized that was included in contract liabilities at the beginning of the period	(73,417)
Increase due to revenue recognized in the period in excess of billings	0
Increase due to billings arising during the period in excess of revenue recognized	78,078
Amounts transferred from contract assets to receivables	0
Other contract liability, net	623
Long-term Contract With Customer, Liability
Change In Contract With Customer, Asset And Liability [Roll Forward]
Contract Liabilities, Noncurrent, Beginning balance	1,370
Revenue recognized that was included in contract liabilities at the beginning of the period	0
Increase due to revenue recognized in the period in excess of billings	0
Increase due to billings arising during the period in excess of revenue recognized	0
Amounts transferred from contract assets to receivables	0
Other contract liability, net	(12)
Contract Liabilities, Noncurrent, Ending balance	$ 1,358