Revenue Recognition (Contract Liabilities) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 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	(21,323)	$ (3,410)
Amounts transferred from contract assets to receivables	(36,325)	$ (54,822)
Contract Assets, Ending balance	258,299
Contract Liabilities, Current, Ending balance	219,680
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
Revenue recognized in the period in excess of billings	584,784
Billings arising during the period in excess of revenue recognized	0
Amounts transferred from contract assets to receivables	(544,533)
Other contract asset, net	(10,531)
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
Revenue recognized in the period in excess of billings	0
Billings arising during the period in excess of revenue recognized	0
Amounts transferred from contract assets to receivables	(3,414)
Other contract asset, net	539
Contract Assets, Ending balance	8,092
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	(129,621)
Revenue recognized in the period in excess of billings	0
Billings arising during the period in excess of revenue recognized	148,552
Amounts transferred from contract assets to receivables	0
Other contract liability, net	(1,709)
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
Revenue recognized in the period in excess of billings	0
Billings arising during the period in excess of revenue recognized	0
Amounts transferred from contract assets to receivables	0
Other contract liability, net	248
Contract Liabilities, Noncurrent, Ending balance	$ 1,618