Contracts and Revenue Recognition Fourth European Renewable Energy Project (Details) - USD ($)	3 Months Ended		6 Months Ended	15 Months Ended
	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2017	Sep. 30, 2018
Change in construction cost estimates	$ (115,200,000)	$ (98,100,000)	$ (112,200,000)	$ 4,000,000
Loss Contingency, Damages Sought, Value			4,800,000
Fourth European renewable project [Member]
Percentage of completion on European renewable energy project			0.66
Change in construction cost estimates	$ (23,800,000)		$ (21,900,000)
Liquidated damages due to schedule delays			6403
Accrued Liabilities [Member] | Fourth European renewable project [Member]
Change in construction cost estimates			$ (8,800,000)