Commitments and Contingencies Contractual Obligations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Commitments [Line Items]
Provision For Employee Separation Expenses	$ 0	$ 162	$ 1,053	$ 1,355
Construction in Progress [Member]
Other Commitments [Line Items]
Unaccrued Contractual And Other Commitments	$ 115,900		$ 115,900