Commitments and Contingencies Contractual Obligations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Other Commitments [Line Items]
Provision For Employee Separation Expenses	$ 1,053	$ 658	$ 1,053	$ 1,193
Construction in Progress [Member]
Other Commitments [Line Items]
Unaccrued Contractual And Other Commitments	$ 148,000		$ 148,000