Inventories inventories - narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Inventory Disclosure - Narrative [Abstract]
Inventories	$ 213,000		$ 213,000
Inventory Valuation Reserves	428,323		428,323		$ 332,518
Lower of cost or market inventory valuation adjustment	$ 83,982	$ (138,473)	$ 95,805	$ (194,594)
Contractual Obligation		$ 30,500		$ 30,500