Inventories inventories - narrative (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Feb. 01, 2017	Dec. 31, 2016
Inventory Disclosure - Narrative [Abstract]
Inventories						$ 214,900
Inventory Valuation Reserves	$ 317,195		$ 317,195				$ 332,518
Lower of cost or market inventory valuation adjustment	$ (111,128)	$ 312	$ (15,323)	$ (194,282)
Contractual Obligation					$ 30,500