Basis of Presentation and Significant Accounting Policies Allowance for obsolete inventory (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Inventory Write-down & Firm Purchase Commitment	$ 61,472
Balance, beginning of year		$ 13,075	$ 18,852	$ 8,991
Provision for obsolete inventory		5,857	28,903	11,959
Less Charges against allowance		(11,055)	(34,680)	(2,098)
Balance, end of year	$ 13,075	$ 7,877	$ 13,075	$ 18,852