Income Taxes - Components of Deferred Tax Assets And Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carryforwards	$ 98,571	$ 93,364
Stock-based compensation	1,325	1,943
Property, plant and equipment	9,816	13,990
Other	1,139	1,289
Deferred tax assets, gross	110,851	110,586
Less: Valuation allowance	(110,510)	(106,764)
Total deferred tax assets	341	3,822
Deferred tax liabilities:
Property, plant and equipment	(189)	(3,436)
Other	(152)	(386)
Total deferred tax liabilities	(341)	(3,822)
Net deferred tax asset (liability)	$ 0	$ 0