Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Tax loss carryforwards	$ 52,504	$ 54,551
Tax credit carryforwards	19	19
Uniform capitalization, contract and inventory related reserves	1,558	1,728
Accrued vacation	592	669
Stock-based compensation	1,466	1,428
Capitalized research and development	6,212	0
Tax basis depreciation less book depreciation	1,019	0
Intangible assets	1,533	1,364
Deferred revenue	254	149
Accrued foreign taxes	1,271	0
Unrealized gains and losses	0	1,780
Other	2,527	2,668
Total	68,955	64,356
Deferred tax liabilities:
Inventory deduction	(235)	(206)
Pension assets	(1,173)	(1,476)
Allowance for doubtful accounts	(378)	(407)
Tax basis depreciation less book depreciation	0	(192)
Withholding tax on undistributed earnings of foreign subsidiary	(3,675)	(1,590)
Unrealized gains and losses	(984)	0
Other	(1)	(241)
Total	(6,446)	(4,112)
Net deferred tax assets before valuation allowance	62,509	60,244
Valuation allowance	(68,093)	(64,199)
Net deferred tax liabilities	$ (5,584)	$ (3,955)