Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details 3) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Significant components of deferred tax assets and liabilities
Post-retirement benefits	$ 1,837	$ 1,953
Inventory reserves	1,797	1,567
Loss carry-forwards	9,387	23,095
Credit carry-forwards	35,082	16,903
Nondeductible accruals	12,406	6,336
Research expenditures	30,465	30,088
Equity compensation	2,070	1,610
Foreign exchange loss	2,522	1,009
Other	1,231	2,537
Gross deferred tax assets	96,797	85,098
Depreciation	9,814	11,073
Pensions	11,868	9,462
Subsidiaries' unremitted earnings	7,461	0
Gross deferred tax liabilities	29,143	20,535
Net deferred tax assets	67,654	64,563
Deferred tax asset valuation allowance	(10,266)	(12,938)
Total net deferred tax assets	$ 57,388	$ 51,625