Income Taxes - Components of Deferred Taxes and Uncertain Tax Positions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets
Net operating loss and credit carryforwards	$ 7,763	$ 4,875
Accruals and other timing items	15,824	11,159
Inventories	11,181	15,403
Pensions	12,186	11,303
Valuation allowance	(2,510)	(2,682)
Total deferred tax assets	44,444	40,058
Deferred tax liabilities
Property, plant and equipment	45,300	49,272
Goodwill and other intangible assets	15,716	6,108
U.S. liability on Belgian and German net deferred tax assets	1,095	708
Total deferred tax liabilities	62,111	56,088
Net deferred tax liability	(17,667)	(16,030)
Uncertain tax liabilities that partially offset net operating losses and credit carryforwards	200	200
Net indirect benefits on uncertain tax liabilities	72	61
Reconciliation of the unrecognized income tax benefits
Balance at beginning of year	778	1,187	$ 3,435
Gross increases for tax positions of current year	108	78	75
Lapse of statute of limitations	(101)	(417)	(500)
Settlement of uncertain tax positions		(70)	(1,823)
Balance at end of year	785	778	$ 1,187
Interest and penalties accrued on prior year uncertain positions	23
Interest and penalties accrued on current and prior year uncertain tax positions		33
Interest and penalties reversed due to the expiration of the statute of limitations	3	100
Amount accrued for payment of interest and penalties related to unrecognized tax benefits	300	300
Gross unrecognized tax benefits that would impact effective tax rate	600	600
Unrecognized tax benefits that are reasonably possible to be recognized within the next twelve months	200
Accrued pension and other liabilities
Reconciliation of the unrecognized income tax benefits
Uncertain tax positions	$ 900	$ 900