Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets
Accrued employee benefits and compensation	$ 9,899	$ 9,284
Postretirement benefit obligations	3,335	5,434
Tax loss and credit carryforwards	7,146	9,318
Reserves and accruals	6,361	6,225
Other	2,792	3,474
Total deferred tax assets	29,533	33,735
Less deferred tax asset valuation allowance	(6,388)	(6,202)	$ (7,691)	$ (7,302)
Total deferred tax assets, net of valuation allowance	23,145	27,533
Deferred tax liabilities
Depreciation and amortization	14,965	17,492
Unremitted earnings	7,239	1,150
Other	190	187
Total deferred tax liabilities	22,394	18,829
Net deferred tax asset	$ 751	$ 8,704