Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accrued Liabilities [Abstract]
Salaries and wages	$ 17,621	$ 19,229
Accrual for compensated absences	9,564	11,330
Employee benefits	10,880	11,525
Pension liability - current portion	2,110	2,141
Postretirement medical benefits - current portion	4,660	4,750
Returns and allowances	14,024	17,265
Interest	942	2,052
Restructuring costs	6,856	1,873
Dividends	5,443	5,098
Workers' compensation	2,086	2,502
Billings in excess of revenue recognized	2,903	2,024
Professional fees	2,093	2,051
Utilities	779	962
Other	11,824	12,347
Total	$ 91,785	$ 95,149