Assets - Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Property, plant, and equipment
Gross property, plant and equipment	$ 164,877	$ 159,505
Less: accumulated depreciation and amortization	101,193	98,859
Net property, plant and equipment	63,684	60,646
Depreciation	2,900	3,300
Land
Property, plant, and equipment
Gross property, plant and equipment	5,669	5,669
Building and improvements
Property, plant, and equipment
Gross property, plant and equipment	51,102	50,814
Machinery and equipment
Property, plant, and equipment
Gross property, plant and equipment	104,222	99,370
Leaseholds improvements
Property, plant, and equipment
Gross property, plant and equipment	$ 3,884	$ 3,652