Summary of Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 159,266	$ 156,761	$ 154,372
Less - Accumulated depreciation and amortization	(109,859)	(104,635)	(102,904)
Net property, plant and equipment	49,407	52,126	51,468
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment	5,888	7,100	7,052
Buildings, leasehold interests and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment	42,854	45,164	45,009
Machinery, equipment and other
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 110,524	$ 104,497	$ 102,311