Summary of Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 165,898	$ 160,577	$ 159,266
Less - Accumulated depreciation and amortization	(117,127)	(109,657)	(109,859)
Net property, plant and equipment	48,771	50,920	49,407
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment	5,738	5,738	5,888
Buildings, leasehold interests and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment	40,214	40,893	42,854
Machinery, equipment and other
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 119,946	$ 113,946	$ 110,524