Summary of Significant Accounting Policies - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 136,609	$ 136,416	$ 126,750
Less - Accumulated depreciation and amortization	(101,156)	(100,652)	(99,546)
Net property, plant and equipment	35,453	35,764	27,204
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	5,918	5,838	2,508
Buildings, Leasehold Interests and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	41,014	40,661	34,612
Machinery, Equipment and Other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 89,677	$ 89,917	$ 89,630