Accounting Principles and Practices (Narratives) (Details)	12 Months Ended
	Mar. 31, 2017 USD ($) Reporting_Unit Segment Collective_Bargaining_Agreement	Mar. 31, 2016 USD ($) Reporting_Unit	Mar. 31, 2015 USD ($)
Accounting Policies [Line Items]
Advertising expenses	$ 1,748,000	$ 1,690,000	$ 2,147,000
Foreign currency exchange (loss) gain	$ 1,232,000	$ 2,215,000	863,000
Number of segments | Segment	1
Number of reporting units | Reporting_Unit	4	4
Percentage of LIFO inventory	29.00%	34.00%
Research and development costs	$ 10,380,000	$ 7,393,000	5,242,000
Term for basic limited warranty	1 year
Impairment of intangible asset	$ 1,125,000	$ 0	$ 0
Building | Prepaid expenses and other
Accounting Policies [Line Items]
Building held for sale	$ 425,000
Minimum
Accounting Policies [Line Items]
Estimated useful life of intangible assets	1 year
Minimum | Building and building equipment
Accounting Policies [Line Items]
Estimated useful lives of property plant and equipment	15 years
Minimum | Vehicles/Equipment
Accounting Policies [Line Items]
Estimated useful lives of property plant and equipment	3 years
Maximum
Accounting Policies [Line Items]
Estimated useful life of intangible assets	25 years
Maximum | Building and building equipment
Accounting Policies [Line Items]
Estimated useful lives of property plant and equipment	40 years
Maximum | Vehicles/Equipment
Accounting Policies [Line Items]
Estimated useful lives of property plant and equipment	18 years
Workforce Subject to Collective Bargaining Arrangements | Unionized Employees Concentration Risk
Accounting Policies [Line Items]
Percentage of employees	10.00%
Number of collective bargaining agreements | Collective_Bargaining_Agreement	3
Magnetek [Member]
Accounting Policies [Line Items]
Research and development costs	$ 212,000