Loss Contingencies (Narratives) (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Sep. 30, 2017	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Loss Contingencies [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Contingent Liability	$ 0		$ 0		$ 0	$ 1,523,000
Loss Contingency Accrual, Product Liability, Gross	1,074,000		1,074,000
Loss Contingency Alleged Taxes Owed			8,300,000
Loss Contingency Alleged Taxes Owed Including Penalties And Interest			3,500,000
Environmental Expense and Liabilities			804,000
Accrual for Environmental Loss Contingencies	283,000		283,000
Aggregate amount of reserves	13,582,000		13,582,000		13,335,000	$ 14,535,000	$ 12,530,000
Per occurrence limits on self-insurance for general and product liability coverage	2,000,000		2,000,000
Per occurrence limits on self-insurance for general and product liability coverage for 2014 and thereafter	3,000,000		3,000,000
Coverage minimum	2,000,000		2,000,000
Coverage maximum	6,000,000		$ 6,000,000
Claims maximum period			37 years
Asbestos related aggregate liability	6,235,000,000		$ 6,235,000,000
Estimated asbestos related liability payments over the next 12 months	2,000,000		2,000,000
Insurance Recoveries	621,000	$ 1,741,000
Product related aggregate liability	6,273,000,000		6,273,000,000
Minimum
Loss Contingencies [Line Items]
Asbestos-related aggregate liability - Maximum	4,000,000		4,000,000
Maximum
Loss Contingencies [Line Items]
Asbestos-related aggregate liability - Maximum	7,700,000		7,700,000
Other Noncurrent Liabilities [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual, Product Liability, Gross	10,082,000		10,082,000		$ 9,835,000
Accrued Liabilities
Loss Contingencies [Line Items]
Loss Contingency Accrual, Product Liability, Gross	$ 3,500,000		3,500,000
Tax Year 2003/2004 [Member] | Minimum
Loss Contingencies [Line Items]
Loss Contingency Alleged Taxes Owed			2,300,000
Tax Year 2003/2004 [Member] | Maximum
Loss Contingencies [Line Items]
Loss Contingency Alleged Taxes Owed			$ 3,200,000
Magnetek [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies				$ 400,000