Loss Contingencies (Narratives) (Details)			3 Months Ended	6 Months Ended	9 Months Ended		12 Months Ended
	Aug. 02, 2012 USD ($)	Aug. 02, 2012 EUR (€)	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)
Loss Contingencies [Line Items]
Loss Contingency Accrual			$ 20,740,000	$ 20,740,000			$ 11,902,000	$ 12,686,000
Loss Contingency Accrual, Product Liability, Gross			20,740,000	20,740,000			11,944,000
Estimation of asbestos-related aggregate liability that is probable and estimable			5,941,000	5,941,000
Estimation of product-related aggregate liability			7,153,000	7,153,000
Loss Contingency Alleged Taxes Owed	$ 7,900,000	€ 6,700,000
Loss Contingency Alleged Taxes Owed Including Penalties And Interest	$ 3,300,000	€ 2,800,000
Accrual for Environmental Loss Contingencies			765,000	765,000
Estimated Litigation Liability			80,000	80,000
Loss Contingency Accrual, Provision				2,655,000			3,233,000
Loss Contingency Accrual, Payments				(772,000)			(3,975,000)
Estimated Insurance Recoveries			6,955,000	6,955,000			0
Loss Contingency Accrual, Product Liability, Net			13,785,000	13,785,000			$ 11,944,000
Loss Contingency Accrual, Period Increase (Decrease)				1,830,000
Gain (Loss) Related to Litigation Settlement			3,006,000
Proceeds from Legal Settlements				2,450,000
Minimum [Member]
Loss Contingencies [Line Items]
Product Liability Contingency, Third Party Recovery				2,000,000
Estimation of asbestos-related aggregate liability that is probable and estimable			5,100,000	5,100,000
Maximum [Member]
Loss Contingencies [Line Items]
Product Liability Contingency, Third Party Recovery				6,000,000
Estimation of asbestos-related aggregate liability that is probable and estimable			9,400,000	9,400,000
Litigation Settlement, Amount Awarded from Other Party				1,650,000
Magnetek [Member]
Loss Contingencies [Line Items]
Estimation of asbestos-related aggregate liability that is probable and estimable			667,000	667,000
Accrual for Environmental Loss Contingencies			453,000	453,000
Fiscal year 2004 [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Product Liability Contingency, Third Party Recovery				3,000,000
Fiscal year 2003 [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Product Liability Contingency, Third Party Recovery				2,000,000
Other Noncurrent Liabilities [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual			17,240,000	17,240,000
Accrued Liabilities
Loss Contingencies [Line Items]
Loss Contingency Accrual, Product Liability, Gross			3,500,000	3,500,000
Gain (Loss) Related to Litigation Settlement			1,200,000
Forecast [Member]
Loss Contingencies [Line Items]
Asbestos liability payments				$ 2,000,000
Loss settlement gross period				12 months
Loss Contingency Alleged Taxes Owed					$ 2,200,000	€ 1,900,000
Loss Contingency Alleged Taxes Owed Including Penalties And Interest					$ 3,000,000	€ 2,600,000
Forecast [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Loss contingency period				37 years
DEP [Member] | Magnetek [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies			$ 283,000	$ 283,000