(Gain) Loss on Write-Down and Disposal of Long-Lived Assets Impairment Charges - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property	$ (800)	$ 1,000	$ 1,200
Proceeds from sale of discontinued operations			3,400
Gain (Loss) on Sale of Properties			1,900
Cost of sales	840,066	924,276	860,744
Asset Impairment Charges	18,900	700	200
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down	19,710	1,660	(992)
Corporate
Property, Plant and Equipment [Line Items]
Asset Impairment Charges	8,900
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down	10,392	1,518	403
Solid Capacitors
Property, Plant and Equipment [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property			(600)
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down	1,538	235	689
Film and Electrolytic
Property, Plant and Equipment [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property			(3,600)
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down	7,780	(93)	(3,356)
KFM [Member]
Property, Plant and Equipment [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property			(1,400)
Electro-magnetic, Sensors & Actuators [Member]
Property, Plant and Equipment [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property			(1,300)
Disposal Group, Not Discontinued Operation, Loss (Gain) on Write-down	0	0	1,272
Machinery and equipment | Solid Capacitors
Property, Plant and Equipment [Line Items]
Asset Impairment Charges	1,400
Machinery and equipment | Film and Electrolytic
Property, Plant and Equipment [Line Items]
Asset Impairment Charges	6,100
Buildings | Corporate
Property, Plant and Equipment [Line Items]
Asset Impairment Charges	800
Buildings | Film and Electrolytic
Property, Plant and Equipment [Line Items]
Asset Impairment Charges	$ 900
TOKIN | Land
Property, Plant and Equipment [Line Items]
Asset Impairment Charges		500
TOKIN | Machinery and equipment
Property, Plant and Equipment [Line Items]
Asset Impairment Charges		$ 200
Real Estate
Property, Plant and Equipment [Line Items]
Cost of sales			$ 200