Restructuring - Summary of Restructuring Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 8,882	$ 8,779	$ 14,843
Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	7,618	2,823	12,587
Manufacturing Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,264	5,956	2,256
Electro-magnetic, Sensors & Actuators [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,516	452	3,343
Solid Capacitors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	517	4,922	983
Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring charges	1,391	688	4,729
Other Restructuring [Member] | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Total expected to be incurred	1,505
Restructuring and Related Cost, Incurred Cost	758
Cumulative incurred to date	1,198
Restructuring charges		300
Other Restructuring [Member] | Relocation & Exit Costs
Restructuring Cost and Reserve [Line Items]
Total expected to be incurred	432
Restructuring and Related Cost, Incurred Cost	23
Cumulative incurred to date	432
Film and Electrolytic
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,458	2,717	$ 5,788
Film and Electrolytic | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	500	300
TOKIN | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5,000
NEVADA | Solid Capacitors | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Total expected to be incurred	1,107
Restructuring and Related Cost, Incurred Cost	1,107
Cumulative incurred to date	1,107
NEVADA | Solid Capacitors | Relocation & Exit Costs
Restructuring Cost and Reserve [Line Items]
Total expected to be incurred	2,606
Restructuring and Related Cost, Incurred Cost	(777)
Cumulative incurred to date	2,580
NEVADA | Solid Capacitors | Manufacturing Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	800	3,400
Granna, Sweden [Member] | Film and Electrolytic | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Total expected to be incurred	732
Restructuring and Related Cost, Incurred Cost	732
Cumulative incurred to date	732
Restructuring charges	700
Granna, Sweden [Member] | Film and Electrolytic | Relocation & Exit Costs
Restructuring Cost and Reserve [Line Items]
Total expected to be incurred	4,313
Restructuring and Related Cost, Incurred Cost	2,018
Cumulative incurred to date	4,313
Granna, Sweden [Member] | Film and Electrolytic | Manufacturing Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,000	2,300
JAPAN | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	5,000
JAPAN | Electro-magnetic, Sensors & Actuators [Member] | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Total expected to be incurred	5,729
Restructuring and Related Cost, Incurred Cost	5,021
Cumulative incurred to date	5,021
JAPAN | TOKIN | Electro-magnetic, Sensors & Actuators [Member] | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	3,500
JAPAN | TOKIN | Corporate | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	$ 1,500
MnO2 product line headcount reduction | Solid Capacitors | Personnel Reduction Costs
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost		$ 1,600