Annual report pursuant to Section 13 and 15(d)

Restructuring - Summary of Restructuring Plans (Details)

v3.20.1
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