Annual report pursuant to Section 13 and 15(d)

Restructuring - Summary of Restructuring Plans (Details)

v3.19.1
Restructuring - Summary of Restructuring Plans (Details) - USD ($)
$ in Thousands
12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2017
Restructuring Cost and Reserve [Line Items]      
Restructuring charges $ 8,779 $ 14,843 $ 5,404
Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 2,823 12,587 2,214
Manufacturing Relocation [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 5,956 2,256 3,190
Electro-magnetic, Sensors & Actuators [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 452 3,343 0
TOKIN | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Total expected to be incurred 5,339    
Restructuring and Related Cost, Incurred Cost 942    
Cumulative incurred to date 5,339    
TOKIN | Relocation & Exit Costs      
Restructuring Cost and Reserve [Line Items]      
Total expected to be incurred 0    
Restructuring and Related Cost, Incurred Cost 0    
Cumulative incurred to date 0    
Solid Capacitors      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 4,922 983 1,333
Other Restructuring [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 600    
Other Restructuring [Member] | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 300    
Other Restructuring [Member] | Manufacturing Relocation [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 300    
Film and Electrolytic      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 2,717 $ 5,788 3,738
Film and Electrolytic | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 300    
Film and Electrolytic | Manufacturing Relocation [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     $ 600
TOKIN | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 900    
TOKIN | Electro-magnetic, Sensors & Actuators [Member] | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Cumulative incurred to date 3,800    
TOKIN | Solid Capacitors | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Cumulative incurred to date 100    
Corporate | TOKIN | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Cumulative incurred to date 1,400    
NEVADA | Solid Capacitors | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Total expected to be incurred 850    
Restructuring and Related Cost, Incurred Cost 0    
Cumulative incurred to date 0    
NEVADA | Solid Capacitors | Relocation & Exit Costs      
Restructuring Cost and Reserve [Line Items]      
Total expected to be incurred 2,468    
Restructuring and Related Cost, Incurred Cost 3,355    
Cumulative incurred to date 3,355    
NEVADA | Solid Capacitors | Manufacturing Relocation [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 3,400    
Granna, Sweden [Member] | Film and Electrolytic | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Total expected to be incurred 879    
Restructuring and Related Cost, Incurred Cost 0    
Cumulative incurred to date 0    
Granna, Sweden [Member] | Film and Electrolytic | Relocation & Exit Costs      
Restructuring Cost and Reserve [Line Items]      
Total expected to be incurred 3,232    
Restructuring and Related Cost, Incurred Cost 2,296    
Cumulative incurred to date 2,296    
Granna, Sweden [Member] | Film and Electrolytic | Manufacturing Relocation [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 2,300    
Reorganization due to decline of MnO2 Products | Solid Capacitors | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Total expected to be incurred 1,798    
Restructuring and Related Cost, Incurred Cost 1,585    
Cumulative incurred to date 1,585    
Reorganization due to decline of MnO2 Products | Solid Capacitors | Relocation & Exit Costs      
Restructuring Cost and Reserve [Line Items]      
Total expected to be incurred 0    
Restructuring and Related Cost, Incurred Cost 0    
Cumulative incurred to date 0    
Tantalum reclaim expected to be recovered 900    
Expected cost recoveries for scrap material [Member] | NEVADA | Solid Capacitors | Relocation & Exit Costs      
Restructuring Cost and Reserve [Line Items]      
Total expected to be incurred $ 900