Annual report pursuant to Section 13 and 15(d)

Restructuring - Narrative (Details)

v3.19.1
Restructuring - Narrative (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
Restructuring Reserve, Accrual Adjustment   0  
Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 5,956 2,256 3,190
Restructuring Reserve, Accrual Adjustment   312  
Employee Relocation      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges   200  
Solid Capacitors      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 4,922 983 1,333
Film and Electrolytic      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 2,717 5,788 3,738
Workforce reductions and administrative overhead   5,200  
Film and Electrolytic | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 300    
Film and Electrolytic | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     600
NEVADA | Solid Capacitors | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost 0    
Cumulative incurred to date 0    
NEVADA | Solid Capacitors | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 3,400    
NEVADA | Solid Capacitors | Facility Closing [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost 3,355    
Cumulative incurred to date 3,355    
TOKIN | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges   4,400  
Mexico | Solid Capacitors | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     300
Mexico | Solid Capacitors | Facility Closing [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     600
Mexico | K-Salt [Member] | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     100
Matamoros Mexico [Member] | K-Salt [Member] | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges   800  
TENNESSEE | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     400
TENNESSEE | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     1,900
TENNESSEE | Employee Relocation      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges   400  
Victoria Mexico [Member] | Solid Capacitors | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     100
Restructuring Reserve, Accrual Adjustment   100  
Europe      
Restructuring Cost and Reserve [Line Items]      
Workforce reductions and administrative overhead   200  
Europe | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     300
Sweden | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges   300  
FLORIDA | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges   2,700 300
FLORIDA | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges   $ 900  
SOUTH CAROLINA | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     300
United Kingdom | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     $ 200
Granna, Sweden [Member] | Film and Electrolytic | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost 0    
Cumulative incurred to date 0    
Granna, Sweden [Member] | Film and Electrolytic | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 2,300    
Granna, Sweden [Member] | Film and Electrolytic | Facility Closing [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost 2,296    
Cumulative incurred to date $ 2,296    
Customer Relationships      
Restructuring Cost and Reserve [Line Items]      
Useful life 12 years 3 months 12 days 12 years 3 months 12 days  
TOKIN | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges $ 900    
TOKIN | Solid Capacitors | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Cumulative incurred to date 100    
Reorganization due to decline of MnO2 Products | Solid Capacitors | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost 1,585    
Cumulative incurred to date 1,585    
Reorganization due to decline of MnO2 Products | Solid Capacitors | Facility Closing [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost 0    
Cumulative incurred to date $ 0