Annual report pursuant to Section 13 and 15(d)

Restructuring - Narrative (Details)

v3.20.1
Restructuring - Narrative (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
Restructuring Reserve, Accrual Adjustment     0
Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 1,264 5,956 2,256
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 517 4,922 983
Tantalum [Member] | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 1,100    
Film and Electrolytic      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 3,458 2,717 5,788
Workforce reductions and administrative overhead     5,200
Film and Electrolytic | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 500 300  
NEVADA | Solid Capacitors | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost 1,107    
Cumulative incurred to date 1,107    
NEVADA | Solid Capacitors | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 800 3,400  
NEVADA | Solid Capacitors | Facility Closing [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost (777)    
Cumulative incurred to date 2,580    
TOKIN | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges   900 4,400
Matamoros Mexico [Member] | K-Salt [Member] | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     800
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 Reserve, Accrual Adjustment     100
Europe      
Restructuring Cost and Reserve [Line Items]      
Workforce reductions and administrative overhead     200
FLORIDA | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     2,700
FLORIDA | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges     $ 900
Granna, Sweden [Member] | Film and Electrolytic | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 700    
Restructuring and Related Cost, Incurred Cost 732    
Cumulative incurred to date 732    
Granna, Sweden [Member] | Film and Electrolytic | Manufacturing and sales office relocation costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges 2,000 $ 2,300  
Granna, Sweden [Member] | Film and Electrolytic | Facility Closing [Member]      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost 2,018    
Cumulative incurred to date $ 4,313    
Customer Relationships      
Restructuring Cost and Reserve [Line Items]      
Useful life 12 years 2 months 12 days 12 years 3 months 12 days  
TOKIN | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring charges $ 5,000    
MnO2 product line headcount reduction | Solid Capacitors | Personnel Reduction Costs      
Restructuring Cost and Reserve [Line Items]      
Restructuring and Related Cost, Incurred Cost   $ 1,600