Quarterly report pursuant to Section 13 or 15(d)

Concentrations of Risks (Details)

v3.10.0.1
Concentrations of Risks (Details)
$ in Thousands, € in Millions, ¥ in Millions, R$ in Millions, $ in Millions, $ in Millions, ₩ in Billions
3 Months Ended 6 Months Ended
Sep. 16, 2018
USD ($)
Sep. 16, 2018
KRW (₩)
Jun. 27, 2018
USD ($)
Jun. 27, 2018
CAD ($)
Mar. 21, 2018
EUR (€)
Mar. 21, 2018
USD ($)
Jul. 26, 2016
USD ($)
Jul. 26, 2016
BRL (R$)
May 02, 2016
USD ($)
installment
suit
Mar. 29, 2016
USD ($)
Mar. 29, 2016
JPY (¥)
Dec. 09, 2015
USD ($)
Dec. 09, 2015
TWD ($)
Sep. 02, 2015
USD ($)
installment
Jul. 31, 2013
defendant
suit
Sep. 30, 2018
USD ($)
Sep. 30, 2017
Sep. 30, 2018
USD ($)
Sep. 30, 2017
Mar. 31, 2018
USD ($)
Concentration of Risk                                        
Accounts Payable, Trade, Current                               $ 138,253   $ 138,253   $ 139,989
Accrued expenses (1)                               96,666   96,666   125,119
Other non-current obligations (1)                               $ 128,427   $ 128,427   $ 152,249
Revenue from Contract with Customer [Member] | Sales risk                                        
Concentration of Risk                                        
Concentration Risk, Customer                               1        
Revenue from Contract with Customer [Member] | Sales risk | Minimum [Member]                                        
Concentration of Risk                                        
Concentration risk, percentage                               10.00%        
Revenue from Contract with Customer [Member] | Electronics distributor risk                                        
Concentration of Risk                                        
Concentration risk, percentage                                   41.50% 38.60%  
Accounts receivable | Sales risk                                        
Concentration of Risk                                        
Concentration Risk, Customer                               0 0 0 0  
Accounts receivable | Credit Concentration Risk [Member]                                        
Concentration of Risk                                        
Concentration Risk, Customer                                     0  
Accounts receivable | Credit Concentration Risk [Member] | Maximum                                        
Concentration of Risk                                        
Concentration risk, percentage                                   10.00%    
Sales Revenue, Goods, Net [Member] | Sales risk                                        
Concentration of Risk                                        
Concentration Risk, Customer                               1 1 1 1  
Sales Revenue, Goods, Net [Member] | Sales risk | Minimum [Member]                                        
Concentration of Risk                                        
Concentration risk, percentage                               10.00% 10.00% 10.00% 10.00%  
Sales Revenue, Goods, Net [Member] | Electronics distributor risk                                        
Concentration of Risk                                        
Concentration risk, percentage                               41.40% 35.60%      
Indemnification Agreement [Member] | Equity Method Investments [Member]                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party                           $ 13,800            
Settled Litigation [Member] | Indemnification Agreement [Member] | Equity Method Investments [Member]                                        
Concentration of Risk                                        
Litigation Settlement, Payment Period                           5 years            
Litigation Settlement, Number of Payment Installments | installment                           6            
Litigation Settlement, Amount Awarded to Other Party                           $ 2,300            
Japan, Yen | JAPAN                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party | ¥                     ¥ 127.2                  
Taiwan, New Dollars | TAIWAN, PROVINCE OF CHINA                                        
Concentration of Risk                                        
Loss Contingency, Damages Sought, Value                         $ 1,200.0              
Taiwan, New Dollars | TAIWAN, PROVINCE OF CHINA | Minimum [Member]                                        
Concentration of Risk                                        
Loss Contingency, Damages Sought, Value                         $ 609.1              
United States of America, Dollars | TAIWAN, PROVINCE OF CHINA                                        
Concentration of Risk                                        
Loss Contingency, Damages Sought, Value                       $ 39,900                
United States of America, Dollars | TAIWAN, PROVINCE OF CHINA | Minimum [Member]                                        
Concentration of Risk                                        
Loss Contingency, Damages Sought, Value                       $ 19,900                
United States of America, Dollars | JAPAN                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party                   $ 1,100                    
United States of America, Dollars | BRAZIL | Settled Litigation [Member]                                        
Concentration of Risk                                        
Loss Contingency, Damages Paid, Value             $ 200                          
Brazil, Brazil Real | BRAZIL | Settled Litigation [Member]                                        
Concentration of Risk                                        
Loss Contingency, Damages Paid, Value | R$               R$ 0.6                        
TOKIN [Member]                                        
Concentration of Risk                                        
Loss Contingency Accrual                               $ 51,800   $ 51,800    
TOKIN [Member] | United States of America, Dollars | CANADA | Settled Litigation [Member]                                        
Concentration of Risk                                        
Loss Contingency, Damages Paid, Value     $ 2,200                                  
TOKIN [Member] | Canada, Dollars | CANADA | Settled Litigation [Member]                                        
Concentration of Risk                                        
Loss Contingency, Damages Paid, Value       $ 2.9                                
NEC TOKIN Corporation [Member] | Indemnification Agreement [Member] | Equity Method Investments [Member]                                        
Concentration of Risk                                        
Litigation Settlement, Number of Payment Installments | installment                 5                      
Litigation Settlement, Amount Awarded to Other Party                 $ 37,300                      
NEC TOKIN Corporation [Member] | Preliminary Settlement [Member] | Indemnification Agreement [Member] | Equity Method Investments [Member]                                        
Concentration of Risk                                        
Loss Contingency, Pending Claims, Number | suit                 2                      
Unfavorable Regulatory Action [Member]                                        
Concentration of Risk                                        
Accounts Payable, Trade, Current                               10,000   10,000    
Accrued expenses (1)                               19,200   19,200    
Other non-current obligations (1)                               22,600   $ 22,600    
Lithium Ion Batteries Antitrust Litigation [Member]                                        
Concentration of Risk                                        
Loss Contingency, Number of Defendants | defendant                             8          
Loss Contingency, Pending Claims, Number | suit                             2          
Lithium Ion Batteries Antitrust Litigation [Member] | TOKIN [Member]                                        
Concentration of Risk                                        
Loss Contingency, Number of Defendants | defendant                             1          
Battery Action Class Suit - Indirect Product Purchasers [Member]                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party                               2,000        
Battery Action Class Suit [Member]                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party                               $ 4,950        
Competition Laws of the European Union [Member] | TOKIN [Member] | United States of America, Dollars                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party           $ 10,300                            
Competition Laws of the European Union [Member] | TOKIN [Member] | Euro Member Countries, Euro                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party | €         € 8.8                              
Competition Laws of the European Union [Member] | NEC TOKIN Corporation [Member] | United States of America, Dollars                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party           $ 5,900                            
Competition Laws of the European Union [Member] | NEC TOKIN Corporation [Member] | Euro Member Countries, Euro                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party | €         € 5.0                              
Monopoly and Fair Trade Laws [Member] | TOKIN [Member] | United States of America, Dollars | KOREA, REPUBLIC OF                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party $ 7,300                                      
Monopoly and Fair Trade Laws [Member] | TOKIN [Member] | Korea (South), Won | KOREA, REPUBLIC OF                                        
Concentration of Risk                                        
Litigation Settlement, Amount Awarded to Other Party | ₩   ₩ 8.2