Annual report pursuant to Section 13 and 15(d)

Equity Method Investments - TOKIN's Joint Ventures (Details)

v3.19.1
Equity Method Investments - TOKIN's Joint Ventures (Details)
$ in Thousands
Mar. 31, 2019
USD ($)
Mar. 31, 2018
USD ($)
Apr. 19, 2017
investment
Schedule of Equity Method Investments [Line Items]      
Equity method investments $ 12,925 $ 12,016  
Nippon Yttrium Co., Ltd (NYC)      
Schedule of Equity Method Investments [Line Items]      
Ownership percentage 30.00%    
Equity method investments $ 8,215 8,148  
NT Sales Co., Ltd (NTS)      
Schedule of Equity Method Investments [Line Items]      
Ownership percentage 33.00%    
Equity method investments $ 1,218 $ 998  
KEC | TOKIN      
Schedule of Equity Method Investments [Line Items]      
Interest acquired     66.00%
Ownership percentage     100.00%
TOKIN      
Schedule of Equity Method Investments [Line Items]      
Number of investments | investment     2
TOKIN | NT Sales Co., Ltd (NTS) | Disposed of by Sale      
Schedule of Equity Method Investments [Line Items]      
Ownership percentage 67.00%