Concentrations of Risks (Details) $ in Thousands, € in Millions, ¥ in Millions, R$ in Millions, $ in Millions, $ in Millions, ₩ in Billions																	3 Months Ended		9 Months Ended
		Nov. 30, 2018 USD ($)	Nov. 30, 2018 KRW (₩)	Jun. 27, 2018 USD ($)	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 ($) installment	Jul. 31, 2013 defendant suit	Dec. 31, 2018 USD ($)	Dec. 31, 2017	Dec. 31, 2018 USD ($)	Dec. 31, 2017	Mar. 31, 2018 USD ($)
Concentration of Risk
Accounts Payable, Trade, Current																	$ 144,418		$ 144,418		$ 139,989
Accrued expenses	[1]																98,279		98,279		125,119
Other non-current obligations	[1]																$ 125,856		$ 125,856		$ 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																			42.20%	38.70%
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																	43.40%	38.90%
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													$ 39,600
United States of America, Dollars | TAIWAN, PROVINCE OF CHINA | Minimum [Member]
Concentration of Risk
Loss Contingency, Damages Sought, Value													$ 19,800
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																	$ 48,200		$ 48,200
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																	15,000		15,000
Accrued expenses																	16,700		16,700
Other non-current obligations																	16,500		$ 16,500
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		$ 7,200
Monopoly and Fair Trade Laws [Member] | TOKIN [Member] | Korea (South), Won | KOREA, REPUBLIC OF
Concentration of Risk
Litigation Settlement, Amount Awarded to Other Party | ₩			₩ 8.1

[1] Period ended March 31, 2018 adjusted due to the adoption of Accounting Standard Codification (“ASC”) 606, Revenue from Contracts with Customers (“ASC 606”). Refer to Note 1, “Basis of Financial Statement Presentation.”