Concentrations of Risks	9 Months Ended
Dec. 31, 2018
Risks and Uncertainties [Abstract]
Concentrations of Risks	Concentrations of Risks The Company sells to customers globally. Credit evaluations of its customers’ financial condition are performed periodically, and the Company generally does not require collateral from its customers. One of the Company's customers, TTI, Inc., an electronics distributor, accounted for over 10% of the Company’s net sales for the three and nine months ended December 31, 2018 and 2017. There were no accounts receivable balances from any customer exceeding 10% of gross accounts receivable as of December 31, 2018 and March 31, 2018. Electronics distributors are an important channel in the electronics industry and accounted for 43.4% and 38.9% of the Company's net sales for the three months ended December 31, 2018 and 2017, respectively, and 42.2% and 38.7% for the nine months ended December 31, 2018 and 2017, respectively. As a result of the Company’s concentration of sales to electronics distributors, the Company may experience fluctuations in the Company’s operating results as electronics distributors experience fluctuations in end-market demand and/or adjust their inventory stocking levels. Legal Update In July 2013, TOKIN was named as one of eight defendants in two purported U.S. class action antitrust lawsuits (In Re: Lithium Ion Batteries Antitrust Litigation, 13-MD-02420-YGR, United States District Court, Northern District of California) (the “Battery Class Action Suits”) regarding the sale of lithium ion batteries brought on behalf of direct product purchasers and indirect product purchasers. On March 2, 2018, TOKIN entered into a settlement agreement, which, subject to court approval, provides for the release of TOKIN and its subsidiaries from claims asserted in the Battery Class Action Suits, in consideration of which, TOKIN agreed to pay $2.0 million to the settlement class of indirect product purchasers. TOKIN paid the settlement amount into an escrow account on January 25, 2019. On May 16, 2018, the Court granted final approval to a settlement agreement by which, in consideration of the release of TOKIN and its subsidiaries from claims asserted in the Battery Class Action Suits, TOKIN agreed to pay $4.95 million to the settlement class of direct product purchasers. TOKIN had paid the settlement amount for the settlement class of direct product purchasers on January 18, 2018, prior to receiving the final court approval. Beginning in March 2014, TOKIN and certain of its subsidiaries received inquiries, requests for information and other communications from government authorities in China, the United States, the European Commission, Japan, South Korea, Taiwan, Singapore and Brazil concerning alleged anti-competitive activities within the capacitor industry. On September 2, 2015, the United States Department of Justice announced a plea agreement with TOKIN in which TOKIN agreed to plead guilty to a one-count felony charge of unreasonable restraint of interstate and foreign trade and commerce in violation of Section 1 of the Sherman Act, and to pay a criminal fine of $13.8 million. The plea agreement was approved by the United States District Court, Northern District of California, on January 21, 2016. The fine is payable over five years in six installments of $2.3 million each, plus accrued interest. The first four payments were made in February 2016, January 2017, January 2018, and January 2019, while the next payment is due in January 2020. On December 9, 2015, the Taiwan Fair Trade Commission (“TFTC”) publicly announced that TOKIN would be fined 1.2 billion New Taiwan dollars (“NTD”) (approximately USD $39.6 million) for violations of the Taiwan Fair Trade Act. Subsequently, the TFTC has reduced the fine to NTD 609.1 million (approximately USD $19.8 million). In February 2016, TOKIN commenced an administrative suit in Taiwan, challenging the validity of the amount of the fine. On August 23, 2018, the Taipei High Administrative Court revoked the TFTC decision, finding that the decision had been time-barred by applicable statute. On September 21, 2018, the TFTC filed an appeal against the High Administrative Court's decision. On March 29, 2016, the Japan Fair Trade Commission published an order by which TOKIN was fined JPY 127.2 million (approximately USD $1.1 million) for violation of the Japanese Antimonopoly Act. Payment of the fine was made on October 31, 2016. On July 15, 2016, TOKIN entered into definitive settlement agreements in two antitrust suits filed with the United States District Court, Northern District of California as In re: Capacitors Antitrust Litigation, No. 3:14-cv-03264-JD (the “Capacitor Class Action Suits”). Pursuant to the terms of the settlement, in consideration of the release of TOKIN and its subsidiaries (including TOKIN America, Inc.) from claims asserted in the Capacitor Class Action Suits, TOKIN will pay an aggregate $37.3 million to a settlement class of direct purchasers of capacitors and a settlement class of indirect purchasers of capacitors. Each of the respective class payments is payable in five installments, three of which have been paid on or before their respective due dates of July 29, 2016, May 15, 2017, and May 15, 2018. The fourth payment is due May 15, 2019 and the final payment is due by December 31, 2019. On July 27, 2016, Brazil’s Administrative Council for Economic Defense approved a cease and desist agreement with TOKIN in which TOKIN made a financial contribution of Brazilian Real 0.6 million (approximately USD $0.2 million) to Brazil’s Fund for Defense of Diffuse Rights. On March 21, 2018, the European Commission announced a decision by which TOKIN was fined EUR 8.8 million directly (approximately USD $10.3 million) and EUR 5.0 million (approximately USD $5.9 million) jointly and severally with NEC Corporation, for violation of the competition laws of the European Union. Payment of the fines were made on June 28, 2018. On June 4, 2018, TOKIN filed an appeal with the General Court of the European Union, seeking annulment and/or reduction of the fines. On November 30, 2018, the Korean Fair Trade Commission (“KFTC”) notified TOKIN of its decision to impose an administrative fine on TOKIN of KRW 8.1 billion (approximately USD $7.2 million) for violation of South Korea's Monopoly Regulation and Fair Trade Law. TOKIN filed its appeal of the KFTC's decision with the Seoul High Court on December 28, 2018. TOKIN is required to pay the fine by February 1, 2019, even though an appeal of the decision is currently pending. On December 6, 2018, the Ontario Superior Court of Justice approved a May 30, 2018 definitive settlement agreement with the plaintiffs in the Canadian Complaints (as defined in “Item 3. Legal Proceedings” of the Company's 2018 Form 10-K). Pursuant to the terms of the settlement, in consideration of the release of TOKIN and its subsidiaries (including TOKIN America, Inc.) from claims asserted in the Canadian Complaints, TOKIN paid CAD 2.9 million (approximately USD $2.2 million) to a settlement class of purchasers of aluminum and tantalum electrolytic capacitors and purchasers of products containing such capacitors. The settlement payment was made on June 27, 2018. On July 2, 2018, TOKIN and TOKIN America Inc. were named as two of 20 defendants in a purported U.S. class action antitrust lawsuit, In re: Inductors Antitrust Litigation, No. 5:18-cv-00198-EJD-NC, filed in the United States District Court, Northern District of California, regarding the sale of inductors brought on behalf of direct product purchasers and indirect product purchasers. The complaint alleges violations of Sections 1 and 3 of the Sherman Act, for which it seeks injunctive and equitable relief and money damages. The remaining governmental investigations are continuing at various stages. As of December 31, 2018, TOKIN’s accrual for antitrust and civil litigation claims totaled $48.2 million which is stated in the following line items, “Account payable” ($15.0 million), “Accrued expenses” ($16.7 million) and “Other non-current obligations” ($16.5 million) on the Condensed Consolidated Balance Sheets. This amount includes the best estimate of losses which may result from the ongoing antitrust investigations, civil litigation and claims. However, the actual outcomes could differ from what has been accrued. Additionally, under the terms of the TOKIN Purchase Agreement, KEMET will be responsible for defending all suits brought against TOKIN, paying all expenses and satisfying all judgments to the extent incurred by or rendered against TOKIN arising out of or related to the capacitor antitrust investigations and related litigation described above.

Concentrations of Risks

The Company sells to customers globally. Credit evaluations of its customers’ financial condition are performed periodically, and the Company generally does not require collateral from its customers. One of the Company's customers, TTI, Inc., an electronics distributor, accounted for over 10% of the Company’s net sales for the three and nine months ended December 31, 2018 and 2017. There were no accounts receivable balances from any customer exceeding 10% of gross accounts receivable as of December 31, 2018 and March 31, 2018.

Electronics distributors are an important channel in the electronics industry and accounted for 43.4% and 38.9% of the Company's net sales for the three months ended December 31, 2018 and 2017, respectively, and 42.2% and 38.7% for the nine months ended December 31, 2018 and 2017, respectively. As a result of the Company’s concentration of sales to electronics distributors, the Company may experience fluctuations in the Company’s operating results as electronics distributors experience fluctuations in end-market demand and/or adjust their inventory stocking levels.

Legal Update

In July 2013, TOKIN was named as one of eight defendants in two purported U.S. class action antitrust lawsuits (In Re: Lithium Ion Batteries Antitrust Litigation, 13-MD-02420-YGR, United States District Court, Northern District of California) (the “Battery Class Action Suits”) regarding the sale of lithium ion batteries brought on behalf of direct product purchasers and indirect product purchasers. On March 2, 2018, TOKIN entered into a settlement agreement, which, subject to court approval, provides for the release of TOKIN and its subsidiaries from claims asserted in the Battery Class Action Suits, in consideration of which, TOKIN agreed to pay $2.0 million to the settlement class of indirect product purchasers. TOKIN paid the settlement amount into an escrow account on January 25, 2019. On May 16, 2018, the Court granted final approval to a settlement agreement by which, in consideration of the release of TOKIN and its subsidiaries from claims asserted in the Battery Class Action Suits, TOKIN agreed to pay $4.95 million to the settlement class of direct product purchasers. TOKIN had paid the settlement amount for the settlement class of direct product purchasers on January 18, 2018, prior to receiving the final court approval.

Beginning in March 2014, TOKIN and certain of its subsidiaries received inquiries, requests for information and other communications from government authorities in China, the United States, the European Commission, Japan, South Korea, Taiwan, Singapore and Brazil concerning alleged anti-competitive activities within the capacitor industry.

On September 2, 2015, the United States Department of Justice announced a plea agreement with TOKIN in which TOKIN agreed to plead guilty to a one-count felony charge of unreasonable restraint of interstate and foreign trade and commerce in violation of Section 1 of the Sherman Act, and to pay a criminal fine of $13.8 million. The plea agreement was approved by the United States District Court, Northern District of California, on January 21, 2016. The fine is payable over five years in six installments of $2.3 million each, plus accrued interest. The first four payments were made in February 2016, January 2017, January 2018, and January 2019, while the next payment is due in January 2020.

On December 9, 2015, the Taiwan Fair Trade Commission (“TFTC”) publicly announced that TOKIN would be fined 1.2 billion New Taiwan dollars (“NTD”) (approximately USD $39.6 million) for violations of the Taiwan Fair Trade Act. Subsequently, the TFTC has reduced the fine to NTD 609.1 million (approximately USD $19.8 million). In February 2016, TOKIN commenced an administrative suit in Taiwan, challenging the validity of the amount of the fine. On August 23, 2018, the Taipei High Administrative Court revoked the TFTC decision, finding that the decision had been time-barred by applicable statute. On September 21, 2018, the TFTC filed an appeal against the High Administrative Court's decision.

On March 29, 2016, the Japan Fair Trade Commission published an order by which TOKIN was fined JPY 127.2 million (approximately USD $1.1 million) for violation of the Japanese Antimonopoly Act. Payment of the fine was made on October 31, 2016.

On July 15, 2016, TOKIN entered into definitive settlement agreements in two antitrust suits filed with the United States District Court, Northern District of California as In re: Capacitors Antitrust Litigation, No. 3:14-cv-03264-JD (the “Capacitor Class Action Suits”). Pursuant to the terms of the settlement, in consideration of the release of TOKIN and its subsidiaries (including TOKIN America, Inc.) from claims asserted in the Capacitor Class Action Suits, TOKIN will pay an aggregate $37.3 million to a settlement class of direct purchasers of capacitors and a settlement class of indirect purchasers of capacitors. Each of the respective class payments is payable in five installments, three of which have been paid on or before their respective due dates of July 29, 2016, May 15, 2017, and May 15, 2018. The fourth payment is due May 15, 2019 and the final payment is due by December 31, 2019.

On July 27, 2016, Brazil’s Administrative Council for Economic Defense approved a cease and desist agreement with TOKIN in which TOKIN made a financial contribution of Brazilian Real 0.6 million (approximately USD $0.2 million) to Brazil’s Fund for Defense of Diffuse Rights.

On March 21, 2018, the European Commission announced a decision by which TOKIN was fined EUR 8.8 million directly (approximately USD $10.3 million) and EUR 5.0 million (approximately USD $5.9 million) jointly and severally with NEC Corporation, for violation of the competition laws of the European Union. Payment of the fines were made on June 28, 2018. On June 4, 2018, TOKIN filed an appeal with the General Court of the European Union, seeking annulment and/or reduction of the fines.

On November 30, 2018, the Korean Fair Trade Commission (“KFTC”) notified TOKIN of its decision to impose an administrative fine on TOKIN of KRW 8.1 billion (approximately USD $7.2 million) for violation of South Korea's Monopoly Regulation and Fair Trade Law. TOKIN filed its appeal of the KFTC's decision with the Seoul High Court on December 28, 2018. TOKIN is required to pay the fine by February 1, 2019, even though an appeal of the decision is currently pending.

On December 6, 2018, the Ontario Superior Court of Justice approved a May 30, 2018 definitive settlement agreement with the plaintiffs in the Canadian Complaints (as defined in “Item 3. Legal Proceedings” of the Company's 2018 Form 10-K). Pursuant to the terms of the settlement, in consideration of the release of TOKIN and its subsidiaries (including TOKIN America, Inc.) from claims asserted in the Canadian Complaints, TOKIN paid CAD 2.9 million (approximately USD $2.2 million) to a settlement class of purchasers of aluminum and tantalum electrolytic capacitors and purchasers of products containing such capacitors. The settlement payment was made on June 27, 2018.

On July 2, 2018, TOKIN and TOKIN America Inc. were named as two of 20 defendants in a purported U.S. class action antitrust lawsuit, In re: Inductors Antitrust Litigation, No. 5:18-cv-00198-EJD-NC, filed in the United States District Court, Northern District of California, regarding the sale of inductors brought on behalf of direct product purchasers and indirect product purchasers. The complaint alleges violations of Sections 1 and 3 of the Sherman Act, for which it seeks injunctive and equitable relief and money damages.

The remaining governmental investigations are continuing at various stages. As of December 31, 2018, TOKIN’s accrual for antitrust and civil litigation claims totaled $48.2 million which is stated in the following line items, “Account payable” ($15.0 million), “Accrued expenses” ($16.7 million) and “Other non-current obligations” ($16.5 million) on the Condensed Consolidated Balance Sheets. This amount includes the best estimate of losses which may result from the ongoing antitrust investigations, civil litigation and claims. However, the actual outcomes could differ from what has been accrued. Additionally, under the terms of the TOKIN Purchase Agreement, KEMET will be responsible for defending all suits brought against TOKIN, paying all expenses and satisfying all judgments to the extent incurred by or rendered against TOKIN arising out of or related to the capacitor antitrust investigations and related litigation described above.