Second part of loan from Portuguese Government

No definition available.

Name:	kem_Secondpartofloan
Namespace Prefix:	kem_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash outflow for the payment of debt classified as other.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfOtherDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_OtherDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=kem_TOKINMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=kem_PortugueseGovernmentLoan2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Other (Details) € in Millions, ¥ in Millions, $ in Millions	1 Months Ended						3 Months Ended		66 Months Ended	96 Months Ended
	Feb. 28, 2019 USD ($)	Feb. 28, 2019 EUR (€)	Sep. 30, 2017 USD ($) Rate	Sep. 30, 2017 JPY (¥) Rate	Jul. 31, 2017 USD ($)	Jul. 31, 2017 EUR (€)	Mar. 31, 2018 USD ($)	Mar. 31, 2018 EUR (€)	Sep. 01, 2026 USD ($)	Feb. 01, 2025 USD ($)	Feb. 01, 2025 EUR (€)
Debt Instrument [Line Items]
Second part of loan					$ 0.3	€ 0.3
Other Debt Obligations
Debt Instrument [Line Items]
Proceeds from issuance of debt							$ 2.5	€ 2.2
Other Debt Obligations \| TOKIN
Debt Instrument [Line Items]
Proceeds from issuance of debt			$ 3.2	¥ 350
Debt Instrument, Basis Spread on Variable Rate			0.40%	0.40%
Stated interest rate (as a percent)			0.53%	0.53%
Other Debt Obligations \| Forecast
Debt Instrument [Line Items]
Repayments of other debt										$ 0.2	€ 0.2
Portuguese Government Loan 2 \| Other Debt Obligations
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 1.1	€ 0.9
Portuguese Government Loan 2 \| Other Debt Obligations \| Forecast
Debt Instrument [Line Items]
Repayments of other debt \| $									$ 0.1