Represents the working capital adjustment associated with the acquisition of the acquired entity.

No definition available.

Name:	kem_BusinessAcquisitionCostOfAcquiredEntityWorkingCapitalAdjustment
Namespace Prefix:	kem_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Combination, Indemnity Asset

+ References

No definition available.

+ Details

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Namespace Prefix:	kem_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Deferred Income Tax Liability

+ References

No definition available.

+ Details

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

- Definition

Business Combination, Put Option Liability

+ References

No definition available.

+ Details

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Namespace Prefix:	kem_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Accrued Expenses

+ References

No definition available.

+ Details

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Namespace Prefix:	kem_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Equity Method Investment

+ References

No definition available.

+ Details

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Namespace Prefix:	kem_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the number of manufacturing sites operated by the entity.

+ References

No definition available.

+ Details

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Namespace Prefix:	kem_
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Balance Type:	na
Period Type:	instant

- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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Period Type:	duration

- Definition

Amount of direct costs of the business combination including legal, accounting, and other costs incurred to consummate the business acquisition.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

Percentage of voting equity interests acquired at the acquisition date in the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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- Definition

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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- Definition

The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

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- Definition

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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

- Definition

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

+ References

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-Paragraph 2
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Balance Type:	credit
Period Type:	duration

- Definition

In a business combination in which the amount of net identifiable assets acquired and liabilities assumed exceeds the aggregate consideration transferred or to be transferred (as defined), this element represents the amount of gain recognized by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-SubTopic 30
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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Balance Type:	credit
Period Type:	duration

- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

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-Paragraph 6
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

For indemnification assets recognized in connection with a business combination, this element represents an estimate of the low-end of the potential range (undiscounted) of the indemnification benefit which may be realized.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	credit
Period Type:	instant

- Definition

This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to equity interests acquired in connection with a business combination for which the initial accounting was incomplete.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Paragraph 4A
-Subparagraph (c)
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to intangibles acquired in connection with a business combination for which the initial accounting was incomplete.

+ References

+ Details

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

- Definition

This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to property, plant, and equipment acquired in connection with a business combination for which the initial accounting was incomplete.

+ References

+ Details

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

- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of other assets expected to be realized or consumed before one year or the normal operating cycle, if longer, acquired at the acquisition date.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount due from customers or clients for goods or services, including trade receivables, that have been delivered or sold in the normal course of business, and amounts due from others, including related parties expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer, acquired at the acquisition date.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of liabilities incurred for goods and services received that are used in an entity's business and related party payables, assumed at the acquisition date.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of deferred tax liability attributable to taxable temporary differences assumed at the acquisition date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=75116654&loc=d3e31917-109318

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-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=73530397&loc=d3e4845-128472

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of inventory recognized as of the acquisition date.

+ References

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-Name Accounting Standards Codification
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-SubTopic 20
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-Paragraph 37
-URI http://asc.fasb.org/extlink&oid=73531372&loc=d3e2207-128464

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of other assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date.

+ References

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Namespace Prefix:	us-gaap_
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Period Type:	instant

- Definition

The amount of property, plant, and equipment recognized as of the acquisition date.

+ References

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Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	instant

- Definition

Fair value at acquisition-date of the equity interest in the acquiree held by the acquirer, immediately before the acquisition date for businesses combined in stages.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

In a business combination achieved in stages, this element represents the amount of net gain (loss) recognized by the entity as a result of remeasuring to fair value the equity interest in the acquiree it held before the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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Balance Type:	na
Period Type:	instant

- Definition

Fair value of financial instrument classified as derivative asset (liability) after deduction of derivative liability (asset), measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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Namespace Prefix:	us-gaap_
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Period Type:	instant

- Definition

The fair value of assets acquired in noncash investing or financing activities.

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Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	duration

- Definition

Foreign exchange rate used to translate amounts denominated in functional currency to reporting currency.

+ References

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	instant

- Definition

This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. This item includes income or expense related to stock-based compensation based on the investor's grant of stock to employees of an equity method investee.

+ References

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Acquisitions (Details) $ / shares in Units, shares in Thousands, $ in Thousands, ¥ in Billions			1 Months Ended	3 Months Ended		9 Months Ended
	Apr. 19, 2017 USD ($) Rate	Apr. 19, 2017 JPY (¥)	Apr. 19, 2017 USD ($) Rate	Dec. 31, 2017 USD ($) manufacturing_site $ / shares Rate shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) manufacturing_site $ / shares Rate shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2017 JPY (¥) manufacturing_site Rate	Apr. 19, 2017 JPY (¥) Rate	Apr. 14, 2017 USD ($)	Apr. 14, 2017 JPY (¥)	Mar. 31, 2017 USD ($) Rate
Business Acquisition [Line Items]
Foreign Currency Exchange Rate, Translation \| Rate	10900.70%		10900.70%	11250.20%		11250.20%		11250.20%	10900.70%			11182.30%
Fair Value of Assets Acquired	$ (422,933)
Pro forma revenues				$ 306,408	$ 263,260	$ 899,353	$ 785,388
Pro forma net income (loss) from continuing operations available to common stockholders				$ 19,009	$ (4,484)	$ 44,741	$ 243,746
Pro forma earnings per common share - basic \| $ / shares				$ 0.33	$ (0.10)	$ 0.87	$ 5.25
Pro forma earnings per common share - diluted \| $ / shares				$ 0.32	$ (0.10)	$ 0.77	$ 4.51
Pro forma common shares - basic \| shares				56,778	46,606	51,340	46,469
Pro forma common shares - diluted \| shares				58,937	55,296	58,431	46,469
Equity income (loss) from equity method investments			$ 75,417	$ 238	$ (133)	$ 75,879	$ 271
Business Combination, Bargain Purchase, Gain Recognized, Amount				(310)	0	(137,183)	$ 0
Business Acquisition Cost of Acquired Entity Working Capital Adjustment				0		0		¥ 0.3
Goodwill, Purchase Accounting Adjustments				4,600
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Equity Interests				1,700
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles				(300)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Deferred Income Tax Liability				6,900
TOKIN [Member]
Business Acquisition [Line Items]
Cash	315,743		315,743
Accounts Receivable	79,295		79,295
Inventory	35,310		35,310
Other current assets	20,902		20,902
Property, Plant and equipment (1)	154,961		154,961
Intangible assets	33,025		33,025
Equity method investments (1)	11,128		11,128
Other assets	8,617		8,617
Current portion of long term debt	(3,225)		(3,225)
Accounts payable	(81,642)		(81,642)
Accrued expenses	(46,276)		(46,276)
Other non-current obligations	(103,486)		(103,486)
Deferred income taxes (1)	(1,419)		(1,419)
Total net assets acquired	$ 422,933		$ 422,933
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years	10 years
Business Acquisition, Transaction Costs				$ 800		800
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net					68,500	$ 70,600
Business Combination, Bargain Purchase, Gain Recognized, Amount	$ (66,623)				$ (64,600)
KEC [Member] \| TOKIN [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage	100.00%		100.00%						100.00%
Business Acquisition, Percentage of Voting Interests Acquired	66.00%		66.00%						66.00%
Payments to Acquire Businesses, Gross	$ 148,600	¥ 16.2
TOKIN [Member]
Business Acquisition [Line Items]
Number of Manufacturing Sites \| manufacturing_site				6		6		6
Disposal Group, Including Discontinued Operation, Consideration									¥ 10.2	$ 431,000	¥ 48.2
Business Combination, Consideration Transferred	150,358
TOKIN [Member] \| Cash Distribution [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	148,614
TOKIN [Member] \| Acquisition-related Costs [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability	3,144		$ 3,144
TOKIN [Member] \| Other Assets [Member]
Business Acquisition [Line Items]
Indemnity asset	8,500		8,500
TOKIN [Member] \| Put Option [Member]
Business Acquisition [Line Items]
Less: Put option	(9,900)		(9,900)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	(9,900)		(9,900)
Fair Value, Measurements, Recurring [Member]
Business Acquisition [Line Items]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs				$ 0		$ 0						$ (9,900)
NEC TOKIN Corporation [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage				34.00%	34.00%	34.00%	34.00%	34.00%
Equity income (loss) from equity method investments							$ 271
TOKIN [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage					34.00%		34.00%
Equity income (loss) from equity method investments			$ 75,177	$ 123,400	$ (133)
Stock Purchase Agreement [Member] \| NEC TOKIN Corporation [Member] \| KEMET Electronics Corporation [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage				34.00%	34.00%	34.00%	34.00%	34.00%
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value	205,952
Pro Forma [Member]
Business Acquisition [Line Items]
Pro forma common shares - diluted \| shares							53,990
Equity Method Investments [Member] \| Stockholders Agreement [Member]
Business Acquisition [Line Items]
Business Combination, Indemnification Assets, Amount as of Acquisition Date				$ 25,000		$ 25,000
Products and relationships \| TOKIN [Member]
Business Acquisition [Line Items]
Intangible assets				25,000		25,000
Excess cash [Member] \| KEC [Member] \| TOKIN [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	93,600	10.2
Cash Distribution [Member] \| KEC [Member] \| TOKIN [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 55,000	¥ 6.0
Trade Names [Member] \| TOKIN [Member]
Business Acquisition [Line Items]
Intangible assets				$ 8,000		$ 8,000