Name:	cas_AdjustmentToAdditionalPaidInCapitalReclassificationOfConversionOptionValue
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Aggregate principal amount available for a Canadian subfacility.

No definition available.

Name:	cas_AggregatePrincipalAmountAvailableForCanadianSubfacility
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

Aggregate principal amount available for letters of credit.

No definition available.

Name:	cas_AggregatePrincipalAmountAvailableForLettersOfCredit
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Aggregate principal amount available for swingline loans.

No definition available.

Name:	cas_AggregatePrincipalAmountAvailableForSwinglineLoans
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Call of convertible notes for redemption.

No definition available.

Name:	cas_CallOfConvertibleNotesForRedemption
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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Common shares authorized for issuance at the beginning of the year.

No definition available.

Name:	cas_CommonStockSharesAuthorizedBeginningOfYear
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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Amount of outstanding principal due for the Convertible Notes at the maturity date, before deducting unamortized discount.

No definition available.

Name:	cas_ConvertibleNotesPrincipalAmount
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Convertible notes will be convertible.

No definition available.

Name:	cas_ConvertibleNotesWillBeConvertible
Namespace Prefix:	cas_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Terms of variable interest rates under the revolving credit facility.

No definition available.

Name:	cas_CustomaryBaseRatePlusApplicableMarginPercentage
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Date at which the Company may redeem some or all of the Secured Notes at a redemption premium.

No definition available.

Name:	cas_DateOfRedemption
Namespace Prefix:	cas_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	cas_DebtTextualAbstract
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Period Type:	duration

Deferred tax benefit associated with the temporary difference between the financial reporting basis of the derivative liability associated with the conversion option and its tax basis at the date of issuance.

No definition available.

Name:	cas_DeferredTaxBenefitConversionOptionValueReclassification
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Ratio of EBITDA to fixed charges required to be maintained when excess availability under the Revolving Credit Facility falls below a certain level.

No definition available.

Name:	cas_EarningsBeforeInterestTaxesDepreciationAndAmortizationToFixedChargesRatio
Namespace Prefix:	cas_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

Excess availability of revolving credit facility.

No definition available.

Name:	cas_ExcessAvailabilityOfRevolvingCreditFacility
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Holders may convert their Convertible Notes at their option.

No definition available.

Name:	cas_HoldersMayConvertTheirConvertibleNotesAtTheirOption
Namespace Prefix:	cas_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Initial conversion amount for convertible notes.

No definition available.

Name:	cas_InitialConversionAmountForConvertibleNotes
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Interest on convertible notes beginning period.

No definition available.

Name:	cas_InterestOnConvertibleNotesBeginningPeriod
Namespace Prefix:	cas_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

Issuance of shares in excess of outstanding common shares.

No definition available.

Name:	cas_IssuanceOfSharesInExcessOfOutstandingCommonShares
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Last reported sale price of common stock.

No definition available.

Name:	cas_LastReportedSalePriceOfCommonStock
Namespace Prefix:	cas_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Terms of variable interest rates under the revolving credit facility.

No definition available.

Name:	cas_LiborRate
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of the aggregate principal amount of the Secured Notes that may be redeemed before a certain specified date.

No definition available.

Name:	cas_MaximumRedemptionOfSecuredNotesPercentage
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Minimum sale price of common stock.

No definition available.

Name:	cas_MinimumSalePriceOfCommonStock
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Timeframe after the end of each fiscal year that the Company must make an offer to purchase New Secured Notes with certain of its excess cash flow for such fiscal year.

No definition available.

Name:	cas_OfferToPurchaseSecuredNotesWithCertainOfItsExcessCashFlow
Namespace Prefix:	cas_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Percentage of maximum calculated borrowing base to fixed charge of EBITDA.

No definition available.

Name:	cas_PercentageOfMaximumCalculatedBorrowingBaseToFixedChargeOfEbitda
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Percentage of senior notes redemption premium.

No definition available.

Name:	cas_PercentageOfSeniorNotesRedemptionPremium
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Redemption premium percent after certain specified date.

No definition available.

Name:	cas_PercentageOfSeniorNotesRedemptionPremiumThereafter
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Period of consecutive trading days.

No definition available.

Name:	cas_PeriodOfConsecutiveTradingDays
Namespace Prefix:	cas_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

Period of trading days.

No definition available.

Name:	cas_PeriodOfTradingDays
Namespace Prefix:	cas_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Premium that must be paid on the purchase of Secured Notes within a specified timeframe after year end.

No definition available.

Name:	cas_PrincipalAmountThereofPlusAccruedAndUnpaidInterestPercentage
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Redemption price.

No definition available.

Name:	cas_RedemptionPrice
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Redemption price percentage of principal amount.

No definition available.

Name:	cas_RedemptionPricePercentageOfPrincipalAmount
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Redemption price percentage of principal amount upon certain asset sales.

No definition available.

Name:	cas_RedemptionPricePercentageOfPrincipalAmountUponCertainAssetSales
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Secured notes redemption price percentage.

No definition available.

Name:	cas_SecuredNotesRedemptionPricePercentage
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Amount available under senior secured asset-based revolving credit facility subject to adjustment pursuant to a borrowing base calculation.

No definition available.

Name:	cas_SeniorSecuredAssetBasedRevolvingCreditFacility
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of outstanding principal due for the Senior Secured Notes at the maturity date, before deducting unamortized discount.

No definition available.

Name:	cas_SeniorSecuredNotesPrincipalAmount
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Terms of borrowing base calculation under Revolving Credit Facility as defined in agreement.

No definition available.

Name:	cas_TermsOfBorrowingBaseCalculationUnderRevolvingCreditFacility
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Trading price per note for each day of that measurement period.

No definition available.

Name:	cas_TradingPricePerNoteForEachDayOfThatMeasurementPeriod
Namespace Prefix:	cas_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

Name:	us-gaap_CommonStockSharesAuthorized
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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

The price per share of the conversion feature embedded in the debt instrument.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 20

-Section 50

-Paragraph 5

-Subparagraph (b)

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The ratio applied to the debt for purposes of determining the number of shares of the equity security into which the debt will be converted.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

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-Glossary Conversion Rate

-URI http://asc.fasb.org/extlink&oid=6509012

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

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-Section 02

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-Name Accounting Standards Codification

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-Paragraph 1

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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Interest rate stated in the contractual debt agreement.

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Period Type:	instant

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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Amount of the required periodic payments including both interest and principal payments.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

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-Name Regulation S-X (SX)

-Number 210

-Section 02

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

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-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

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

Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of debt outstanding by type or by instrument at that time.

No definition available.