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

No definition available.

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

- Definition

As of the balance sheet date, the amount of excess cash flow, as defined by the indenture agreement, required to be offered for the purpose of purchasing outstanding Senior Secured Notes

+ References

No definition available.

+ Details

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

- Definition

Redemption Price, Stated as a Percentage of Principal

+ References

No definition available.

+ Details

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

- Definition

Redemption Price, Stated as a Percentage of Principal, Change of Control

+ References

No definition available.

+ Details

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

- Definition

Redemption Price, Stated as a Percentage of Principal, Upon Certain Asset Sales

+ References

No definition available.

+ Details

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

- Definition

The amount of the redemption price in percentage in the event of excess cash flow.

+ References

No definition available.

+ Details

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

- Definition

The amount of Senior Secured Notes purchased with excess cash flow, as defined by the indenture agreement

+ References

No definition available.

+ Details

Name:	cas_SecuredNotesPurchasedwithExcessCashFlow
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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. Days After Fiscal Year End

+ References

No definition available.

+ Details

Name:	cas_TimeframeAfterEndOfEachFiscalYearThatCompanyMustMakeOfferToPurchaseNewSecuredNotesWithCertainOfItsExcessCashFlowForSuchFiscalYearDaysAfterFiscalYearEnd
Namespace Prefix:	cas_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ Details

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

- Definition

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

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: 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

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

- Details

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

- Definition

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

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: 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)(2))

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

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

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

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12317-112629

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 470

-SubTopic 50

-Section 40

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6850294&loc=d3e12355-112629

+ Details

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

- Definition

The amount of cash paid for interest during the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

+ Details

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

- Details

Name:	cas_RedemptionDateAxis=cas_RedemptionDateRange121514121415Member
Namespace Prefix:
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Period Type:

- Details

Name:	cas_RedemptionDateAxis=cas_RedemptionDateRangeafter121415Member
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cas_SeniorSecuredNotesDueIn2016Member
Namespace Prefix:
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Period Type:

Debt Secured Notes (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 12, 2012	Dec. 15, 2011
Debt Instrument [Line Items]
Interest Paid			$ 32,278us-gaap_InterestPaid	$ 33,266us-gaap_InterestPaid	$ 34,051us-gaap_InterestPaid
Gains (Losses) on Extinguishment of Debt			0	(2,606)	0
Senior Secured Notes Due in 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						225,000	225,000
Stated interest rate on debt			12.75%			12.75%	12.75%
Interest Paid			26,775	28,548	28,688
Maturity date			Dec. 15, 2016
Date of redemption			On or after December 15, 2014
Redemption price stated as a percentage of principal			101.00%
Redemption price on principal amount, percentage, upon certain asset sales			100.00%
Offer to purchase secured notes with certain of its excess cash flow			95 days
Requirement to purchase secured notes with excess cash flows as a percentage of outstanding principal			103.00%
Excess Cash Flow Per Senior Secured Note Agreement	0		0	0	17,000
Secured Notes Purchased with Excess Cash Flow		0
Extinguishment of Debt, Amount	15,000
Gains (Losses) on Extinguishment of Debt				$ (2,606)
Redemption Date Range 12/15/14 - 12/14/15 [Member] \| Senior Secured Notes Due in 2016 [Member]
Debt Instrument [Line Items]
Redemption percentage after disclosed date			106.375%
Redemption Date Range after 12/14/15 [Member] \| Senior Secured Notes Due in 2016 [Member]
Debt Instrument [Line Items]
Redemption percentage after disclosed date			100.00%