Consolidated Subsidiary, Ownership Percentage

No definition available.

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

- Definition

The percentage of excess cash flow which must be used to redeem New Secured Notes due December 2018 until the Company has offered to purchase more than $100.0 million of the aggregate principal amount of the notes outstanding.

+ References

No definition available.

+ Details

Name:	cas_DebtInstrumentExcessCashFlowPercentage0Percent
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of excess cash flow which must be used to redeem New Secured Notes due December 2018 until the Company has offered to purchase up to $100.0 million of the aggregate principal amount of the notes outstanding.

+ References

No definition available.

+ Details

Name:	cas_DebtInstrumentExcessCashFlowPercentage25percent
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of excess cash flow which must be used to redeem the New Secured Notes due December 2018 until the Company has offered to purchase up to $75.0 million of the aggregate principal amount of the notes outstanding.

+ References

No definition available.

+ Details

Name:	cas_DebtInstrumentExcessCashFlowPercentage50percent
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of excess cash flow which must be used to redeem New Secured Notes due December 2018 until the Company has offered to purchase up to $50.0 million of the aggregate principal amount of the notes outstanding.

+ References

No definition available.

+ Details

Name:	cas_DebtInstrumentExcessCashFlowPercentage75percent
Namespace Prefix:	cas_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Gains and losses incurred in the period in connection with a debt restructuring.

+ References

No definition available.

+ Details

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

- Definition

The aggregate principal amount of New Senior Secured Notes due December 2018 that were received in exchange by holders of existing senior secured notes due December 2016 in a May 2016 exchange transaction.

+ References

No definition available.

+ Details

Name:	cas_NewSeniorSecuredNotesReceivedinExchangeMay2016
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Special Redemption, percent penalty applied to outstanding principle if company fails to meet special redemption provisions as defined under New Secured Notes indenture agreement.

+ References

No definition available.

+ Details

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

- 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

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:	instant

- 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:	instant

- Definition

The upper bound of the amount of New Secured Notes due December 2018 to be purchased with excess cash flow, as defined by the indenture agreement, at an excess cash flow percentage of 25%.

+ References

No definition available.

+ Details

Name:	cas_SecuredNotestobePurchasedwithExcessCashFlow100million
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The upper bound of the amount of New Secured Notes due December 2018 to be purchased with excess cash flow, as defined by the indenture agreement, at an excess cash flow percentage of 75%.

+ References

No definition available.

+ Details

Name:	cas_SecuredNotestobePurchasedwithExcessCashFlow50million
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The upper bound of the amount of New Secured Notes due December 2018 to be purchased with excess cash flow, as defined by the indenture agreement, an an excess cash flow percentage of 50%.

+ References

No definition available.

+ Details

Name:	cas_SecuredNotestobePurchasedwithExcessCashFlow75million
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The aggregate principal balance of senior secured notes due December 2016 exchanged for New Senior Secured Notes due December 2018 in a May 2016 exchange transaction.

+ References

No definition available.

+ Details

Name:	cas_SeniorNotesExchangedMay2016
Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of the aggregate principal amount of the New Secured Notes that the Company must redeem on one or more occasions prior to October 31, 2016 using cash available to the Company and/or net proceeds from sales of assets of the Company or a Restricted Subsidiary outside the normal course of business.

+ References

No definition available.

+ Details

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

- Definition

The maturity date of the New Secured Notes if the Special Redemption Condition is not met.

+ References

No definition available.

+ Details

Name:	cas_SpecialRedemptionConditionMaturityDate
Namespace Prefix:	cas_
Data Type:	xbrli:dateItemType
Balance Type:	na
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

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

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

+ Details

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

- Definition

The cash outflow for the extinguishment of long-term borrowing, with the highest claim on the assets of the entity in case of bankruptcy or liquidation, before its maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: 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=66902209&loc=d3e3291-108585

+ Details

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

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.16)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=cas_SeniorSecuredNotesDuein2018Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cas_SeniorSecuredNotesDueIn2016Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=cas_DomesticSubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
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Period Type:

Debt Secured Notes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Debt Secured Notes (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Debt Instrument [Line Items]
Senior Notes Exchanged, May 2016	$ 1,200		$ 1,200
New Senior Secured Notes, Received in Exchange, May 2016	1,200		1,200
Debt Restructuring (gains) losses, net	0	$ 0	6,562	$ 0
Senior Secured Notes Due in 2018 [Member]
Debt Instrument [Line Items]
Senior Notes	$ 204,519		$ 204,519		$ 203,319
Debt Instrument, Interest Rate, Stated Percentage	12.75%		12.75%
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			95 days
Debt Instrument, Excess Cash Flow, Percentage, 0 percent	0.00%		0.00%
Debt Instrument, Excess Cash Flow, Percentage, 25 percent	25.00%		25.00%
Debt Instrument, Excess Cash Flow, Percentage, 50 percent	50.00%		50.00%
Debt Instrument, Excess Cash Flow, Percentage, 75 percent	75.00%		75.00%
Secured Notes to be Purchased with Excess Cash Flow, 50 million	$ 50,000		$ 50,000
Secured Notes to be Purchased with Excess Cash Flow, 75 million	75,000		75,000
Secured Notes to be Purchased with Excess Cash Flow, 100 million	100,000		$ 100,000
Redemption Price, Stated as a Percentage of Principal, Percentage, Excess Cash Flow			103.00%
Debt Restructuring (gains) losses, net	$ 0		$ 7,075
Debt Instrument, Redemption Price, Percentage			100.00%
Percent, Penalty Special Redemption Provision	4.00%		4.00%
Special Redemption Condition, Maturity Date			Sep. 14, 2017
Redemption Price, Stated as a Percentage of Principal, Change of Control	101.00%		101.00%
Redemption Price, Stated as a Percentage of Principal, Upon Certain Asset Sales	100.00%		100.00%
Senior Secured Notes Due in 2016 [Member]
Debt Instrument [Line Items]
Senior Notes	$ 0		$ 0		$ 6,681
Early Repayment of Senior Debt			$ 5,629
Debt Instrument, Interest Rate, Stated Percentage	12.75%		12.75%
Domestic Subsidiaries [Member] \| Senior Secured Notes Due in 2018 [Member]
Debt Instrument [Line Items]
Consolidated Subsidiary, Ownership Percentage	100.00%		100.00%
Maximum
Debt Instrument [Line Items]
Special Redemption, Amount	$ 40,000		$ 40,000