Fair Value Measurements New Convertible Notes Fair Value Assumptions and Inputs (Details) - Convertible Notes Due in 2019 [Member]	9 Months Ended
Sep. 30, 2016 $ / shares
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Share Price	$ 0.80
Fair Value Assumptions, Expected Volatility Rate	79.70%
Fair Value Inputs, Entity Credit Risk	65.75%
Fair Value Assumptions, Risk Free Interest Rate	0.91%

Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

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

- Definition

Risk-free interest rate assumption used in valuing an instrument.

+ References

+ Details

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

- Definition

Risk associated with risk of default, credit spread risk and downgrade risk, expressed as a percentage, used as an input to measure fair value.

+ References

+ Details

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

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

- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

Name:	us-gaap_SharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=cas_ConvertibleNotesDuein2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: