Fair Value Measurements Unobservable Inputs (Details) (USD $) In Thousands, unless otherwise specified	0 Months Ended	12 Months Ended
Apr. 26, 2012	Dec. 31, 2012 Level 3 Derivative liability for conversion feature associated with convertible debt
Reconciliation of the change in fair value of Level 3 liabilities
Fair value as of January 1		$ 26,440
Mark-to-market adjustment on conversion feature		15,597
Reclassification from long-term debt to additional paid-in capital	(42,037)	(42,037)
Fair value as of December 31		$ 0

Adjustment to additional paid in capital resulting from the reclassification of the conversion option value previously recorded as debt.

No definition available.

+ Details

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Namespace Prefix:	cas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Transfers into liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

+ Details

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

- Details

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

- Definition

This element represents a liability measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

+ Details

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