Commitments and Contingent Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Irrevocable letters of credit outstanding	$ 6,092
Letters of credit outstanding as collateral for commodity hedges	3,000
Letters of credit outstanding for insurance reserve requirements of workers' compensation insurance carriers	$ 1,842

The amount of letters of credit outstanding which are required to be in compliance with workers' compensation insurance carriers reserve requirements.

No definition available.

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