Performance Share Status (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized \| $	$ 1,659
Long-Term Compensation Plan - 2014 [Member] \| Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
PSU Target Goal Performance Period	3 years
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized \| $	$ 0
Long-Term Compensation Plan - 2014 [Member] \| Non-Market-Based Performance Condition One
Summary of award information associated with market and non-market-based performance condition awards
Grant Date Fair Value \| $ / shares	$ 14.35
Estimated Number of Performance Shares to be Issued \| shares	0
Long-Term Compensation Plan - 2014 [Member] \| Market Based Performance Share Units [Member]
Summary of award information associated with market and non-market-based performance condition awards
Grant Date Fair Value \| $ / shares	$ 20.16
Estimated Number of Performance Shares to be Issued \| shares	0

Long-Term Compensation Plan, PSU Performance Period

No definition available.

Name:	casl_LongTermCompensationPlanPSUPerformancePeriod
Namespace Prefix:	casl_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Performance-based awards estimated to be issued at the end of the performance period.

+ References

No definition available.

+ Details

Name:	casl_ShareBasedCompensationArrangementsPerformanceBasedAwardsSharesEstimatedToBeIssued
Namespace Prefix:	casl_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=casl_LongTermCompensationPlan2014Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=casl_NonMarketBasedPerformanceShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=casl_MarketBasedPerformanceShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: