Name:	core_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedOutstandingNumber
Namespace Prefix:	core_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Share-based Compensation Arrangement by Share-based Payment Award, Total Options and Non-Options Equity Instruments, Expected to Vest, Outstanding, Aggregate Intrinsic Value

No definition available.

Name:	core_ShareBasedCompensationArrangementByShareBasedPaymentAwardTotalOptionsAndNonOptionsEquityInstrumentsExpectedToVestOutstandingAggregateIntrinsicValue
Namespace Prefix:	core_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Share-based Compensation Arrangement by Share-based Payment Award, Total Options and Non-Options Equity Instruments, Expected to Vest, Outstanding, Number

No definition available.

Name:	core_ShareBasedCompensationArrangementByShareBasedPaymentAwardTotalOptionsAndNonOptionsEquityInstrumentsExpectedToVestOutstandingNumber
Namespace Prefix:	core_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Share-based Compensation Arrangement by Share-based Payment Award, Total Options and Non-Options Equity Instruments, Vested, Outstanding, Aggregate Intrinsic Value

No definition available.

Name:	core_ShareBasedCompensationArrangementByShareBasedPaymentAwardTotalOptionsAndNonOptionsEquityInstrumentsVestedOutstandingAggregateIntrinsicValue
Namespace Prefix:	core_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Share-based Compensation Arrangement by Share-based Payment Award, Total Options and Non-Options Equity Instruments, Vested, Outstanding, Number

No definition available.

Name:	core_ShareBasedCompensationArrangementByShareBasedPaymentAwardTotalOptionsAndNonOptionsEquityInstrumentsVestedOutstandingNumber
Namespace Prefix:	core_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

No definition available.

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

Intrinsic value of equity-based compensation awards not vested. Excludes stock and unit options.

No definition available.

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

Intrinsic value of equity-based compensation awards vested. Excludes stock and unit options.

No definition available.

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsAggregateIntrinsicValueVested
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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)(i)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

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

Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Name:	us-gaap_PlanNameAxis=core_A2004LtipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PlanNameAxis=core_A2005LtipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PlanNameAxis=core_A2007LtipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: