Commitments and Contingencies.

No definition available.

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- Definition

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments that has been fulfilled..

+ References

No definition available.

+ Details

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Namespace Prefix:	cor_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

+ References

No definition available.

+ Details

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

- Definition

Amount awarded to other party in judgment or settlement of litigation.

+ References

No definition available.

+ Details

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

- Definition

The value (monetary amount) of the award the plaintiff seeks in the legal matter.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

+ Details

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

- Definition

Minimum amount of other commitment maturing in the next fiscal year following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

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

- Details

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- Details

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- Details

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- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=cor_DamagesRelatedToServicesRenderedMember
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- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=cor_DamagesForLossOfRevenueAndOtherCostsMember
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Commitments and Contingencies (Details) - USD ($)			12 Months Ended
Commitments and Contingencies (Details) - USD ($)	Mar. 02, 2018	Jul. 23, 2015	Dec. 31, 2018	Mar. 31, 2018
Telecommunications Capacity
Commitments and Contingencies
Open commitments				$ 100,100,000
Telecommunications Capacity \| Forecast
Commitments and Contingencies
Open commitments met			$ 2,000,000
Construction Contracts
Commitments and Contingencies
Open commitments				$ 107,600,000
Damages Related To Services Rendered
Commitments and Contingencies
Loss Contingency, Damages Sought		$ 802,564
Damages For Alleged Loss Of Revenue And Other Costs
Commitments and Contingencies
Loss Contingency, Damages Sought		$ 70,080,000
Purchase price	$ 8,600,000
Settlement amount	$ 2,300,000