Represents the amount of construction management fees earned from the related party during the period.

No definition available.

Name:	cor_RelatedPartyTransactionConstructionManagementFees
Namespace Prefix:	cor_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount of lease commissions earned from the related party during the period.

+ References

No definition available.

+ Details

Name:	cor_RelatedPartyTransactionLeaseCommissions
Namespace Prefix:	cor_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount of reimbursement for payroll related expenses incurred in the related party transaction.

+ References

No definition available.

+ Details

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

- Definition

Revenue, comprised of base and incentive revenue derived from the management of joint ventures, managing third-party properties, or another entity's operations.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(d))

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

+ Details

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

- Definition

Net rentable area for properties owned.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

The total amount of revenue recognized for the period from operating leases, including minimum lease revenue, contingent revenue, percentage revenue and sublease revenue.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 19

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=7501430&loc=d3e39896-112707

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

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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Related Party Transactions (Details) (USD $)	3 Months Ended	12 Months Ended		9 Months Ended	12 Months Ended
Related Party Transactions (Details) (USD $)	Dec. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Sep. 27, 2010 Predecessor	Dec. 31, 2010 CoreSite, LLC Predecessor	Dec. 31, 2012 Affiliate of the Carlyle Group VA1- Mortgage loan sqft	Dec. 31, 2011 Affiliate of the Carlyle Group VA1- Mortgage loan	Dec. 31, 2010 Affiliate of the Carlyle Group VA1- Mortgage loan
Related Party Transactions
Management fees					$ 3,600,000
Lease commissions					2,800,000
Construction management fees					1,200,000
Reimbursement for payroll related expenses					1,200,000
Net rentable space leased to an affiliate (in square feet)						1,515
Rental revenue	$ 24,428,000	$ 123,397,000	$ 108,597,000	$ 24,377,000		$ 300,000	$ 200,000	$ 200,000