Organization and Description of Business (Details) - Common Stock - Operating partnership	Jun. 30, 2015
Organization
Percentage of ownership interests held by the entity	55.50%
Percentage of ownership interests held by others	44.50%

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.

No definition available.

Name:	cor_OrganizationLineItems
Namespace Prefix:	cor_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration