Board of Trustees - Narrative (Details)	Jul. 31, 2014 trustee	May 23, 2014 trustee	Feb. 18, 2014
Board of Trustees
Minimum holders of outstanding common shares consented to the proposal, reaching the required threshold (as a percent)			66.67%
Number of trustees elected	7	7
Total number of trustees	11eqc_NumberofTrusteesInBoardofTrustees

Represents the minimum holders of outstanding common shares consented to the proposal, reaching the required threshold, expressed as a percent.

No definition available.

Name:	eqc_MinimumPercentageOfCommonStockShareholdersConsentedForTheProposalContributingRequiredThreshold
Namespace Prefix:	eqc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant