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

Board of Trustees - Narrative (Details) - trustee	Jun. 16, 2015	Jul. 31, 2014	May. 23, 2014	Feb. 18, 2014
Board of Trustees
Number of trustees elected		7	7
Total number of trustees	11	11
Minimum holders of outstanding common shares consented to the proposal, reaching the required threshold (as a percent)				66.67%