Income Taxes - Narrative (Details) $ in Millions	Aug. 31, 2022 USD ($)
Income Tax Disclosure [Abstract]
Taxable gain recognized	$ 82.0

The taxable gain from a transaction between consolidated subsidiaries. This element refers to the gain (loss) included in taxable earnings and not consolidated earnings

No definition available.

Name:	eqc_TaxableGain
Namespace Prefix:	eqc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant