Noncontrolling Interest - Common Shares and Units Activity (Details)	3 Months Ended
	Mar. 31, 2023 shares
Equity Commonwealth
Increase (Decrease) in Stockholders' Equity
Noncontrolling ownership interest in the Operating Trust	0.32%
Common Shares
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	109,428,252
Repurchase and surrender of shares (in shares)	(134,193)
Share-based compensation grants and vesting, net of forfeitures (in shares)	407,533
Balance as of end of period (in shares)	109,701,592
OP Units and LTIP Units | Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	279,892
Repurchase and surrender of shares (in shares)	0
Share-based compensation grants and vesting, net of forfeitures (in shares)	75,745
Balance as of end of period (in shares)	355,637
Common Stock, OP Units, and LTIP Units
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	109,708,144
Repurchase and surrender of shares (in shares)	(134,193)
Share-based compensation grants and vesting, net of forfeitures (in shares)	483,278
Balance as of end of period (in shares)	110,057,229