Noncontrolling Interest - Common Shares and Units Activity (Details)	3 Months Ended
	Mar. 31, 2022 shares
Equity Commonwealth
Increase (Decrease) in Stockholders' Equity
Ownership percentage by noncontrolling owners	0.24%
Common Shares
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	115,205,818
Repurchase of shares (in shares)	(3,010,596)
Share-based compensation grants and vesting, net of forfeitures (in shares)	475,179
Balance as of end of period (in shares)	112,670,401
OP Units and LTIP Units | Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	247,217
Repurchase of shares (in shares)	0
Share-based compensation grants and vesting, net of forfeitures (in shares)	29,071
Balance as of end of period (in shares)	276,288
Common Stock, OP Units, and LTIP Units
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	115,453,035
Repurchase of shares (in shares)	(3,010,596)
Share-based compensation grants and vesting, net of forfeitures (in shares)	504,250
Balance as of end of period (in shares)	112,946,689