Noncontrolling Interest - Common Shares and Units Activity (Details)	9 Months Ended
Sep. 30, 2022 shares
Equity Commonwealth
Increase (Decrease) in Stockholders' Equity
Noncontrolling ownership interest in the Operating Trust	0.25%
Common Shares
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	115,205,818
Repurchase and surrender of shares (in shares)	(5,047,833)
Share-based compensation grants and vesting, net of forfeitures (in shares)	493,586
Balance as of end of period (in shares)	110,651,571
OP Units and LTIP Units \| Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	247,217
Repurchase and surrender of shares (in shares)	0
Share-based compensation grants and vesting, net of forfeitures (in shares)	32,675
Balance as of end of period (in shares)	279,892
Common Stock, OP Units, and LTIP Units
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	115,453,035
Repurchase and surrender of shares (in shares)	(5,047,833)
Share-based compensation grants and vesting, net of forfeitures (in shares)	526,261
Balance as of end of period (in shares)	110,931,463

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Number of shares issued which are neither cancelled nor held in the treasury.

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Number, after forfeiture, of shares or units issued under share-based payment arrangement. Excludes shares or units issued under employee stock ownership plan (ESOP).

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Number of shares that have been repurchased and retired during the period.

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