Noncontrolling Interest - Common Shares and Units Activity (Details)	3 Months Ended
Mar. 31, 2020 shares
Equity Commonwealth
Increase (Decrease) in Stockholders' Equity
Ownership percentage by noncontrolling owners	0.19%
Common Shares
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	121,924,199
Repurchase of shares (in shares)	(894,466)
Restricted share, time-based LTIP Unit grants and vested restricted stock units, net of forfeitures (in shares)	472,787
Balance as of end of period (in shares)	121,502,520
OP Units and LTIP Units \| Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	48,660
Repurchase of shares (in shares)	0
Restricted share, time-based LTIP Unit grants and vested restricted stock units, net of forfeitures (in shares)	186,304
Balance as of end of period (in shares)	234,964
Common Stock, OP Units, and LTIP Units
Increase (Decrease) in Stockholders' Equity
Balance as of beginning of period (in shares)	121,972,859
Repurchase of shares (in shares)	(894,466)
Restricted share, time-based LTIP Unit grants and vested restricted stock units, net of forfeitures (in shares)	659,091
Balance as of end of period (in shares)	121,737,484

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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