Noncontrolling Interest - Common Shares and Units Activity (Details)	12 Months Ended
Dec. 31, 2018 shares
Increase (Decrease) in Stockholders' Equity
Ownership percentage by noncontrolling owners	0.04%
Common Shares, OP Units and LTIP Units
Increase (Decrease) in Stockholders' Equity
Outstanding, beginning balance (in shares)	124,260,136
Redemption of shares (in shares)	(2,970,209)
Restricted share, time-based LTIP Unit grants and vested restricted stock units, net of forfeitures (in shares)	327,948
Outstanding, ending balance (in shares)	121,617,875
Common Shares
Increase (Decrease) in Stockholders' Equity
Outstanding, beginning balance (in shares)	124,217,616
Redemption of shares (in shares)	(2,970,209)
Restricted share, time-based LTIP Unit grants and vested restricted stock units, net of forfeitures (in shares)	324,748
Outstanding, ending balance (in shares)	121,572,155
OP Units and LTIP Units \| Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Outstanding, beginning balance (in shares)	42,520
Redemption of shares (in shares)	0
Restricted share, time-based LTIP Unit grants and vested restricted stock units, net of forfeitures (in shares)	3,200
Outstanding, ending balance (in shares)	45,720

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 of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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

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