Noncontrolling Interest - Common Shares and Units Activity (Details)	9 Months Ended
Sep. 30, 2018 shares
Increase (Decrease) in Stockholders' Equity
Ownership percentage by noncontrolling owners	0.04%
Common Shares
Increase (Decrease) in Stockholders' Equity
Outstanding, beginning balance (in shares)	124,217,616
Repurchase of shares (in shares)	(2,970,209)
Restricted share, time-based LTIP Unit grants and vested restricted stock units, net of forfeitures (in shares)	235,266
Outstanding, ending balance (in shares)	121,482,673
OP Units and LTIP Units \| Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Outstanding, beginning balance (in shares)	42,520
Repurchase 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
Common Stock, LTIP Units, and OP Units
Increase (Decrease) in Stockholders' Equity
Outstanding, beginning balance (in shares)	124,260,136
Repurchase of shares (in shares)	(2,970,209)
Restricted share, time-based LTIP Unit grants and vested restricted stock units, net of forfeitures (in shares)	238,466
Outstanding, ending balance (in shares)	121,528,393

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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