Noncontrolling Interest - Common Shares and Units Activity (Details)	12 Months Ended
	Dec. 31, 2017 shares
Increase (Decrease) in Stockholders' Equity
Ownership percentage by noncontrolling owners	0.03%
Common Shares
Increase (Decrease) in Stockholders' Equity
Outstanding, beginning balance (in shares)	123,994,465
Restricted share and time-based LTIP Unit grants, net of forfeitures (in shares)	223,151
Outstanding, ending balance (in shares)	124,217,616
LTIP units | Noncontrolling Interest
Increase (Decrease) in Stockholders' Equity
Outstanding, beginning balance (in shares)	0
Restricted share and time-based LTIP Unit grants, net of forfeitures (in shares)	42,520
Outstanding, ending balance (in shares)	42,520
Common Shares and LTIP Units
Increase (Decrease) in Stockholders' Equity
Outstanding, beginning balance (in shares)	123,994,465
Restricted share and time-based LTIP Unit grants, net of forfeitures (in shares)	265,671
Outstanding, ending balance (in shares)	124,260,136