Net Income Per Common Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Net Income Per Common Share
Weighted average shares used for the basic net income per share computation	258,085,633	236,211,706	253,953,149	231,434,521
Incremental shares from share-based compensation	271,259	211,214	270,152	111,224
Weighted average shares used for diluted net income per share computation	258,673,914	236,739,942	254,540,323	231,862,767
Unvested Shares
Net Income Per Common Share
Unvested shares from share-based compensation that were anti-dilutive	224	132,948	231	107,879
Convertible Partnership Units
Net Income Per Common Share
Weighted average partnership common units convertible to common shares that were dilutive	317,022	317,022	317,022	317,022
Unvested shares from share-based compensation that were anti-dilutive	97,312	419,546	235,446	426,469