Net Income per Common Share (Details) - shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Net Income per Common Share
Weighted average shares used for the basic net income per share computation	263,340,491	250,173,815
Incremental shares from share-based compensation	276,791	207,186
Weighted average shares used for diluted net income per share computation	263,934,304	250,698,023
Unvested Shares
Net Income per Common Share
Unvested shares from share-based compensation that were anti-dilutive	58,887	400
Convertible Partnership Units
Net Income per Common Share
Weighted average partnership common units convertible to common shares that were dilutive	317,022	317,022
Unvested shares from share-based compensation that were anti-dilutive	88,182	330,045