Net Income Per Common Share (Details) - shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net Income Per Common Share
Weighted average shares used for the basic net income per share computation	250,173,815	225,346,407
Incremental shares from share-based compensation	207,186	162,425
Weighted average shares used for diluted net income per share computation	250,698,023	225,825,854
Unvested Shares
Net Income Per Common Share
Unvested shares from share-based compensation that were anti-dilutive	400	111,338
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	330,045	440,546