Net Income per Common Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net Income per Common Share
Weighted average shares used for the basic net income per share computation	272,588,332	253,375,546	268,024,691	251,792,989
Incremental shares from share-based compensation	194,133	281,177	228,142	280,696
Weighted average shares used for diluted net income per share computation	273,099,487	253,973,745	268,569,855	252,390,707
Unvested Shares
Net Income per Common Share
Unvested shares from share-based compensation that were anti-dilutive	44,191		32,016	1,978
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	88,182	280,498	88,182	305,272