Net Income Per Common Share (Details)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Net Income Per Common Share
Weighted average shares used for the basic net income per share computation	207,003,950	171,659,191
Incremental shares from share-based compensation	3,391	151,639
Weighted average shares used for diluted net income per share computation	207,324,363	172,053,880
Unvested Shares
Net Income Per Common Share
Unvested shares from share-based compensation that were anti-dilutive	194,933	42,929
Convertible Partnership Units
Net Income Per Common Share
Weighted average partnership common units convertible to common shares that were dilutive	317,022	243,050
Unvested shares from share-based compensation that were anti-dilutive	534,546