Organization, Basis of Presentation and Significant Accounting Policies (Details 2) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Basic and diluted shares outstanding
Weighted average common shares - basic (in shares)	139,291,187	140,376,996
Weighted average DownREIT units outstanding (in shares)	7,500	7,500
Effect of dilutive securities (in shares)	253,726	393,377
Weighted average common shares - diluted (in shares)	139,552,413	140,777,873
Calculation of Earnings per Share - basic
Net income attributable to common stockholders	$ 142,223	$ 167,971
Net income allocated to unvested restricted shares	(324)	(427)
Net income attributable to common stockholders, adjusted	$ 141,899	$ 167,544
Weighted average common shares - basic (in shares)	139,291,187	140,376,996
Earnings per common share - basic (in dollars per share)	$ 1.02	$ 1.19
Calculation of Earnings per Share - diluted
Net income attributable to common stockholders	$ 142,223	$ 167,971
Add: noncontrolling interests of DownREIT unitholders in consolidated partnerships	12	12
Adjusted net income attributable to common stockholders	$ 142,235	$ 167,983
Weighted average common shares - diluted (in shares)	139,552,413	140,777,873
Earnings per common share - diluted (in dollars per share)	$ 1.02	$ 1.19
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	294,115