Organization, Basis of Presentation and Significant Accounting Policies (Details 2) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Basic and diluted shares outstanding
Weighted average common shares - basic (in shares)	139,386,413			140,271,574			139,338,800	140,366,438
Weighted average DownREIT units outstanding (in shares)	7,500			7,500			7,500	7,500
Effect of dilutive securities (in shares)	343,812			324,648			298,769	328,865
Weighted average common shares - diluted (in shares)	139,737,725			140,603,722			139,645,069	140,702,803
Calculation of Earnings per Share - basic
Net income attributable to common stockholders	$ 78,914	$ 447,953	$ 142,223	$ 147,703	$ 170,828	$ 167,971	$ 669,090	$ 486,502
Net income allocated to unvested restricted shares	(160)			(342)			(1,443)	(1,158)
Net income attributable to common stockholders, adjusted	$ 78,754			$ 147,361			$ 667,647	$ 485,344
Weighted average common shares - basic (in shares)	139,386,413			140,271,574			139,338,800	140,366,438
Earnings per common share - basic (in dollars per share)	$ 0.57			$ 1.05			$ 4.79	$ 3.46
Calculation of Earnings per Share - diluted
Net income attributable to common stockholders	$ 78,914	$ 447,953	$ 142,223	$ 147,703	$ 170,828	$ 167,971	$ 669,090	$ 486,502
Add: noncontrolling interests of DownREIT unitholders in consolidated partnerships	12			12			36	36
Adjusted net income attributable to common stockholders	$ 78,926			$ 147,715			$ 669,126	$ 486,538
Weighted average common shares - diluted (in shares)	139,737,725			140,603,722			139,645,069	140,702,803
Earnings per common share - diluted (in dollars per share)	$ 0.56			$ 1.05			$ 4.79	$ 3.46