Organization, Basis of Presentation and Significant Accounting Policies (Details 2) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Basic and diluted shares outstanding
Weighted average common shares - basic (in shares)	140,271,574			139,340,142			140,366,438	138,931,955
Weighted average DownREIT units outstanding (in shares)	7,500			7,500			7,500	7,500
Effect of dilutive securities (in shares)	324,648			505,032			328,865	498,609
Weighted average common shares - diluted (in shares)	140,603,722			139,852,674			140,702,803	139,438,064
Calculation of Earnings per Share - basic
Net income attributable to common stockholders	$ 147,703	$ 170,828	$ 167,971	$ 279,677	$ 168,281	$ 170,366	$ 486,502	$ 618,324
Net income allocated to unvested restricted shares	(342)			(704)			(1,158)	(1,655)
Net income attributable to common stockholders, adjusted	$ 147,361			$ 278,973			$ 485,344	$ 616,669
Weighted average common shares - basic (in shares)	140,271,574			139,340,142			140,366,438	138,931,955
Earnings per common share - basic (in dollars per share)	$ 1.05			$ 2.00			$ 3.46	$ 4.44
Calculation of Earnings per Share - diluted
Net income attributable to common stockholders	$ 147,703	$ 170,828	$ 167,971	$ 279,677	$ 168,281	$ 170,366	$ 486,502	$ 618,324
Add: noncontrolling interests of DownREIT unitholders in consolidated partnerships	12			11			36	34
Adjusted net income attributable to common stockholders	$ 147,715			$ 279,688			$ 486,538	$ 618,358
Weighted average common shares - diluted (in shares)	140,603,722			139,852,674			140,702,803	139,438,064
Earnings per common share - diluted (in dollars per share)	$ 1.05			$ 2.00			$ 3.46	$ 4.43