Organization, Basis of Presentation and Significant Accounting Policies (Details 2) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) community Claim home plaintiff building $ / shares shares	Mar. 31, 2017 USD ($) $ / shares shares
Basic and diluted shares outstanding
Weighted average common shares - basic (in shares) | shares	137,764,468	137,068,874
Weighted average DownREIT units outstanding (in shares) | shares	7,500	7,500
Effect of dilutive securities (in shares) | shares	381,202	454,868
Weighted average common shares - diluted (in shares) | shares	138,153,170	137,531,242
Calculation of Earnings per Share - basic
Net income attributable to common stockholders | $	$ 141,643	$ 235,875
Net income allocated to unvested restricted shares | $	(430)	(652)
Net income attributable to common stockholders, adjusted | $	$ 141,213	$ 235,223
Weighted average common shares - basic (in shares) | shares	137,764,468	137,068,874
Earnings per common share - basic (in dollars per share) | $ / shares	$ 1.03	$ 1.72
Calculation of Earnings per Share - diluted
Net income attributable to common stockholders | $	$ 141,643	$ 235,875
Add: noncontrolling interests of DownREIT unitholders in consolidated partnerships | $	11	11
Adjusted net income attributable to common stockholders | $	$ 141,654	$ 235,886
Weighted average common shares - diluted (in shares) | shares	138,153,170	137,531,242
Earnings per common share - diluted (in dollars per share) | $ / shares	$ 1.03	$ 1.72
Loss Contingencies [Line Items]
Number of operating apartment communities | community	270
Number of apartment homes included in operating apartment communities owned | home	78,388
Avalon at Edgewater
Loss Contingencies [Line Items]
Number of operating apartment communities | building	2
Number of operating apartment communities, uninhabitable | building	1
Number of units in operating apartment communities, uninhabitable | home	240
Number of apartment homes included in operating apartment communities owned | home	168
Loss contingency, new class action claims filed number	3
Loss contingency class action claims filed, number of apartments included in settlement	66
Loss Contingency Class Action Claims Filed, Number of Apartments Included in Settlement Submitted	44
Loss Contingency Class Action Claims Filed, Number of Apartments Included in Settlement Submitted Amount | $	$ 6,900
Loss Contingency Class Action Claims Filed, Number of Apartments Issued Awards By Claims Adjuster	17
Loss contingency, total class action claims filed number	4
Loss contingency, claims filed, number, consolidated	18
Loss contingency, new claims filed, number	19
Loss contingency, number of plaintiffs | plaintiff	143
Loss Contingency Class Action Claims Filed, Number of Apartments in Settlement Resolved	50
Loss Contingency Class Action Claims Filed, Number of Apartments in Settlement Previously Resolved	10
Loss Contingency Subrogation Claims Filed Pending Not Dismissed Number	1
Loss Contingency Class Action Claims Filed, Number of Apartments Included in Settlement Remaining	1
Loss contingency, new subrogation claims filed, number	7
Loss contingency, subrogation claims filed dismissed, number	1
Loss Contingency Subrogation Claims Filed Pending Not Dismissed Number	1
Loss Contingency Subrogation Claims Filed Resolved Number	1
Loss contingency, subrogation claims filed pending, number	4