Consolidated Statement Of Shareholders' Equity - USD ($) $ in Thousands	Total	downREIT OP units	5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 392,878 shares issued and outstanding	Preferred Shares	Preferred Shares 5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 392,878 shares issued and outstanding	Common Shares	Common Shares downREIT OP units	Common Shares 5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 392,878 shares issued and outstanding	Additional Paid-in Capital	Additional Paid-in Capital downREIT OP units	Additional Paid-in Capital 5.417% Series 1 Cumulative Convertible Preferred Shares, (stated at liquidation preference $25 per share), 392,878 shares issued and outstanding	Accumulated Dividends in Excess of Net Income	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interest	Noncontrolling Interest downREIT OP units
Beginning balance (in shares) at Dec. 31, 2021				405,896		78,603,305
Beginning balance at Dec. 31, 2021	$ 2,663,148			$ 159,997		$ 790			$ 3,488,794			$ (1,066,932)	$ (2,047)	$ 82,546
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding amounts attributable to redeemable noncontrolling interests	115,668											113,660		2,008
Other comprehensive income (loss) - change in fair value of interest rate swaps, excluding portion attributable to redeemable noncontrolling interests	5,597												5,597
Dividends declared to common shareholders	(169,173)											(169,173)
Dividends declared to preferred shareholders	(4,018)											(4,018)
Distributions declared to noncontrolling interests, excluding amounts attributable to redeemable noncontrolling interests	(2,625)													(2,625)
Common shares issued, net (in shares)						2,203,697
Common shares issued, net	259,452					$ 22			259,430
Shares issued under dividend reinvestment plan (in shares)						8,000
Shares issued under dividend reinvestment plan	1,011								1,011
Share-based compensation expense, net of forfeitures (in shares)						104,105
Share-based compensation expense, net of forfeitures	7,679					$ 1			7,678
Shares withheld for employee taxes (in shares)						(38,576)
Shares withheld for employee taxes	(4,638)								(4,638)
Conversion of preferred shares (in shares)					(7,018)
Conversion of preferred shares					$ (175)
Conversion of preferred shares (in shares)								1,675
Conversion of preferred shares			$ 0								$ 175
Conversion and redemption of downREIT OP units (in Shares)							14,598
Conversion and redemption of downREIT OP units		$ 0					$ 0			$ 1,385
Conversion and redemption of downREIT OP units															$ (1,385)
Adjustment to redeemable noncontrolling interests	4,326								4,326
Ending balance (in shares) at Jun. 30, 2022				398,878		80,896,804
Ending balance at Jun. 30, 2022	2,876,427			$ 159,822		$ 813			3,758,161			(1,126,463)	3,550	80,544
Beginning balance (in shares) at Mar. 31, 2022				405,896		79,417,472
Beginning balance at Mar. 31, 2022	2,714,577			$ 159,997		$ 799			3,572,591			(1,101,154)	1,525	80,819
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding amounts attributable to redeemable noncontrolling interests	62,675											61,676		999
Other comprehensive income (loss) - change in fair value of interest rate swaps, excluding portion attributable to redeemable noncontrolling interests	2,025												2,025
Dividends declared to common shareholders	(84,977)											(84,977)
Dividends declared to preferred shareholders	(2,008)											(2,008)
Distributions declared to noncontrolling interests, excluding amounts attributable to redeemable noncontrolling interests	(866)													(866)
Common shares issued, net (in shares)						1,473,928
Common shares issued, net	176,703					$ 14			176,689
Shares issued under dividend reinvestment plan (in shares)						4,230
Shares issued under dividend reinvestment plan	509								509
Share-based compensation expense, net of forfeitures (in shares)						(4,786)
Share-based compensation expense, net of forfeitures	3,500					$ 0			3,500
Shares withheld for employee taxes (in shares)						(306)
Shares withheld for employee taxes	(37)								(37)
Conversion of preferred shares (in shares)					(7,018)
Conversion of preferred shares					$ (175)
Conversion of preferred shares (in shares)								1,675
Conversion of preferred shares			$ 0								$ 175
Conversion and redemption of downREIT OP units (in Shares)							4,591
Conversion and redemption of downREIT OP units		0					$ 0			408
Conversion and redemption of downREIT OP units															(408)
Adjustment to redeemable noncontrolling interests	4,326								4,326
Ending balance (in shares) at Jun. 30, 2022				398,878		80,896,804
Ending balance at Jun. 30, 2022	2,876,427			$ 159,822		$ 813			3,758,161			(1,126,463)	3,550	80,544
Beginning balance (in shares) at Dec. 31, 2022				398,878		81,342,959
Beginning balance at Dec. 31, 2022	3,034,015			$ 159,822		$ 818			3,821,801			(1,034,186)	5,757	80,003
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding amounts attributable to redeemable noncontrolling interests	117,516											115,834		1,682
Other comprehensive income (loss) - change in fair value of interest rate swaps, excluding portion attributable to redeemable noncontrolling interests	(261)												(261)
Dividends declared to common shareholders	(176,064)											(176,064)
Dividends declared to preferred shareholders	(4,016)											(4,016)
Distributions declared to noncontrolling interests, excluding amounts attributable to redeemable noncontrolling interests	(2,202)													(2,202)
Common shares issued, net (in shares)						57,096
Common shares issued, net	6,192					$ 1			6,191
Shares issued under dividend reinvestment plan (in shares)						9,631
Shares issued under dividend reinvestment plan	905								905
Share-based compensation expense, net of forfeitures (in shares)						141,234
Share-based compensation expense, net of forfeitures	8,130					$ 1			8,129
Shares withheld for employee taxes (in shares)						(42,932)
Shares withheld for employee taxes	(4,711)								(4,711)
Conversion and redemption of downREIT OP units (in Shares)							7,523
Conversion and redemption of downREIT OP units		$ 0					$ 0			$ 668
Conversion and redemption of downREIT OP units															$ (668)
Contributions from noncontrolling interests	927													927
Ending balance (in shares) at Jun. 30, 2023				398,878		81,515,511
Ending balance at Jun. 30, 2023	2,980,431			$ 159,822		$ 820			3,832,983			(1,098,432)	5,496	79,742
Beginning balance (in shares) at Mar. 31, 2023				398,878		81,511,204
Beginning balance at Mar. 31, 2023	3,004,241			$ 159,822		$ 820			3,828,930			(1,068,892)	4,546	79,015
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding amounts attributable to redeemable noncontrolling interests	61,453											60,499		954
Other comprehensive income (loss) - change in fair value of interest rate swaps, excluding portion attributable to redeemable noncontrolling interests	950												950
Dividends declared to common shareholders	(88,031)											(88,031)
Dividends declared to preferred shareholders	(2,008)											(2,008)
Distributions declared to noncontrolling interests, excluding amounts attributable to redeemable noncontrolling interests	(1,154)													(1,154)
Common shares issued, net (in shares)						32
Common shares issued, net	(59)					$ 0			(59)
Shares issued under dividend reinvestment plan (in shares)						4,967
Shares issued under dividend reinvestment plan	482								482
Share-based compensation expense, net of forfeitures (in shares)						0
Share-based compensation expense, net of forfeitures	3,696					$ 0			3,696
Shares withheld for employee taxes (in shares)						(692)
Shares withheld for employee taxes	(66)								(66)
Contributions from noncontrolling interests	927													927
Ending balance (in shares) at Jun. 30, 2023				398,878		81,515,511
Ending balance at Jun. 30, 2023	$ 2,980,431			$ 159,822		$ 820			$ 3,832,983			$ (1,098,432)	$ 5,496	$ 79,742