AvalonBay Communities (AVB) 10-Q 4 Nov 20 2020 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2020	Oct. 30, 2020
Cover [Abstract]
Document Type	10-Q
Document Period End Date	Sep. 30, 2020
Entity File Number	1-12672
Entity Registrant Name	AVALONBAY COMMUNITIES, INC.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	77-0404318
Entity Address, Address Line One	4040 Wilson Blvd., Suite 1000
Entity Address, Address City or Town	Arlington
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	22203
City Area Code	703
Local Phone Number	329-6300
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	AVB
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		139,608,983
Entity Central Index Key	0000915912
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Real estate:
Land and improvements	$ 4,392,228	$ 4,299,162
Buildings and improvements	17,093,580	16,668,496
Furniture, fixtures and equipment	913,687	829,242
Gross operating real estate	22,399,495	21,796,900
Less accumulated depreciation	(5,644,219)	(5,164,398)
Net operating real estate	16,755,276	16,632,502
Construction in progress, including land	1,200,502	1,303,751
Land held for development	43,494	0
For-sale condominium inventory	298,429	457,809
Real estate assets held for sale, net	0	38,927
Net operating real estate	18,297,701	18,432,989
Cash and cash equivalents	87,530	39,687
Cash in escrow	94,870	87,927
Resident security deposits	31,949	34,224
Investments in unconsolidated real estate entities	194,317	165,806
Deferred development costs	73,748	70,486
Prepaid expenses and other assets	206,873	164,971
Right of use lease assets	157,623	124,961
Total assets	19,144,611	19,121,051
LIABILITIES AND EQUITY
Unsecured notes, net	6,700,250	6,358,648
Variable rate unsecured credit facility	0	0
Mortgage notes payable, net	863,396	937,642
Dividends payable	225,025	215,414
Payables for construction	88,040	92,135
Accrued expenses and other liabilities	292,275	274,013
Lease liabilities	182,859	140,468
Accrued interest payable	62,248	47,154
Resident security deposits	57,683	61,752
Liabilities related to real estate assets held for sale	0	375
Total liabilities	8,471,776	8,127,601
Commitments and contingencies
Redeemable noncontrolling interests	2,593	3,252
Equity:
Preferred Stock, Value, Issued	0	0
Common Stock, Value, Issued	1,398	1,406
Additional paid-in capital	10,681,158	10,736,733
Accumulated earnings less dividends	29,705	282,913
Accumulated other comprehensive loss	(42,617)	(31,503)
Stockholders' Equity Attributable to Parent	10,669,644	10,989,549
Stockholders' Equity Attributable to Noncontrolling Interest	598	649
Total equity	10,670,242	10,990,198
Total liabilities and equity	$ 19,144,611	$ 19,121,051

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference (in dollars per share)	$ 25	$ 25
Preferred stock, shares authorized (in shares)	50,000,000	50,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	280,000,000	280,000,000
Common stock, shares issued (in shares)	139,828,685	140,643,962
Common stock, shares outstanding (in shares)	139,828,685	140,643,962

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue:
Rental and other income	$ 566,387	$ 586,382	$ 1,742,509	$ 1,727,576
Management, development and other fees	1,017	1,231	2,950	3,484
Total revenue	567,404	587,613	1,745,459	1,731,060
Expenses:
Operating expenses, excluding property taxes	143,909	133,445	406,991	389,825
Property taxes	68,934	64,374	202,973	187,890
Interest expense, net	53,249	51,493	162,562	149,395
(Gain) loss on extinguishment of debt, net	(105)	93	9,333	602
Depreciation expense	175,348	165,463	529,508	490,213
General and administrative expense	13,985	12,769	46,878	45,440
Expensed transaction, development and other pursuit costs, net of recoveries	567	175	4,289	2,562
Total expenses	455,887	427,812	1,362,534	1,265,927
Equity in income of unconsolidated real estate entities	5,083	1,643	6,770	780
Gain on sale of communities	31,607	130,484	91,338	165,849
Gain on other real estate transactions, net	129	73	328	374
Gain on for-sale condominiums, net of marketing and administrative costs	(646)	(1,108)	4,162	(2,526)
Income before income taxes	147,690	290,893	485,523	629,610
Income tax benefit (expense)	27	(11,184)	1,069	(11,178)
Net income	147,717	279,709	486,592	618,432
Net income attributable to noncontrolling interests	(14)	(32)	(90)	(108)
Net income attributable to common stockholders	147,703	279,677	486,502	618,324
Other comprehensive income (loss):
Gain (loss) on cash flow hedges	1,333	(13,644)	(17,731)	(23,763)
Cash flow hedge losses reclassified to earnings	2,367	1,746	6,617	4,825
Comprehensive income	$ 151,403	$ 267,779	$ 475,388	$ 599,386
Earnings per common share - basic:
Net income attributable to common stockholders (in dollars per share)	$ 1.05	$ 2	$ 3.46	$ 4.44
Earnings per common share - diluted:
Net income attributable to common stockholders (in dollars per share)	$ 1.05	$ 2	$ 3.46	$ 4.43

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows from operating activities:
Net income	$ 486,592	$ 618,432
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation expense	529,508	490,213
Amortization of deferred financing costs	5,617	5,458
Amortization of debt discount	1,321	1,186
(Gain) loss on extinguishment of debt, net	9,333	602
Amortization of stock-based compensation	17,753	20,810
Equity in loss of, and return on, unconsolidated real estate entities and noncontrolling interests, net of eliminations	5,204	10,787
Abandonment of development pursuits	2,095	1,080
Cash flow hedge losses reclassified to earnings	6,617	4,825
Gain on sale of real estate assets	(96,823)	(166,223)
Gain on for-sale condominiums	(8,174)	0
Increase in resident security deposits, prepaid expenses and other assets	(36,332)	(29,804)
Increase in accrued expenses, other liabilities and accrued interest payable	39,363	57,556
Net cash provided by operating activities	962,074	1,014,922
Cash flows from investing activities:
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	(562,334)	(791,551)
Acquisition of real estate assets, including partnership interest	0	(286,804)
Capital expenditures - existing real estate assets	(76,860)	(92,825)
Capital expenditures - non-real estate assets	(24,720)	(4,223)
Mortgage note receivable payments	(4,095)	(3,390)
Decrease in payables for construction	186,090	421,735
Proceeds from the sale of for-sale condominiums, net of selling costs	170,604	0
Mortgage note receivable lending	(260)	(565)
Mortgage note receivable payments	3,419	978
Proceeds from Sale of Equity Method Investments	9,877	694
Investments in unconsolidated real estate entities	(23,044)	(1,253)
Net cash used in investing activities	(321,323)	(757,204)
Cash flows from financing activities:
Issuance of common stock, net	1,599	207,789
Payments for Repurchase of Common Stock	(137,458)	0
Dividends paid	(661,000)	(627,467)
Issuance of mortgage notes payable	51,000	30,250
Repayments of mortgage notes payable, including prepayment penalties	(125,427)	(160,709)
Issuance of unsecured notes	1,296,581	449,804
Repayment of unsecured notes, including prepayment penalties	(958,681)	0
Payment of deferred financing costs	(11,278)	(10,910)
Payment for termination of forward interest rate swaps	(25,135)	(12,309)
(Payment to) contribution from noncontrolling interest	(59)	455
Payments related to tax withholding for share-based compensation	(14,752)	(15,961)
Distributions to DownREIT partnership unitholders	(36)	(34)
Distributions to joint venture and profit-sharing partners	(319)	(336)
Preferred interest obligation redemption and dividends	(1,000)	(1,400)
Net cash used in financing activities	(585,965)	(140,828)
Net increase in cash, cash equivalents and cash in escrow	54,786	116,890
Cash, cash equivalents and cash in escrow, beginning of period	127,614	217,864
Cash, cash equivalents and cash in escrow, end of period	182,400	334,754
Cash paid during the period for interest, net of amount capitalized	133,913	114,400
Supplemental Cash Flow Information [Abstract]
Cash, cash equivalents and cash in escrow reported in the Condensed Consolidated Statements of Cash Flows	$ 182,400	$ 334,754

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020USD ($)Lease	Sep. 30, 2020USD ($)Leaseshares	Sep. 30, 2019USD ($)shares	Jan. 01, 2019USD ($)
Supplemental disclosures of non-cash investing and financing activities
Common stock issued through the dividend reinvestment plan (in shares) | shares		1,967	1,594
Common stock issued through the dividend reinvestment plan		$ 339	$ 314
Number of shares withheld to satisfy employees' tax withholding and other liabilities (in shares) | shares		73,103	83,602
Shares withheld to satisfy employees' tax withholding and other liabilities, value		$ 14,752	$ 15,961
Stock issued during period, shares, share-based compensation, forfeited (in shares) | shares		7,421
Stock issued during period, value, share-based compensation, forfeited		$ 1,187	305
Dividends declared but not paid	$ 225,025	225,025
Change in redemption value of redeemable noncontrolling interest	(62)
Cash flow hedge losses reclassified to earnings	2,367	6,617	4,825
Operating Lease, Right-of-Use Asset	135,885	135,885
Total lease liabilities	162,683	162,683
Increase (Decrease) in Derivative Liabilities			$ 17,824
Increase (Decrease) in Derivative Assets		$ 1,413
Restricted Stock and Restricted Stock Converted From Performance Shares
Supplemental disclosures of non-cash investing and financing activities
Equity instruments granted (in shares) | shares		165,426	150,359
Restricted Stock Converted From Performance Shares
Supplemental disclosures of non-cash investing and financing activities
Equity instruments granted (in shares) | shares		96,317	73,072
Restricted stock
Supplemental disclosures of non-cash investing and financing activities
Equity instruments granted (in shares) | shares		69,109	77,287
Fair value of shares issued		$ 15,285	$ 15,145
Stock issued during period, shares, share-based compensation, forfeited (in shares) | shares		7,421	1,730
Common stock
Supplemental disclosures of non-cash investing and financing activities
Dividends declared but not paid	223,391	$ 223,391	$ 213,070
Accumulated earnings less dividends
Supplemental disclosures of non-cash investing and financing activities
Change in redemption value of redeemable noncontrolling interest	(62)	(387)	$ 382
Accounting Standards Update 2016-02
Supplemental disclosures of non-cash investing and financing activities
Operating Lease, Right-of-Use Asset				$ 122,276
Total lease liabilities				$ 122,276
New Office Leases
Supplemental disclosures of non-cash investing and financing activities
Operating Lease, Right-of-Use Asset	$ 46,875	$ 46,875
Number of New Office Leases | Lease	2	2
Total lease liabilities	$ 46,875	$ 46,875

Organization, Basis of Presenta

Organization, Basis of Presentation and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Organization, Basis of Presentation and Significant Accounting Policies	Organization, Basis of Presentation and Significant Accounting Policies Organization and Basis of Presentation AvalonBay Communities, Inc. (the "Company," which term, unless the context otherwise requires, refers to AvalonBay Communities, Inc. together with its subsidiaries), is a Maryland corporation that has elected to be treated as a real estate investment trust ("REIT") for federal income tax purposes under the Internal Revenue Code of 1986 (the "Code"). The Company focuses on the development, redevelopment, acquisition, ownership and operation of multifamily communities in New England, the New York/New Jersey metro area, the Mid-Atlantic, the Pacific Northwest, and Northern and Southern California, as well as in the Company's expansion markets in Southeast Florida and Denver, Colorado (the "Expansion Markets"). At September 30, 2020, the Company owned or held a direct or indirect ownership interest in 275 operating apartment communities containing 80,292 apartment homes in 11 states and the District of Columbia, of which one community containing 344 apartment homes was under redevelopment. In addition, the Company owned or held a direct or indirect ownership interest in 19 communities under development that are expected to contain an aggregate of 6,384 apartment homes when completed, as well as The Park Loggia, which contains 172 for-sale residential condominiums, of which 59 have been sold as of September 30, 2020, and 67,000 square feet of commercial space, of which 64% has been leased as of September 30, 2020. The Company also owned or held a direct or indirect ownership interest in land or rights to land on which the Company expects to develop an additional 27 communities that, if developed as expected, will contain an estimated 9,320 apartment homes. The interim unaudited financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and in conjunction with the rules and regulations of the Securities and Exchange Commission ("SEC"). Certain information and footnote disclosures normally included in financial statements required by GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited financial statements should be read in conjunction with the financial statements and notes included in the Company's 2019 Annual Report on Form 10-K. The results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the operating results for the full year. Management believes the disclosures are adequate to ensure the information presented is not misleading. In the opinion of management, all adjustments and eliminations, consisting only of normal, recurring adjustments necessary for a fair presentation of the financial statements for the interim periods, have been included. Capitalized terms used without definition have meanings provided elsewhere in this Form 10-Q. Earnings per Common Share Basic earnings per share is computed by dividing net income attributable to common stockholders by the weighted average number of shares outstanding during the period. All outstanding unvested restricted share awards contain rights to non-forfeitable dividends and participate in undistributed earnings with common shareholders and, accordingly, are considered participating securities that are included in the two-class method of computing basic earnings per share ("EPS"). Both the unvested restricted shares and other potentially dilutive common shares, and the related impact to earnings, are considered when calculating earnings per share on a diluted basis. The Company's earnings per common share are determined as follows (dollars in thousands, except per share data): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 Basic and diluted shares outstanding Weighted average common shares - basic 140,271,574 139,340,142 140,366,438 138,931,955 Weighted average DownREIT units outstanding 7,500 7,500 7,500 7,500 Effect of dilutive securities 324,648 505,032 328,865 498,609 Weighted average common shares - diluted 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 $ 279,677 $ 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 140,271,574 139,340,142 140,366,438 138,931,955 Earnings per common share - basic $ 1.05 $ 2.00 $ 3.46 $ 4.44 Calculation of Earnings per Share - diluted Net income attributable to common stockholders $ 147,703 $ 279,677 $ 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 140,603,722 139,852,674 140,702,803 139,438,064 Earnings per common share - diluted $ 1.05 $ 2.00 $ 3.46 $ 4.43 All options to purchase shares of common stock outstanding as of September 30, 2020 and 2019 are included in the computation of diluted earnings per share. Derivative Instruments and Hedging Activities The Company enters into interest rate swap and interest rate cap agreements (collectively, "Hedging Derivatives") for interest rate risk management purposes and in conjunction with certain variable rate secured debt to satisfy lender requirements. The Company does not enter into Hedging Derivative transactions for trading or other speculative purposes. The Company assesses the effectiveness of qualifying cash flow and fair value hedges, both at inception and on an on-going basis. Hedge ineffectiveness is reported as a component of interest expense, net. The fair values of Hedging Derivatives that are in an asset position are recorded in prepaid expenses and other assets. The fair value of Hedging Derivatives that are in a liability position are included in accrued expenses and other liabilities. The Company does not present or disclose the fair value of Hedging Derivatives on a net basis. Fair value changes for derivatives that are not in qualifying hedge relationships are reported as a component of interest expense, net. For the Hedging Derivative positions that the Company has determined qualify as effective cash flow hedges, the Company has recorded the cumulative changes in the fair value of Hedging Derivatives in other comprehensive loss. Amounts recorded in accumulated other comprehensive loss will be reclassified into earnings in the periods in which earnings are affected by the hedged cash flow. The effective portion of the change in fair value of the Hedging Derivatives that the Company has determined qualified as effective fair value hedges is reported as an adjustment to the carrying amount of the corresponding debt being hedged. See Note 11, "Fair Value," for further discussion of derivative financial instruments. Legal and Other Contingencies The Company is involved in various claims and/or administrative proceedings that arise in the ordinary course of its business. While no assurances can be given, the Company does not currently believe that any of these outstanding litigation matters, individually or in the aggregate, will have a material adverse effect on its financial condition or results of operations. Acquisitions of Investments in Real Estate The Company accounts for acquisitions of investments in real estate in accordance with the authoritative guidance for the initial measurement, which first requires that the Company determine if the real estate investment is the acquisition of an asset or a business combination. Under either model, the Company must identify and determine the fair value of any assets acquired, liabilities assumed and any noncontrolling interest in the acquiree. Typical assets acquired and liabilities assumed include land, building, furniture, fixtures and equipment, debt and identified intangible assets and liabilities, consisting of the value of above or below market leases and in-place leases. In making estimates of fair values for purposes of allocating purchase price, the Company utilizes various sources, including its own analysis of recently acquired and existing comparable properties in its portfolio and other market data. Consideration for acquisitions is typically in the form of cash unless otherwise disclosed. For a business combination, the Company records the assets acquired and liabilities assumed based on the fair value of each respective item. For an asset acquisition, the allocation of the purchase price is based on the relative fair value of the net assets. The Company expenses all applicable acquisition costs for a business combination and capitalizes all applicable acquisition costs for an asset acquisition. The Company expects that acquisitions of individual operating communities will generally be viewed as asset acquisitions. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. These estimates and assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the dates of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Actual results could differ from those estimates. Reclassifications Certain reclassifications have been made to amounts in prior years' notes to financial statements to conform to current year presentations as a result of changes in held for sale classification, disposition activity and segment classification. For-Sale Condominium Inventory The Company presents for-sale condominium inventory at historical cost and evaluates the condominium inventory for impairment when potential indicators exist, as further discussed in Note 6, "Real Estate Disposition Activities." Leases The Company is party to leases as both a lessor and a lessee, primarily as follows: • lessor of residential and commercial space within its apartment communities; and • lessee under (i) ground leases for land underlying current operating or development communities and (ii) office leases for its corporate headquarters and regional offices. Lessee Considerations The Company assesses whether a contract is or contains a lease based on whether the contract conveys the right to control the use of an identified asset, including specified portions of larger assets, for a period of time in exchange for consideration. The Company’s leases include both fixed and variable lease payments, which are based on an index or rate such as the consumer price index (CPI) or percentage rents based on total sales. Lease payments included in the lease liability include only payments that depend on an index or rate. For leases that have options to extend the term or terminate the lease early, the Company only factored the impact of such options into the lease term if the option was considered reasonably certain to be exercised. The Company determined the discount rate associated with its ground and office leases on a lease by lease basis using the Company’s actual borrowing rates as well as indicative market pricing for longer term rates and taking into consideration the remaining term of each of the lease agreements. Lessor Considerations The Company evaluates leases in which it is the lessor, which are composed of residential and commercial leases at its apartment communities, and determined these leases to be operating leases. For lease agreements that provide for rent concessions and/or scheduled fixed and determinable rent increases, rental income is recognized on a straight-line basis over the noncancellable term of the lease, which, for residential leases, is generally one year. Some of the Company’s commercial leases have fixed-price renewal options, and the lessee may be able to exercise its renewal option at an amount less than the fair value of the rent at such time. The Company only includes renewal options in the lease term if, at the commencement of the lease, it is reasonably certain that the lessee will exercise this option. Revenue and Gain Recognition Revenue from contracts with customers is recognized in accordance with the transfer of goods and services to customers at an amount that reflects the consideration that the Company expects to be entitled to for those goods and services. The majority of the Company’s revenue is derived from residential and commercial rental income and other lease income, which are accounted for under ASC 842, Leases, discussed above. The Company's revenue streams that are not accounted for under ASC 842 include (i) management fees, (ii) rental and non-rental related income and (iii) gains or losses on the sale of real estate. The following table provides details of the Company’s revenue streams disaggregated by the Company’s reportable operating segments, further discussed in Note 8, “Segment Reporting,” for the three and nine months ended September 30, 2020 and 2019. Segment information for total revenue has been adjusted to exclude the real estate assets that were sold from January 1, 2019 through September 30, 2020, or otherwise qualify as held for sale as of September 30, 2020, as described in Note 6, "Real Estate Disposition Activities" (dollars in thousands): For the three months ended Established Other Development/ Non- Total For the period ended September 30, 2020 Management, development and other fees $ — $ — $ — $ 1,017 $ 1,017 Rental and non-rental related income (2) 1,959 477 337 — 2,773 Total non-lease revenue (3) 1,959 477 337 1,017 3,790 Lease income (4) 506,587 34,333 20,963 — 561,883 Business interruption insurance proceeds 12 270 — — 282 Total revenue $ 508,558 $ 35,080 $ 21,300 $ 1,017 $ 565,955 For the period ended September 30, 2019 Management, development and other fees $ — $ — $ — $ 1,231 $ 1,231 Rental and non-rental related income (2) 1,796 445 133 — 2,374 Total non-lease revenue (3) 1,796 445 133 1,231 3,605 Lease income (4) 539,634 29,754 8,219 — 577,607 Business interruption insurance proceeds 307 — — — 307 Total revenue $ 541,737 $ 30,199 $ 8,352 $ 1,231 $ 581,519 For the nine months ended Established Other Development/ Non- Total For the period ended September 30, 2020 Management, development and other fees $ — $ — $ — $ 2,950 $ 2,950 Rental and non-rental related income (2) 5,416 1,271 884 — 7,571 Total non-lease revenue (3) 5,416 1,271 884 2,950 10,521 Lease income (4) 1,567,170 103,705 57,519 — 1,728,394 Business interruption insurance proceeds 115 270 — — 385 Total revenue $ 1,572,701 $ 105,246 $ 58,403 $ 2,950 $ 1,739,300 For the period ended September 30, 2019 Management, development and other fees $ — $ — $ — $ 3,484 $ 3,484 Rental and non-rental related income (2) 5,753 1,078 224 — 7,055 Total non-lease revenue (3) 5,753 1,078 224 3,484 10,539 Lease income (4) 1,599,224 76,671 15,596 — 1,691,491 Business interruption insurance proceeds 914 — — — 914 Total revenue $ 1,605,891 $ 77,749 $ 15,820 $ 3,484 $ 1,702,944 __________________________________ (1) Revenue represents third-party management, asset management and developer fees and miscellaneous income which are not allocated to a reportable segment. (2) Amounts include revenue streams related to leasing activities that are not considered components of a lease, including but not limited to, apartment hold fees and application fees, as well as revenue streams not related to leasing activities, including but not limited to, vendor revenue sharing, building advertising, vending and dry cleaning revenue. (3) Represents all revenue accounted for under ASU 2014-09. (4) Amounts include all revenue streams derived from residential and commercial rental income and other lease income, which are accounted for under ASC 842. Due to the nature and timing of the Company’s identified revenue streams, there are no material amounts of outstanding or unsatisfied performance obligations as of September 30, 2020. COVID-19 Pandemic In March 2020, the World Health Organization designated COVID-19 as a pandemic. While the Company has taken various actions in response to the COVID-19 pandemic, the ultimate impact on its consolidated results of operations, cash flows, financial condition and liquidity will depend on (i) the duration and severity of the pandemic, (ii) the duration and nature of governmental responses to contain the spread of the disease and assist consumers and businesses, (iii) consumer and business responses to the pandemic, including preference for where and how to live and work, and (iv) how quickly and to what extent normal economic and operating conditions can resume. Because of this uncertainty, the Company is not able to estimate the expected impact of the COVID-19 pandemic on its results of operations, cash flows, financial condition, or liquidity for the year ending December 31, 2020 at this time. As of September 30, 2020, the Company assessed the collectibility of the outstanding lease income receivables as a result of the impact of the COVID-19 pandemic on its residential and commercial lease portfolios. The Company recorded an aggregate offset to income for uncollectible lease revenue for its residential and commercial portfolios of $18,755,000 and $43,034,000 for the three and nine months ended September 30, 2020, respectively, under ASC 842 and ASC 450, Contingencies. Recently Issued and Adopted Accounting Standards In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. This ASU requires entities to estimate a lifetime expected credit loss for most financial assets, including (i) trade and other receivables, (ii) other long term financings including available for sale and held-to-maturity debt securities and (iii) loans. Subsequently, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, which amends the scope of ASU 2016-13 and clarified that receivables arising from operating leases are not within the scope of the standard and should continue to be accounted for in accordance with the leases standard (Topic 842). The new standard was adopted on January 1, 2020 and does not have a material effect on the Company’s financial position or results of operations.

Interest Capitalized

Interest Capitalized	9 Months Ended
	Sep. 30, 2020
Interest Capitalized
Interest Capitalized	Interest CapitalizedThe Company capitalizes interest during the development and redevelopment of real estate assets. Capitalized interest associated with the Company's development or redevelopment activities totaled $11,221,000 and $15,443,000 for the three months ended September 30, 2020 and 2019, respectively, and $33,738,000 and $50,159,000 for the nine months ended September 30, 2020 and 2019, respectively.

Mortgage Notes Payable, Unsecur

Mortgage Notes Payable, Unsecured Notes and Credit Facility	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Notes Payable, Unsecured Notes and Credit Facility	Mortgage Notes Payable, Unsecured Notes, Term Loans and Credit Facility The Company's mortgage notes payable, unsecured notes, variable rate unsecured term loans (the "Term Loans") and Credit Facility, as defined below, as of September 30, 2020 and December 31, 2019 are summarized below. The following amounts and discussion do not include the mortgage notes related to the communities classified as held for sale, if any, as of September 30, 2020 and December 31, 2019, as shown in the accompanying Condensed Consolidated Balance Sheets (dollars in thousands) (see Note 6, "Real Estate Disposition Activities"). 9/30/2020 12/31/2019 Fixed rate unsecured notes (1) $ 6,500,000 $ 5,850,000 Variable rate unsecured notes (1) — 300,000 Term Loans (1) 250,000 250,000 Fixed rate mortgage notes payable - conventional and tax-exempt (2) 409,649 479,221 Variable rate mortgage notes payable - conventional and tax-exempt (2) 471,450 476,150 Total mortgage notes payable and unsecured notes and Term Loans 7,631,099 7,355,371 Credit Facility — — Total mortgage notes payable, unsecured notes, Term Loans and Credit Facility $ 7,631,099 $ 7,355,371 _____________________________________ (1) Balances at September 30, 2020 and December 31, 2019 exclude $10,782 and $8,610, respectively, of debt discount, and $38,968 and $32,742, respectively, of deferred financing costs, as reflected in unsecured notes, net on the accompanying Condensed Consolidated Balance Sheets. (2) Balances at September 30, 2020 and December 31, 2019 exclude $14,636 and $14,464, respectively, of debt discount, and $3,067 and $3,265, respectively, of deferred financing costs, as reflected in mortgage notes payable, net on the accompanying Condensed Consolidated Balance Sheets. The following debt activity occurred during the nine months ended September 30, 2020: • In February 2020, the Company issued $700,000,000 principal amount of unsecured notes in a public offering under its existing shelf registration statement for net proceeds of approximately $694,701,000. The notes mature in March 2030 and were issued at a 2.30% interest rate. • In February 2020, the Company refinanced the secured borrowing for Avalon San Bruno III. The secured borrowing had a fixed interest rate of 3.08% and was refinanced for a principal balance of $51,000,000, with a fixed interest rate of 2.38% and maturity date of March 2027. • In March 2020, the Company repaid (i) $400,000,000 principal amount of its 3.625% unsecured notes in advance of the October 2020 scheduled maturity and (ii) $250,000,000 principal amount of its 3.95% unsecured notes in advance of the January 2021 scheduled maturity. In conjunction with these repayments, the Company recognized a loss on debt extinguishment of $9,170,000 for prepayment penalties and the non-cash write-off of unamortized deferred financing costs. • In May 2020, the Company issued $600,000,000 principal amount of unsecured notes in a public offering under its existing shelf registration statement for net proceeds of approximately $593,430,000. The notes mature in January 2031 and were issued at a 2.45% interest rate. • In May 2020, the Company repaid $300,000,000 principal amount of its variable rate unsecured notes in advance of the January 2021 scheduled maturity, recognizing a charge of $268,000 for the non-cash write-off of deferred financing costs. • In August 2020, the Company repaid $67,904,000 principal amount of 4.18% fixed rate debt secured by Avalon Hoboken at par in advance of its December 2020 maturity date. At September 30, 2020, the Company had a $1,750,000,000 revolving variable rate unsecured credit facility with a syndicate of banks (the “Credit Facility”) which matures in February 2024. The Credit Facility bears interest at varying levels based on (i) the London Interbank Offered Rate (“LIBOR”) applicable to the period of borrowing for a particular draw of funds from the facility (e.g., one month to maturity, three months to maturity, etc.) and (ii) the rating levels issued for our unsecured notes. The current stated pricing for drawn borrowings is LIBOR plus 0.775% per annum (0.92% at September 30, 2020), assuming a one month borrowing rate. The annual facility fee is 0.125% (or approximately $2,188,000 annually based on the $1,750,000,000 facility size and based on the Company's current credit rating). The Company had no borrowings outstanding under the Credit Facility as of September 30, 2020 and December 31, 2019. The Company had $3,752,000 and $11,488,000 outstanding in letters of credit that reduced the borrowing capacity as of September 30, 2020 and December 31, 2019, respectively. In addition, the Company had $31,822,000 and $24,939,000 outstanding in additional letters of credit on a separate facility unrelated to the Credit Facility as of September 30, 2020 and December 31, 2019, respectively. In the aggregate, secured notes payable mature at various dates from April 2021 through July 2066, and are secured by certain apartment communities (with a net carrying value of $1,455,524,000, excluding communities classified as held for sale, as of September 30, 2020). The weighted average interest rate of the Company's fixed rate secured notes payable (conventional and tax-exempt) was 3.8% and 3.9% at September 30, 2020 and December 31, 2019, respectively. The weighted average interest rate of the Company's variable rate secured notes payable (conventional and tax-exempt) including the effect of certain financing related fees, was 1.7% and 3.2% at September 30, 2020 and December 31, 2019, respectively. Scheduled payments and maturities of secured notes payable and unsecured notes outstanding at September 30, 2020 are as follows (dollars in thousands): Year Secured notes Secured notes maturities Unsecured notes and Term Loans maturities Stated interest rate of unsecured notes and Term Loans 2020 $ 1,285 $ — $ — N/A 2021 9,304 27,844 — N/A 2022 9,918 — 450,000 2.950 % 100,000 LIBOR + 0.90% 2023 10,739 — 350,000 4.200 % 250,000 2.850 % 2024 11,677 — 300,000 3.500 % 150,000 LIBOR + 0.85% 2025 12,408 — 525,000 3.450 % 300,000 3.500 % 2026 13,445 — 475,000 2.950 % 300,000 2.900 % 2027 15,080 236,100 400,000 3.350 % 2028 20,607 — 450,000 3.200 % 2029 11,742 66,250 450,000 3.300 % Thereafter 189,362 245,338 700,000 2.300 % 600,000 2.450 % 350,000 3.900 % 300,000 4.150 % 300,000 4.350 % $ 305,567 $ 575,532 $ 6,750,000 The Company was in compliance at September 30, 2020 with customary financial covenants under the Credit Facility, the Term Loans and the Company's fixed rate unsecured notes.

Equity

Equity	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity Note [Abstract]
Equity	Equity The following summarizes the changes in equity for the nine months ended September 30, 2020 (dollars in thousands): Common Additional Accumulated Accumulated Total AvalonBay stockholder's equity Noncontrolling interests Total Balance at December 31, 2019 $ 1,406 $ 10,736,733 $ 282,913 $ (31,503) $ 10,989,549 $ 649 $ 10,990,198 Net income attributable to common stockholders — — 167,971 — 167,971 — 167,971 Loss on cash flow hedges, net — — — (17,603) (17,603) — (17,603) Cash flow hedge losses reclassified to earnings — — — 1,949 1,949 — 1,949 Change in redemption value of redeemable noncontrolling interest — — 471 — 471 — 471 Noncontrolling interest distribution and income allocation — — — — — (35) (35) Dividends declared to common stockholders ($1.59 per share) — — (224,083) — (224,083) — (224,083) Issuance of common stock, net of withholdings 1 (12,492) (1,616) — (14,107) — (14,107) Amortization of deferred compensation — 7,781 — — 7,781 — 7,781 Balance at March 31, 2020 $ 1,407 $ 10,732,022 $ 225,656 $ (47,157) $ 10,911,928 $ 614 $ 10,912,542 Net income attributable to common stockholders — — 170,828 — 170,828 — 170,828 Loss on cash flow hedges, net — — — (1,461) (1,461) — (1,461) Cash flow hedge losses reclassified to earnings — — — 2,301 2,301 — 2,301 Change in redemption value of redeemable noncontrolling interest — — (146) — (146) — (146) Noncontrolling interest distribution and income allocation — — — — — 1 1 Dividends declared to common stockholders ($1.59 per share) — — (224,172) — (224,172) — (224,172) Issuance of common stock, net of withholdings — 1,050 138 — 1,188 — 1,188 Amortization of deferred compensation — 9,724 — — 9,724 — 9,724 Balance at June 30, 2020 $ 1,407 $ 10,742,796 $ 172,304 $ (46,317) $ 10,870,190 $ 615 $ 10,870,805 Net income attributable to common stockholders — — 147,703 — 147,703 — 147,703 Gain on cash flow hedges, net — — — 1,333 1,333 — 1,333 Cash flow hedge losses reclassified to earnings — — — 2,367 2,367 — 2,367 Change in redemption value of redeemable noncontrolling interest — — 62 — 62 — 62 Noncontrolling interest distribution and income allocation — — — — — (17) (17) Dividends declared to common stockholders ($1.59 per share) — — (222,694) — (222,694) — (222,694) Issuance of common stock, net of withholdings — 105 — — 105 — 105 Repurchase of common stock, including repurchase costs (9) (69,779) (67,670) — (137,458) — (137,458) Amortization of deferred compensation — 8,036 — — 8,036 — 8,036 Balance at September 30, 2020 $ 1,398 $ 10,681,158 $ 29,705 $ (42,617) $ 10,669,644 $ 598 $ 10,670,242 The following summarizes the changes in equity for the nine months ended September 30, 2019 (dollars in thousands): Common Additional Accumulated Accumulated Total AvalonBay stockholder's equity Noncontrolling interests Total Balance at December 31, 2018 $ 1,385 $ 10,306,588 $ 350,777 $ (26,144) $ 10,632,606 $ — $ 10,632,606 Net income attributable to common stockholders — — 170,366 — 170,366 — 170,366 Loss on cash flow hedges, net — — — (7,231) (7,231) — (7,231) Cash flow hedge losses reclassified to earnings — — — 1,468 1,468 — 1,468 Change in redemption value of redeemable noncontrolling interest — — (224) — (224) — (224) Dividends declared to common stockholders ($1.52 per share) — — (212,166) — (212,166) — (212,166) Issuance of common stock, net of withholdings 9 143,202 (1,892) — 141,319 — 141,319 Amortization of deferred compensation — 7,861 — — 7,861 — 7,861 Balance at March 31, 2019 $ 1,394 $ 10,457,651 $ 306,861 $ (31,907) $ 10,733,999 $ — $ 10,733,999 Net income attributable to common stockholders — — 168,281 — 168,281 — 168,281 Loss on cash flow hedges, net — — — (2,888) (2,888) — (2,888) Cash flow hedge losses reclassified to earnings — — — 1,611 1,611 — 1,611 Change in redemption value of redeemable noncontrolling interest — — (45) — (45) — (45) Noncontrolling interests income allocation — — — — — 530 530 Dividends declared to common stockholders ($1.52 per share) — — (212,549) — (212,549) — (212,549) Issuance of common stock, net of withholdings 3 50,803 — — 50,806 — 50,806 Amortization of deferred compensation — 10,785 — — 10,785 — 10,785 Balance at June 30, 2019 $ 1,397 $ 10,519,239 $ 262,548 $ (33,184) $ 10,750,000 $ 530 $ 10,750,530 Net income attributable to common stockholders — — 279,677 — 279,677 — 279,677 Loss on cash flow hedges, net — — — (13,644) (13,644) — (13,644) Cash flow hedge losses reclassified to earnings — — — 1,746 1,746 — 1,746 Change in redemption value of redeemable noncontrolling interest — — (113) — (113) — (113) Noncontrolling interests income allocation — — — — — 118 118 Dividends declared to common stockholders ($1.52 per share) — — (212,526) — (212,526) — (212,526) Issuance of common stock, net of withholdings — (454) (263) — (717) — (717) Amortization of deferred compensation — 10,002 — — 10,002 — 10,002 Balance at September 30, 2019 $ 1,397 $ 10,528,787 $ 329,323 $ (45,082) $ 10,814,425 $ 648 $ 10,815,073 As of September 30, 2020 and December 31, 2019, the Company's charter had authorized for issuance a total of 280,000,000 shares of common stock and 50,000,000 shares of preferred stock. During the nine months ended September 30, 2020, the Company: i. issued 1,902 shares of common stock in connection with stock options exercised; ii. issued 1,967 common shares through the Company's dividend reinvestment plan; iii. issued 165,426 common shares in connection with restricted stock grants and the conversion of performance awards to restricted shares; iv. withheld 73,103 common shares to satisfy employees' tax withholding and other liabilities; v. issued 8,685 common shares through the Employee Stock Purchase Plan; vi. canceled 7,421 common shares of restricted stock upon forfeiture; and vii. purchased 912,733 common shares through the 2020 Stock Repurchase Program. Any deferred compensation related to the Company's stock option, restricted stock and performance award grants during the nine months ended September 30, 2020 is not reflected on the accompanying Condensed Consolidated Balance Sheets as of September 30, 2020, and will not be reflected until recognized as compensation cost. In July 2020, the Company’s Board of Directors voted to terminate the Company’s prior $500,000,000 Stock Repurchase Program (the "Amended 2005 Stock Repurchase Program") and approved a new stock repurchase program under which the Company may acquire shares of its common stock in open market or negotiated transactions up to an aggregate purchase price of $500,000,000 (the "2020 Stock Repurchase Program"). Purchases of common stock under the 2020 Stock Repurchase Program may be exercised from time to time in the Company’s discretion and in such amounts as market conditions warrant. The timing and actual number of shares repurchased will depend on a variety of factors including price, corporate and regulatory requirements, market conditions and other corporate liquidity requirements and priorities. The 2020 Stock Repurchase Program does not have an expiration date and may be suspended or terminated at any time without prior notice. During the three months ended September 30, 2020, the Company repurchased 912,733 shares of common stock at an average price of $150.58 per share. As of September 30, 2020, the Company had $362,560,000 remaining authorized for purchase under this program. In May 2019, the Company commenced a fifth continuous equity program ("CEP V") under which the Company may sell (and/or enter into forward sale agreements for the sale of) up to $1,000,000,000 of its common stock from time to time. Actual sales will depend on a variety of factors to be determined by the Company, including market conditions, the trading price of the Company's common stock and determinations by the Company of the appropriate sources of funding for the Company. In conjunction with CEP V, the Company engaged sales agents who will receive compensation of up to 1.5% of the gross sales price for shares sold. The Company expects that, if entered into, it will physically settle each forward sale agreement on one or more dates specified by the Company on or prior to the maturity date of that particular forward sale agreement, in which case the Company will expect to receive aggregate net cash proceeds at settlement equal to the number of shares underlying the particular forward agreement multiplied by the relevant forward sale price. However, the Company may also elect to cash settle or net share settle a forward sale agreement. In connection with each forward sale agreement, the Company will pay the relevant forward seller, in the form of a reduced initial forward sale price, a commission of up to 1.5% of the sales prices of all borrowed shares of common stock sold. During the three and nine months ended September 30, 2020, the Company had no sales under the program. As of September 30, 2020, the Company had $752,878,000 remaining authorized for issuance under this program.

Investments in Real Estate Enti

Investments in Real Estate Entities	9 Months Ended
	Sep. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Investments in Real Estate Entities	Investments in Real Estate Entities Investments in Unconsolidated Real Estate Entities As of September 30, 2020, the Company had investments in eight unconsolidated real estate entities with ownership interest percentages ranging from 20.0% to 50.0%. The Company accounts for its investments in unconsolidated real estate entities under the equity method of accounting. The significant accounting policies of the Company's unconsolidated real estate entities are consistent with those of the Company in all material respects. During the three and nine months ended September 30, 2020, Archstone Multifamily Partners AC LP (the "U.S. Fund") sold Avalon Venice on Rose, located in Venice, CA, containing 70 apartment homes and 9,000 square feet of commercial space for $65,000,000. The Company's share of the gain was $5,157,000. In conjunction with the disposition of this community, the U.S. Fund repaid $27,117,000 of secured indebtedness at par. During the three and nine months ended September 30, 2020, the Company entered into a joint venture to develop, own, and operate AVA Arts District, an apartment community located in Los Angeles, CA, which is currently under construction and expected to contain 475 apartment homes when complete. The Company has a 25.0% interest in the venture, and the venture partner owns the remaining 75.0% interest. The Company's total expected equity investment is approximately $27,600,000, of which $14,800,000 has already been contributed. The venture has secured a $165,600,000 variable rate construction loan to fund approximately 60% of the development of AVA Arts District, of which no amounts have been drawn as of September 30, 2020. The venture will commence draws under the loan subsequent to required equity contributions by the venture partners. The Company has guaranteed the construction loan on behalf of the venture, and any obligations under the construction loan guarantee, except for obligations arising from misconduct by the Company, are required capital contributions of the partners based on ownership interest. The venture is considered an unconsolidated VIE as the Company was not considered to be the primary beneficiary due to shared control and decision making with its venture partner. The Company and its venture partner share decision making authority for all significant aspects of the venture's activities including, but not limited to, changes in the ownership, changes to the development plan or budget, and major operating decisions including annual business plans. The following is a combined summary of the financial position of the entities accounted for using the equity method discussed above as of the dates presented, including development joint ventures started and unconsolidated communities sold during the respective periods (dollars in thousands): 9/30/2020 12/31/2019 (unaudited) Assets: Real estate, net $ 1,222,762 $ 1,204,470 Other assets 265,048 196,488 Total assets $ 1,487,810 $ 1,400,958 Liabilities and partners' capital: Mortgage notes payable, net (1) $ 749,555 $ 782,257 Other liabilities 158,875 157,379 Partners' capital 579,380 461,322 Total liabilities and partners' capital $ 1,487,810 $ 1,400,958 _________________________________ (1) The Company has not guaranteed the outstanding debt, nor does the Company have any obligation to fund this debt should the unconsolidated entity be unable to do so. The following is a combined summary of the operating results of the entities accounted for using the equity method discussed above for the periods presented (dollars in thousands): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 (unaudited) (unaudited) Rental and other income $ 28,800 $ 37,382 $ 92,299 $ 108,635 Operating and other expenses (12,782) (14,535) (37,034) (42,624) Gain on sale of communities 18,408 — 18,448 — Interest expense, net (8,024) (8,385) (24,133) (25,482) Depreciation expense (8,704) (9,324) (26,106) (49,366) Net income (loss) $ 17,698 $ 5,138 $ 23,474 $ (8,837) Company's share of net income (loss) (1) $ 5,611 $ 2,175 $ 8,357 $ 2,377 Amortization of excess investment and other (528) (532) (1,587) (1,597) Equity in income from unconsolidated real estate investments $ 5,083 $ 1,643 $ 6,770 $ 780 _________________________________ (1) Includes the Company's share of gain on sale of communities. Expensed Transaction, Development and Other Pursuit Costs The Company capitalizes pre-development costs incurred in pursuit of new development opportunities for which the Company currently believes future development is probable ("Development Rights"). Future development of these Development Rights is dependent upon various factors, including zoning and regulatory approval, rental market conditions, construction costs and the availability of capital. Initial pre-development costs incurred for pursuits for which future development is not yet considered probable are expensed as incurred. In addition, if the status of a Development Right changes, making future development by the Company no longer probable, any non-recoverable capitalized pre-development costs are expensed. The Company expensed costs related to development pursuits not yet considered probable for development and the abandonment of Development Rights, as well as costs incurred in pursuing the acquisition or disposition of assets for which such acquisition and disposition activity did not occur, in the amounts of $4,289,000 and $2,562,000 for the nine months ended September 30, 2020 and 2019, respectively. These costs are included in expensed transaction, development and other pursuit costs, net of recoveries on the accompanying Condensed Consolidated Statements of Comprehensive Income. Abandoned pursuit costs can vary greatly, and the costs incurred in any given period may be significantly different in future periods. Casualty and Impairment of Long-Lived Assets In the Company's evaluation of its real estate portfolio for impairment, as discussed below, it considered the impact of the COVID-19 pandemic and did not identify any indicators of impairment as a result. The Company evaluates its real estate and other long-lived assets for impairment when potential indicators of impairment exist. Such assets are stated at cost, less accumulated depreciation and amortization, unless the carrying amount of the asset is not recoverable. If events or circumstances indicate that the carrying amount of a property or long-lived asset may not be recoverable, the Company assesses its recoverability by comparing the carrying amount of the property or long-lived asset to its estimated undiscounted future cash flows. If the carrying amount exceeds the aggregate undiscounted future cash flows, the Company recognizes an impairment loss to the extent the carrying amount exceeds the estimated fair value of the property or long-lived asset. Based on periodic tests of recoverability of long-lived assets, the Company did not recognize any impairment losses for the three and nine months ended September 30, 2020 and 2019. The Company evaluates its for-sale condominium inventory for potential indicators of impairment, considering whether the fair value of the for-sale condominium units exceeds the carrying value. For-sale condominium inventory is stated at cost, unless the carrying amount of the inventory is not recoverable when compared to the fair value. The Company determines the fair value of its for-sale condominium inventory as the estimated sales price less direct costs to sell. In addition, the Company incurs marketing and administrative costs related to the for-sale condominiums. For the three and nine months ended September 30, 2020 and 2019, the Company did not identify any indicators of impairment for its for-sale condominium inventory. The Company assesses its portfolio of land held for both development and investment for impairment if the intent of the Company changes with respect to either the development of, or the expected holding period for, the land. During the three and nine months ended September 30, 2020 and 2019, the Company did not recognize any impairment charges on its investment in land. The Company evaluates its unconsolidated investments for other than temporary impairment, considering both the extent and amount by which the carrying value of the investment exceeds the fair value, and the Company's intent and ability to hold the investment to recover its carrying value. The Company also evaluates its proportionate share of any impairment of assets held by unconsolidated investments. There were no other than temporary impairment losses recognized for any of the Company's investments in unconsolidated real estate entities, or impairments recognized by those entities, during the three and nine months ended September 30, 2020 and 2019.

Real Estate Disposition Activit

Real Estate Disposition Activities	9 Months Ended
	Sep. 30, 2020
Discontinued Operations and Disposal Groups [Abstract]
Real Estate Disposition Activities	Real Estate Disposition Activities The following real estate sales occurred during the nine months ended September 30, 2020: Community Name Location Period of sale Apartment homes Gross sales price Gain on Disposition (1) Avalon Shelton Shelton, CT Q120 250 $ 64,750 $ 24,413 Avalon Tinton Falls Tinton Falls, NJ Q220 216 $ 64,900 $ 35,297 Avalon Towers Long Beach, NY Q320 109 $ 54,000 $ 31,603 _________________________________ (1) Gain on disposition was reported in gain on sale of communities on the accompanying Condensed Consolidated Statements of Comprehensive Income. At September 30, 2020, the Company had no real estate assets that qualified as held for sale. The Park Loggia The Park Loggia, located in New York, NY, contains 172 for-sale residential condominiums and 67,000 square feet of commercial space. During the three and nine months ended September 30, 2020, the Company sold seven and 59 residential condominiums at The Park Loggia, for gross proceeds of $15,699,000 and $182,512,000, respectively, resulting in a gain in accordance with GAAP of $727,000 and $8,174,000, respectively. The Company incurred $1,373,000 and $1,108,000 during the three months ended September 30, 2020 and 2019, respectively, and $4,012,000 and $2,526,000 during the nine months ended September 30, 2020 and 2019, respectively, in marketing and administrative costs associated with The Park Loggia. All amounts are included in gain (loss) on for-sale condominiums, net of marketing and administrative costs, on the accompanying Condensed Consolidated Statements of Comprehensive Income. As of September 30, 2020, the unsold for-sale residential condominiums at The Park Loggia have an aggregate carrying value of $298,429,000, presented as for-sale condominium inventory on the accompanying Condensed Consolidated Balance Sheets.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2020
Leases [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Obligations The Company owns 11 apartment communities, one community under development and two commercial properties, located on land subject to ground leases expiring between October 2026 and March 2142. The Company has purchase options for all ground leases expiring prior to 2030, which allow the Company to buyout the respective leases for nominal consideration as such leases were structured public finance vehicles. The ground leases for 10 of 11 of the apartment communities and the rest of the ground leases are accounted for as operating leases, with rental expense recognized on a straight-line basis over the lease term. In addition, the Company is party to 15 leases for its corporate and regional offices with varying terms through 2031, all of which are accounted for or will be accounted for as operating leases. As of September 30, 2020 and December 31, 2019, the Company has total operating lease assets of $135,885,000 and $103,063,000, respectively, and total operating lease obligations of $162,683,000 and $120,261,000, respectively, reported as components of right of use lease assets and lease liabilities, respectively, on the accompanying Condensed Consolidated Balance Sheets. The Company incurred costs of $3,958,000 and $3,618,000 for the three months ended September 30, 2020 and 2019, respectively, and $12,115,000 and $10,723,000 for the nine months ended September 30, 2020 and 2019, respectively, related to operating leases. The Company has one apartment community located on land subject to a ground lease and two leases for portions of parking garages, adjacent to apartment communities, that are accounted for as finance leases. As of September 30, 2020 and December 31, 2019, the Company has total finance lease assets of $21,738,000 and $21,898,000, respectively, and total finance lease obligations of $20,176,000 and $20,207,000, respectively, reported as components of right of use lease assets and lease liabilities, respectively, on the accompanying Condensed Consolidated Balance Sheets.
Commitments and Contingencies	Commitments and Contingencies Lease Obligations The Company owns 11 apartment communities, one community under development and two commercial properties, located on land subject to ground leases expiring between October 2026 and March 2142. The Company has purchase options for all ground leases expiring prior to 2030, which allow the Company to buyout the respective leases for nominal consideration as such leases were structured public finance vehicles. The ground leases for 10 of 11 of the apartment communities and the rest of the ground leases are accounted for as operating leases, with rental expense recognized on a straight-line basis over the lease term. In addition, the Company is party to 15 leases for its corporate and regional offices with varying terms through 2031, all of which are accounted for or will be accounted for as operating leases. As of September 30, 2020 and December 31, 2019, the Company has total operating lease assets of $135,885,000 and $103,063,000, respectively, and total operating lease obligations of $162,683,000 and $120,261,000, respectively, reported as components of right of use lease assets and lease liabilities, respectively, on the accompanying Condensed Consolidated Balance Sheets. The Company incurred costs of $3,958,000 and $3,618,000 for the three months ended September 30, 2020 and 2019, respectively, and $12,115,000 and $10,723,000 for the nine months ended September 30, 2020 and 2019, respectively, related to operating leases. The Company has one apartment community located on land subject to a ground lease and two leases for portions of parking garages, adjacent to apartment communities, that are accounted for as finance leases. As of September 30, 2020 and December 31, 2019, the Company has total finance lease assets of $21,738,000 and $21,898,000, respectively, and total finance lease obligations of $20,176,000 and $20,207,000, respectively, reported as components of right of use lease assets and lease liabilities, respectively, on the accompanying Condensed Consolidated Balance Sheets.

Segment Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Segment Reporting	Segment Reporting The Company's reportable operating segments include Established Communities, Other Stabilized Communities, and Development/Redevelopment Communities. Annually as of January 1, the Company determines which of its communities fall into each of these categories and generally maintains that classification throughout the year for the purpose of reporting segment operations, unless disposition or redevelopment plans regarding a community change. In addition, the Company owns land for future development and has other corporate assets that are not allocated to an operating segment. The Company's segment disclosures present the measure(s) used by the chief operating decision maker for purposes of assessing each segment's performance. The Company's chief operating decision maker ("CODM") is comprised of several members of its executive management team who use net operating income ("NOI") as the primary financial measure for Established Communities and Other Stabilized Communities. NOI is defined by the Company as total property revenue less direct property operating expenses (including property taxes), and excluding corporate-level income (including management, development and other fees), corporate-level property management and other indirect operating expenses, expensed transaction, development and other pursuit costs, net of recoveries, interest expense, net, (gain) loss on extinguishment of debt, net, general and administrative expense, equity in income of unconsolidated real estate entities, depreciation expense, corporate income tax expense, casualty and impairment (gain) loss, net, gain on sale of communities, (gain) loss on other real estate transactions, net, gain on for-sale condominiums, net of marketing and administrative costs and net operating income from real estate assets sold or held for sale. Although the Company considers NOI a useful measure of a community's or communities' operating performance, NOI should not be considered an alternative to net income or net cash flow from operating activities, as determined in accordance with GAAP. NOI excludes a number of income and expense categories as detailed in the reconciliation of NOI to net income. A reconciliation of NOI to net income for the three and nine months ended September 30, 2020 and 2019 is as follows (dollars in thousands): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 Net income $ 147,717 $ 279,709 $ 486,592 $ 618,432 Indirect operating expenses, net of corporate income 23,837 20,195 70,043 62,935 Expensed transaction, development and other pursuit costs, net of recoveries 567 175 4,289 2,562 Interest expense, net 53,249 51,493 162,562 149,395 (Gain) loss on extinguishment of debt, net (105) 93 9,333 602 General and administrative expense 13,985 12,769 46,878 45,440 Equity in income of unconsolidated real estate entities (5,083) (1,643) (6,770) (780) Depreciation expense 175,348 165,463 529,508 490,213 Income tax (benefit) expense (27) 11,184 (1,069) 11,178 Gain on sale of communities (31,607) (130,484) (91,338) (165,849) Gain on other real estate transactions, net (129) (73) (328) (374) Gain on for-sale condominiums, net of marketing and administrative costs 646 1,108 (4,162) 2,526 Net operating income from real estate assets sold or held for sale (720) (3,404) (3,572) (16,161) Net operating income $ 377,678 $ 406,585 $ 1,201,966 $ 1,200,119 The following is a summary of NOI from real estate assets sold or held for sale for the periods presented (dollars in thousands): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 Rental income from real estate assets sold or held for sale $ 1,449 $ 6,094 $ 6,159 $ 28,116 Operating expenses from real estate assets sold or held for sale (729) (2,690) (2,587) (11,955) Net operating income from real estate assets sold or held for sale $ 720 $ 3,404 $ 3,572 $ 16,161 The primary performance measure for communities under development or redevelopment depends on the stage of completion. While under development, management monitors actual construction costs against budgeted costs as well as lease-up pace and rent levels compared to budget. The following table provides details of the Company's segment information as of the dates specified (dollars in thousands). The segments are classified based on the individual community's status at January 1, 2020. Segment information for the three and nine months ended September 30, 2020 and 2019 has been adjusted to exclude the real estate assets that were sold from January 1, 2019 through September 30, 2020, or otherwise qualify as held for sale as of September 30, 2020, as described in Note 6, "Real Estate Disposition Activities." For the three months ended For the nine months ended Total NOI Total NOI Gross real estate (1) For the period ended September 30, 2020 Established New England $ 78,057 $ 49,089 $ 239,456 $ 155,604 $ 2,774,519 Metro NY/NJ 112,507 75,193 344,475 236,138 4,303,971 Mid-Atlantic 84,038 56,190 259,086 180,886 3,505,272 Pacific Northwest 27,125 18,578 83,539 59,042 994,486 Northern California 95,234 69,752 300,856 228,047 3,274,052 Southern California 105,964 71,125 327,865 228,181 4,152,209 Expansion Markets 5,633 3,015 17,424 10,004 320,944 Total Established 508,558 342,942 1,572,701 1,097,902 19,325,453 Other Stabilized 35,080 22,834 105,246 69,438 1,595,739 Development / Redevelopment 21,300 11,902 58,403 34,626 2,569,413 Land Held for Development N/A N/A N/A N/A 43,494 Non-allocated (2) 1,017 N/A 2,950 N/A 407,821 Total $ 565,955 $ 377,678 $ 1,739,300 $ 1,201,966 $ 23,941,920 For the period ended September 30, 2019 Established New England $ 81,924 $ 54,244 $ 240,178 $ 158,801 $ 2,742,940 Metro NY/NJ 119,857 82,602 355,990 248,530 4,284,077 Mid-Atlantic 88,829 62,430 262,806 185,431 3,475,939 Pacific Northwest 28,589 20,684 84,615 61,498 988,952 Northern California 103,511 79,076 307,207 235,884 3,258,942 Southern California 113,202 79,357 337,488 239,452 4,119,312 Expansion Markets 5,825 3,261 17,607 10,177 320,114 Total Established 541,737 381,654 1,605,891 1,139,773 19,190,276 Other Stabilized 30,199 20,125 77,749 52,091 1,404,506 Development / Redevelopment 8,352 4,806 15,820 8,255 1,824,012 Land Held for Development N/A N/A N/A N/A 20,095 Non-allocated (2) 1,231 N/A 3,484 N/A 552,179 Total $ 581,519 $ 406,585 $ 1,702,944 $ 1,200,119 $ 22,991,068 __________________________________ (1) Does not include gross real estate either sold or classified as held for sale subsequent to September 30, 2019 of $131,790. (2) Revenue represents third-party management, accounting, and developer fees and miscellaneous income which are not allocated to a reportable segment. Gross real estate includes the for-sale residential condominiums at The Park Loggia, as discussed in Note 6, "Real Estate Disposition Activities."

Stock-Based Compensation Plans

Stock-Based Compensation Plans	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans As part of its long-term compensation plans, the Company has granted stock options, performance awards and restricted stock. Information with respect to performance awards granted is as follows: Performance awards Weighted average grant date fair value per award Outstanding at December 31, 2019 253,432 $ 176.27 Granted (1) 76,458 238.72 Change in awards based on performance (2) 18,112 177.26 Converted to restricted stock (96,317) 177.26 Forfeited (10,488) 188.52 Outstanding at September 30, 2020 241,197 $ 195.22 __________________________________ (1) The amount of restricted stock that ultimately may be earned is based on the total shareholder return metrics related to the Company's common stock for 38,461 performance awards and financial metrics related to operating performance, net asset value and leverage metrics of the Company for 37,997 performance awards. (2) Represents the change in the number of performance awards earned based on performance achievement for the performance period. The Company used a Monte Carlo model to assess the compensation cost associated with the portion of the performance awards granted in 2020 for which achievement will be determined by using total shareholder return measures. The assumptions used are as follows: 2020 Dividend yield 2.8% Estimated volatility over the life of the plan (1) 11.1% - 15.5% Risk free rate 1.45% - 1.62% Estimated performance award value based on total shareholder return measure $254.72 __________________________________ (1) Estimated volatility of the life of the plan is using 50% historical volatility and 50% implied volatility. For the portion of the performance awards granted in 2020 for which achievement will be determined by using financial metrics, the compensation cost was based on a weighted average grant date value of $225.30, and the Company's estimate of corporate achievement for the financial metrics. Information with respect to restricted stock granted is as follows: Restricted stock shares Restricted stock shares weighted average grant date fair value per share Restricted stock shares converted from performance awards Outstanding at December 31, 2019 148,326 $ 181.29 163,111 Granted - restricted stock shares 69,109 221.18 96,317 Vested - restricted stock shares (77,761) 178.32 (109,758) Forfeited (5,637) 195.89 (1,784) Outstanding at September 30, 2020 134,037 $ 202.96 147,886 Total employee stock-based compensation cost recognized in income was $17,385,000 and $20,291,000 for the nine months ended September 30, 2020 and 2019, respectively, and total capitalized stock-based compensation cost was $8,291,000 and $7,622,000 for the nine months ended September 30, 2020 and 2019, respectively. At September 30, 2020, there was a total unrecognized compensation cost of $30,677,000 for unvested restricted stock and performance awards, which does not include forfeitures, and is expected to be recognized over a weighted average period of 1.9 years.

Related Party Arrangements

Related Party Arrangements	9 Months Ended
	Sep. 30, 2020
Related Party Transactions [Abstract]
Related Party Arrangements	Related Party Arrangements Unconsolidated Entities The Company manages unconsolidated real estate entities for which it receives asset management, property management, development and redevelopment fee revenue. From these entities, the Company earned fees of $1,017,000 and $1,231,000 for the three months ended September 30, 2020 and 2019, respectively and $2,950,000 and $3,484,000 for the nine months ended September 30, 2020 and 2019, respectively. In addition, the Company had outstanding receivables associated with its property and construction management role of $5,241,000 and $3,924,000 as of September 30, 2020 and December 31, 2019, respectively. Director Compensation The Company recorded non-employee director compensation expense relating to restricted stock grants and deferred stock units in the amount of $459,000 and $458,000 in the three months ended September 30, 2020 and 2019, respectively, and $1,360,000 and $1,288,000 in the nine months ended September 30, 2020 and 2019, respectively, as a component of general and administrative expense. Deferred compensation relating to these restricted stock grants and deferred stock units to non-employee directors was $996,000 and $594,000 on September 30, 2020 and December 31, 2019, respectively, reported as a component of prepaid expenses and other assets on the accompanying Condensed Consolidated Balance Sheets.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Fair Value	Fair Value Financial Instruments Carried at Fair Value Derivative Financial Instruments The Company uses interest rate swap and interest rate cap agreements to manage its interest rate risk. These instruments are carried at fair value in the Company's financial statements. In adjusting the fair value of its derivative contracts for the effect of counterparty nonperformance risk, the Company has considered the impact of its net position with a given counterparty, as well as any applicable credit enhancements, such as collateral postings, thresholds, mutual puts and guarantees. The Company minimizes its credit risk on these transactions by dealing with major, creditworthy financial institutions which have an A or better credit rating by the Standard & Poor's Ratings Group. As part of its on-going control procedures, the Company monitors the credit ratings of counterparties and the exposure of the Company to any single entity, thus reducing credit risk concentration. The Company believes the likelihood of realizing losses from counterparty nonperformance is remote. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, such as interest rate, term to maturity and volatility, the credit valuation adjustments associated with its derivatives use Level 3 inputs, such as estimates of current credit spreads, to evaluate the likelihood of default by itself and its counterparties. As of September 30, 2020, the Company assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined it is not significant. As a result, the Company has determined that its derivative valuations are classified in Level 2 of the fair value hierarchy. The following table summarizes the consolidated derivative positions at September 30, 2020 (dollars in thousands): Non-designated Cash Flow Notional balance $ 440,097 $ 150,000 Weighted average interest rate (1) 1.7 % N/A Weighted average swapped/capped interest rate 6.5 % 0.7 % Earliest maturity date January 2021 May 2021 Latest maturity date November 2021 May 2021 ____________________________________ (1) For debt hedged by interest rate caps, represents the weighted average interest rate on the hedged debt prior to any impact of the associated interest rate cap. The following activity occurred during the nine months ended September 30, 2020: • The Company settled an aggregate of $600,000,000 of forward interest rate swap agreements, making aggregate payments of $25,135,000. Of the positions settled by the Company, $250,000,000 were forward interest swaps that the Company had entered into during 2020. ◦ In conjunction with the issuance of the Company's $700,000,000 unsecured notes due 2030 in February 2020, the Company settled $350,000,000 of forward interest rate swap agreements designated as cash flow hedges of the interest rate variability on the issuance of the unsecured notes, making a payment of $20,314,000. ◦ In conjunction with the issuance of the Company's $600,000,000 unsecured notes due 2031 in May 2020, the Company settled $250,000,000 of forward interest rate swap agreements designated as cash flow hedges of the interest rate variability on the issuance of the unsecured notes, making a payment of $4,821,000. The Company has deferred these amounts in accumulated other comprehensive loss on the accompanying Condensed Consolidated Balance Sheets, and is recognizing the impact as a component of interest expense, net, over the term of the respective hedged debt. • The Company entered into an additional $150,000,000 of new forward interest rate swap agreements executed to reduce the impact of variability of interest rates on a portion of the Company's expected debt issuance activity in 2021. At the maturity of the remaining outstanding swap agreements, the Company expects to cash settle the contracts and either pay or receive cash for the then current fair value. Assuming that the Company issues the debt as expected, the hedging impact from these positions will then be recognized over the life of the issued debt as a yield adjustment. The Company had three derivatives designated as cash flow hedges and five derivatives not designated as hedges at September 30, 2020. Fair value changes for derivatives not in qualifying hedge relationships for the three and nine months ended September 30, 2020 and 2019 were not material. During the nine months ended September 30, 2020, the Company deferred $17,731,000 of losses for cash flow hedges reported as a component of accumulated other comprehensive loss. The following table summarizes the deferred losses reclassified from accumulated other comprehensive loss as a component of interest expense, net (dollars in thousands): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 Cash flow hedge losses reclassified to earnings $ 2,367 $ 1,746 $ 6,617 $ 4,825 The Company anticipates reclassifying approximately $9,467,000 of net hedging losses from accumulated other comprehensive loss into earnings within the next 12 months as an offset to the hedged item during this period. The Company did not have any derivatives designated as fair value hedges as of September 30, 2020 and 2019. Redeemable Noncontrolling Interests The Company is party to investments in two consolidated ventures, which contain redemption options (the "Puts") that allow joint venture partners of the Company to require the Company to purchase their interests in the investment at a guaranteed minimum amount. The Puts are payable in cash. The Company determines the fair value of the Puts based on unobservable inputs considering the assumptions that market participants would make in pricing the obligations, applying a guaranteed rate of return to the joint venture partners' net capital contribution balances as of period end. Given the significance of the unobservable inputs, the valuations are classified in Level 3 of the fair value hierarchy. The Company issued units of limited partnership interest in a DownREIT which provides the DownREIT limited partners the ability to present all or some of their units for redemption for cash as determined by the partnership agreement. Under the DownREIT agreement, for each limited partnership unit, the limited partner is entitled to receive cash in the amount equal to the fair value of the Company's common stock on or about the date of redemption. In lieu of cash redemption, the Company may elect to exchange such units for an equal number of shares of the Company's common stock. The limited partnership units in the DownREIT are valued using the market price of the Company's common stock, a Level 1 price under the fair value hierarchy. Financial Instruments Not Carried at Fair Value Cash and Cash Equivalents Cash and cash equivalent balances are held with various financial institutions within accounts designed to preserve principal. The Company monitors credit ratings of these financial institutions and the concentration of cash and cash equivalent balances with any one financial institution and believes the likelihood of realizing material losses related to cash and cash equivalent balances is remote. Cash and cash equivalents are carried at their face amounts, which reasonably approximate their fair values and are Level 1 within the fair value hierarchy. Other Financial Instruments Rents and other receivables and prepaid expenses, accounts and construction payable and accrued expenses and other liabilities are carried at their face amounts, which reasonably approximate their fair values. The Company values its unsecured notes using quoted market prices, a Level 1 price within the fair value hierarchy. The Company values its notes payable and outstanding amounts under the Credit Facility and Term Loans using a discounted cash flow analysis on the expected cash flows of each instrument. This analysis reflects the contractual terms of the instrument, including the period to maturity, and uses observable market-based inputs, including interest rate curves. The process also considers credit valuation adjustments to appropriately reflect the Company's nonperformance risk. The Company has concluded that the value of its notes payable and amounts outstanding under its Credit Facility and Term Loans are Level 2 prices as the majority of the inputs used to value its positions fall within Level 2 of the fair value hierarchy. Financial Instruments Measured/Disclosed at Fair Value on a Recurring Basis The following tables summarize the classification between the three levels of the fair value hierarchy of the Company's financial instruments measured/disclosed at fair value on a recurring basis (dollars in thousands): 9/30/2020 Description Total Fair Value Quoted Prices Significant Significant Cash Flow Hedges Interest Rate Swaps - Assets $ 1,413 $ — $ 1,413 $ — DownREIT units (1,120) (1,120) — — Indebtedness Fixed rate unsecured notes (7,269,443) (7,269,443) — — Secured notes and variable rate unsecured indebtedness (1,073,689) — (1,073,689) — Total $ (8,342,839) $ (7,270,563) $ (1,072,276) $ — 12/31/2019 Description Total Fair Value Quoted Prices Significant Significant Cash Flow Hedges Interest Rate Swaps - Assets $ 388 $ — $ 388 $ — Interest Rate Swaps - Liabilities (6,379) — (6,379) — Puts (206) — — (206) DownREIT units (1,573) (1,573) — — Indebtedness Fixed rate unsecured notes (6,197,771) (6,197,771) — — Secured notes and variable rate unsecured indebtedness (1,398,147) — (1,398,147) — Total $ (7,603,688) $ (6,199,344) $ (1,404,138) $ (206)

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2020
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The Company has evaluated subsequent events through the date on which this Form 10-Q was filed, the date on which these financial statements were issued, and identified the items below for discussion. In October 2020, the Company repurchased 219,186 shares of common stock at an average price of $148.17 per share. In October 2020, the Company entered into agreements to sell three wholly-owned operating communities containing an aggregate of 858 apartment homes and net real estate of $126,397,000 as of September 30, 2020, resulting in the communities qualifying as held for sale subsequent to September 30, 2020. The Company expects to complete the sales of these communities in the fourth quarter of 2020. In October 2020, the Company acquired three parcels of land for development for an aggregate investment of $59,145,000. As of November 4, 2020, the Company has $183,000,000 outstanding under its Credit Facility.

Organization, Basis of Presen_2

Organization, Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation AvalonBay Communities, Inc. (the "Company," which term, unless the context otherwise requires, refers to AvalonBay Communities, Inc. together with its subsidiaries), is a Maryland corporation that has elected to be treated as a real estate investment trust ("REIT") for federal income tax purposes under the Internal Revenue Code of 1986 (the "Code"). The Company focuses on the development, redevelopment, acquisition, ownership and operation of multifamily communities in New England, the New York/New Jersey metro area, the Mid-Atlantic, the Pacific Northwest, and Northern and Southern California, as well as in the Company's expansion markets in Southeast Florida and Denver, Colorado (the "Expansion Markets"). At September 30, 2020, the Company owned or held a direct or indirect ownership interest in 275 operating apartment communities containing 80,292 apartment homes in 11 states and the District of Columbia, of which one community containing 344 apartment homes was under redevelopment. In addition, the Company owned or held a direct or indirect ownership interest in 19 communities under development that are expected to contain an aggregate of 6,384 apartment homes when completed, as well as The Park Loggia, which contains 172 for-sale residential condominiums, of which 59 have been sold as of September 30, 2020, and 67,000 square feet of commercial space, of which 64% has been leased as of September 30, 2020. The Company also owned or held a direct or indirect ownership interest in land or rights to land on which the Company expects to develop an additional 27 communities that, if developed as expected, will contain an estimated 9,320 apartment homes. The interim unaudited financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("GAAP") for interim financial information and in conjunction with the rules and regulations of the Securities and Exchange Commission ("SEC"). Certain information and footnote disclosures normally included in financial statements required by GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited financial statements should be read in conjunction with the financial statements and notes included in the Company's 2019 Annual Report on Form 10-K. The results of operations for the three and nine months ended September 30, 2020 are not necessarily indicative of the operating results for the full year. Management believes the disclosures are adequate to ensure the information presented is not misleading. In the opinion of management, all adjustments and eliminations, consisting only of normal, recurring adjustments necessary for a fair presentation of the financial statements for the interim periods, have been included. Capitalized terms used without definition have meanings provided elsewhere in this Form 10-Q.
Earnings per Common Share	Earnings per Common Share Basic earnings per share is computed by dividing net income attributable to common stockholders by the weighted average number of shares outstanding during the period. All outstanding unvested restricted share awards contain rights to non-forfeitable dividends and participate in undistributed earnings with common shareholders and, accordingly, are considered participating securities that are included in the two-class method of computing basic earnings per share ("EPS"). Both the unvested restricted shares and other potentially dilutive common shares, and the related impact to earnings, are considered when calculating earnings per share on a diluted basis. The Company's earnings per common share are determined as follows (dollars in thousands, except per share data): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 Basic and diluted shares outstanding Weighted average common shares - basic 140,271,574 139,340,142 140,366,438 138,931,955 Weighted average DownREIT units outstanding 7,500 7,500 7,500 7,500 Effect of dilutive securities 324,648 505,032 328,865 498,609 Weighted average common shares - diluted 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 $ 279,677 $ 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 140,271,574 139,340,142 140,366,438 138,931,955 Earnings per common share - basic $ 1.05 $ 2.00 $ 3.46 $ 4.44 Calculation of Earnings per Share - diluted Net income attributable to common stockholders $ 147,703 $ 279,677 $ 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 140,603,722 139,852,674 140,702,803 139,438,064 Earnings per common share - diluted $ 1.05 $ 2.00 $ 3.46 $ 4.43 All options to purchase shares of common stock outstanding as of September 30, 2020 and 2019 are included in the computation of diluted earnings per share.
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging ActivitiesThe Company enters into interest rate swap and interest rate cap agreements (collectively, "Hedging Derivatives") for interest rate risk management purposes and in conjunction with certain variable rate secured debt to satisfy lender requirements. The Company does not enter into Hedging Derivative transactions for trading or other speculative purposes. The Company assesses the effectiveness of qualifying cash flow and fair value hedges, both at inception and on an on-going basis. Hedge ineffectiveness is reported as a component of interest expense, net. The fair values of Hedging Derivatives that are in an asset position are recorded in prepaid expenses and other assets. The fair value of Hedging Derivatives that are in a liability position are included in accrued expenses and other liabilities. The Company does not present or disclose the fair value of Hedging Derivatives on a net basis. Fair value changes for derivatives that are not in qualifying hedge relationships are reported as a component of interest expense, net. For the Hedging Derivative positions that the Company has determined qualify as effective cash flow hedges, the Company has recorded the cumulative changes in the fair value of Hedging Derivatives in other comprehensive loss. Amounts recorded in accumulated other comprehensive loss will be reclassified into earnings in the periods in which earnings are affected by the hedged cash flow. The effective portion of the change in fair value of the Hedging Derivatives that the Company has determined qualified as effective fair value hedges is reported as an adjustment to the carrying amount of the corresponding debt being hedged.
Legal and Other Contingencies	Legal and Other Contingencies The Company is involved in various claims and/or administrative proceedings that arise in the ordinary course of its business. While no assurances can be given, the Company does not currently believe that any of these outstanding litigation matters, individually or in the aggregate, will have a material adverse effect on its financial condition or results of operations.
Real Estate, Policy	Acquisitions of Investments in Real Estate The Company accounts for acquisitions of investments in real estate in accordance with the authoritative guidance for the initial measurement, which first requires that the Company determine if the real estate investment is the acquisition of an asset or a business combination. Under either model, the Company must identify and determine the fair value of any assets acquired, liabilities assumed and any noncontrolling interest in the acquiree. Typical assets acquired and liabilities assumed include land, building, furniture, fixtures and equipment, debt and identified intangible assets and liabilities, consisting of the value of above or below market leases and in-place leases. In making estimates of fair values for purposes of allocating purchase price, the Company utilizes various sources, including its own analysis of recently acquired and existing comparable properties in its portfolio and other market data. Consideration for acquisitions is typically in the form of cash unless otherwise disclosed. For a business combination, the Company records the assets acquired and liabilities assumed based on the fair value of each respective item. For an asset acquisition, the allocation of the purchase price is based on the relative fair value of the net assets. The Company expenses all applicable acquisition costs for a business combination and capitalizes all applicable acquisition costs for an asset acquisition. The Company expects that acquisitions of individual operating communities will generally be viewed as asset acquisitions.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. These estimates and assumptions affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the dates of the financial statements and the reported amounts of revenue and expenses during the reporting periods. Actual results could differ from those estimates.
Reclassifications	ReclassificationsCertain reclassifications have been made to amounts in prior years' notes to financial statements to conform to current year presentations as a result of changes in held for sale classification, disposition activity and segment classification.
For-Sale Condominium Inventory	For-Sale Condominium Inventory The Company presents for-sale condominium inventory at historical cost and evaluates the condominium inventory for impairment when potential indicators exist, as further discussed in Note 6, "Real Estate Disposition Activities."
Lessee Considerations	Lessee Considerations The Company assesses whether a contract is or contains a lease based on whether the contract conveys the right to control the use of an identified asset, including specified portions of larger assets, for a period of time in exchange for consideration. The Company’s leases include both fixed and variable lease payments, which are based on an index or rate such as the consumer price index (CPI) or percentage rents based on total sales. Lease payments included in the lease liability include only payments that depend on an index or rate. For leases that have options to extend the term or terminate the lease early, the Company only factored the impact of such options into the lease term if the option was considered reasonably certain to be exercised. The Company determined the discount rate associated with its ground and office leases on a lease by lease basis using the Company’s actual borrowing rates as well as indicative market pricing for longer term rates and taking into consideration the remaining term of each of the lease agreements.
Lessor Considerations	Lessor Considerations The Company evaluates leases in which it is the lessor, which are composed of residential and commercial leases at its apartment communities, and determined these leases to be operating leases. For lease agreements that provide for rent concessions and/or scheduled fixed and determinable rent increases, rental income is recognized on a straight-line basis over the noncancellable term of the lease, which, for residential leases, is generally one year. Some of the Company’s commercial leases have fixed-price renewal options, and the lessee may be able to exercise its renewal option at an amount less than the fair value of the rent at such time. The Company only includes renewal options in the lease term if, at the commencement of the lease, it is reasonably certain that the lessee will exercise this option.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued and Adopted Accounting Standards In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. This ASU requires entities to estimate a lifetime expected credit loss for most financial assets, including (i) trade and other receivables, (ii) other long term financings including available for sale and held-to-maturity debt securities and (iii) loans. Subsequently, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments-Credit Losses, which amends the scope of ASU 2016-13 and clarified that receivables arising from operating leases are not within the scope of the standard and should continue to be accounted for in accordance with the leases standard (Topic 842). The new standard was adopted on January 1, 2020 and does not have a material effect on the Company’s financial position or results of operations.

Organization, Basis of Presen_3

Organization, Basis of Presentation and Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2020
Accounting Policies [Abstract]
Schedule of earnings per common share	The Company's earnings per common share are determined as follows (dollars in thousands, except per share data): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 Basic and diluted shares outstanding Weighted average common shares - basic 140,271,574 139,340,142 140,366,438 138,931,955 Weighted average DownREIT units outstanding 7,500 7,500 7,500 7,500 Effect of dilutive securities 324,648 505,032 328,865 498,609 Weighted average common shares - diluted 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 $ 279,677 $ 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 140,271,574 139,340,142 140,366,438 138,931,955 Earnings per common share - basic $ 1.05 $ 2.00 $ 3.46 $ 4.44 Calculation of Earnings per Share - diluted Net income attributable to common stockholders $ 147,703 $ 279,677 $ 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 140,603,722 139,852,674 140,702,803 139,438,064 Earnings per common share - diluted $ 1.05 $ 2.00 $ 3.46 $ 4.43
Disaggregation of revenue	The following table provides details of the Company’s revenue streams disaggregated by the Company’s reportable operating segments, further discussed in Note 8, “Segment Reporting,” for the three and nine months ended September 30, 2020 and 2019. Segment information for total revenue has been adjusted to exclude the real estate assets that were sold from January 1, 2019 through September 30, 2020, or otherwise qualify as held for sale as of September 30, 2020, as described in Note 6, "Real Estate Disposition Activities" (dollars in thousands): For the three months ended Established Other Development/ Non- Total For the period ended September 30, 2020 Management, development and other fees $ — $ — $ — $ 1,017 $ 1,017 Rental and non-rental related income (2) 1,959 477 337 — 2,773 Total non-lease revenue (3) 1,959 477 337 1,017 3,790 Lease income (4) 506,587 34,333 20,963 — 561,883 Business interruption insurance proceeds 12 270 — — 282 Total revenue $ 508,558 $ 35,080 $ 21,300 $ 1,017 $ 565,955 For the period ended September 30, 2019 Management, development and other fees $ — $ — $ — $ 1,231 $ 1,231 Rental and non-rental related income (2) 1,796 445 133 — 2,374 Total non-lease revenue (3) 1,796 445 133 1,231 3,605 Lease income (4) 539,634 29,754 8,219 — 577,607 Business interruption insurance proceeds 307 — — — 307 Total revenue $ 541,737 $ 30,199 $ 8,352 $ 1,231 $ 581,519 For the nine months ended Established Other Development/ Non- Total For the period ended September 30, 2020 Management, development and other fees $ — $ — $ — $ 2,950 $ 2,950 Rental and non-rental related income (2) 5,416 1,271 884 — 7,571 Total non-lease revenue (3) 5,416 1,271 884 2,950 10,521 Lease income (4) 1,567,170 103,705 57,519 — 1,728,394 Business interruption insurance proceeds 115 270 — — 385 Total revenue $ 1,572,701 $ 105,246 $ 58,403 $ 2,950 $ 1,739,300 For the period ended September 30, 2019 Management, development and other fees $ — $ — $ — $ 3,484 $ 3,484 Rental and non-rental related income (2) 5,753 1,078 224 — 7,055 Total non-lease revenue (3) 5,753 1,078 224 3,484 10,539 Lease income (4) 1,599,224 76,671 15,596 — 1,691,491 Business interruption insurance proceeds 914 — — — 914 Total revenue $ 1,605,891 $ 77,749 $ 15,820 $ 3,484 $ 1,702,944 __________________________________ (1) Revenue represents third-party management, asset management and developer fees and miscellaneous income which are not allocated to a reportable segment. (2) Amounts include revenue streams related to leasing activities that are not considered components of a lease, including but not limited to, apartment hold fees and application fees, as well as revenue streams not related to leasing activities, including but not limited to, vendor revenue sharing, building advertising, vending and dry cleaning revenue. (3) Represents all revenue accounted for under ASU 2014-09. (4) Amounts include all revenue streams derived from residential and commercial rental income and other lease income, which are accounted for under ASC 842.

Mortgage Notes Payable, Unsec_2

Mortgage Notes Payable, Unsecured Notes and Credit Facility (Tables)	9 Months Ended
	Sep. 30, 2020
Debt Disclosure [Abstract]
Summary of company's mortgage notes payable, unsecured notes and Credit Facility excluding mortgage notes secured by communities classified as held for sale	The following amounts and discussion do not include the mortgage notes related to the communities classified as held for sale, if any, as of September 30, 2020 and December 31, 2019, as shown in the accompanying Condensed Consolidated Balance Sheets (dollars in thousands) (see Note 6, "Real Estate Disposition Activities"). 9/30/2020 12/31/2019 Fixed rate unsecured notes (1) $ 6,500,000 $ 5,850,000 Variable rate unsecured notes (1) — 300,000 Term Loans (1) 250,000 250,000 Fixed rate mortgage notes payable - conventional and tax-exempt (2) 409,649 479,221 Variable rate mortgage notes payable - conventional and tax-exempt (2) 471,450 476,150 Total mortgage notes payable and unsecured notes and Term Loans 7,631,099 7,355,371 Credit Facility — — Total mortgage notes payable, unsecured notes, Term Loans and Credit Facility $ 7,631,099 $ 7,355,371 _____________________________________ (1) Balances at September 30, 2020 and December 31, 2019 exclude $10,782 and $8,610, respectively, of debt discount, and $38,968 and $32,742, respectively, of deferred financing costs, as reflected in unsecured notes, net on the accompanying Condensed Consolidated Balance Sheets. (2) Balances at September 30, 2020 and December 31, 2019 exclude $14,636 and $14,464, respectively, of debt discount, and $3,067 and $3,265, respectively, of deferred financing costs, as reflected in mortgage notes payable, net on the accompanying Condensed Consolidated Balance Sheets.
Scheduled payments and maturities of mortgage notes payable and unsecured notes outstanding	Scheduled payments and maturities of secured notes payable and unsecured notes outstanding at September 30, 2020 are as follows (dollars in thousands): Year Secured notes Secured notes maturities Unsecured notes and Term Loans maturities Stated interest rate of unsecured notes and Term Loans 2020 $ 1,285 $ — $ — N/A 2021 9,304 27,844 — N/A 2022 9,918 — 450,000 2.950 % 100,000 LIBOR + 0.90% 2023 10,739 — 350,000 4.200 % 250,000 2.850 % 2024 11,677 — 300,000 3.500 % 150,000 LIBOR + 0.85% 2025 12,408 — 525,000 3.450 % 300,000 3.500 % 2026 13,445 — 475,000 2.950 % 300,000 2.900 % 2027 15,080 236,100 400,000 3.350 % 2028 20,607 — 450,000 3.200 % 2029 11,742 66,250 450,000 3.300 % Thereafter 189,362 245,338 700,000 2.300 % 600,000 2.450 % 350,000 3.900 % 300,000 4.150 % 300,000 4.350 % $ 305,567 $ 575,532 $ 6,750,000

Equity (Tables)

Equity (Tables)	9 Months Ended
	Sep. 30, 2020
Stockholders' Equity Note [Abstract]
Summary of changes in equity	The following summarizes the changes in equity for the nine months ended September 30, 2020 (dollars in thousands): Common Additional Accumulated Accumulated Total AvalonBay stockholder's equity Noncontrolling interests Total Balance at December 31, 2019 $ 1,406 $ 10,736,733 $ 282,913 $ (31,503) $ 10,989,549 $ 649 $ 10,990,198 Net income attributable to common stockholders — — 167,971 — 167,971 — 167,971 Loss on cash flow hedges, net — — — (17,603) (17,603) — (17,603) Cash flow hedge losses reclassified to earnings — — — 1,949 1,949 — 1,949 Change in redemption value of redeemable noncontrolling interest — — 471 — 471 — 471 Noncontrolling interest distribution and income allocation — — — — — (35) (35) Dividends declared to common stockholders ($1.59 per share) — — (224,083) — (224,083) — (224,083) Issuance of common stock, net of withholdings 1 (12,492) (1,616) — (14,107) — (14,107) Amortization of deferred compensation — 7,781 — — 7,781 — 7,781 Balance at March 31, 2020 $ 1,407 $ 10,732,022 $ 225,656 $ (47,157) $ 10,911,928 $ 614 $ 10,912,542 Net income attributable to common stockholders — — 170,828 — 170,828 — 170,828 Loss on cash flow hedges, net — — — (1,461) (1,461) — (1,461) Cash flow hedge losses reclassified to earnings — — — 2,301 2,301 — 2,301 Change in redemption value of redeemable noncontrolling interest — — (146) — (146) — (146) Noncontrolling interest distribution and income allocation — — — — — 1 1 Dividends declared to common stockholders ($1.59 per share) — — (224,172) — (224,172) — (224,172) Issuance of common stock, net of withholdings — 1,050 138 — 1,188 — 1,188 Amortization of deferred compensation — 9,724 — — 9,724 — 9,724 Balance at June 30, 2020 $ 1,407 $ 10,742,796 $ 172,304 $ (46,317) $ 10,870,190 $ 615 $ 10,870,805 Net income attributable to common stockholders — — 147,703 — 147,703 — 147,703 Gain on cash flow hedges, net — — — 1,333 1,333 — 1,333 Cash flow hedge losses reclassified to earnings — — — 2,367 2,367 — 2,367 Change in redemption value of redeemable noncontrolling interest — — 62 — 62 — 62 Noncontrolling interest distribution and income allocation — — — — — (17) (17) Dividends declared to common stockholders ($1.59 per share) — — (222,694) — (222,694) — (222,694) Issuance of common stock, net of withholdings — 105 — — 105 — 105 Repurchase of common stock, including repurchase costs (9) (69,779) (67,670) — (137,458) — (137,458) Amortization of deferred compensation — 8,036 — — 8,036 — 8,036 Balance at September 30, 2020 $ 1,398 $ 10,681,158 $ 29,705 $ (42,617) $ 10,669,644 $ 598 $ 10,670,242 The following summarizes the changes in equity for the nine months ended September 30, 2019 (dollars in thousands): Common Additional Accumulated Accumulated Total AvalonBay stockholder's equity Noncontrolling interests Total Balance at December 31, 2018 $ 1,385 $ 10,306,588 $ 350,777 $ (26,144) $ 10,632,606 $ — $ 10,632,606 Net income attributable to common stockholders — — 170,366 — 170,366 — 170,366 Loss on cash flow hedges, net — — — (7,231) (7,231) — (7,231) Cash flow hedge losses reclassified to earnings — — — 1,468 1,468 — 1,468 Change in redemption value of redeemable noncontrolling interest — — (224) — (224) — (224) Dividends declared to common stockholders ($1.52 per share) — — (212,166) — (212,166) — (212,166) Issuance of common stock, net of withholdings 9 143,202 (1,892) — 141,319 — 141,319 Amortization of deferred compensation — 7,861 — — 7,861 — 7,861 Balance at March 31, 2019 $ 1,394 $ 10,457,651 $ 306,861 $ (31,907) $ 10,733,999 $ — $ 10,733,999 Net income attributable to common stockholders — — 168,281 — 168,281 — 168,281 Loss on cash flow hedges, net — — — (2,888) (2,888) — (2,888) Cash flow hedge losses reclassified to earnings — — — 1,611 1,611 — 1,611 Change in redemption value of redeemable noncontrolling interest — — (45) — (45) — (45) Noncontrolling interests income allocation — — — — — 530 530 Dividends declared to common stockholders ($1.52 per share) — — (212,549) — (212,549) — (212,549) Issuance of common stock, net of withholdings 3 50,803 — — 50,806 — 50,806 Amortization of deferred compensation — 10,785 — — 10,785 — 10,785 Balance at June 30, 2019 $ 1,397 $ 10,519,239 $ 262,548 $ (33,184) $ 10,750,000 $ 530 $ 10,750,530 Net income attributable to common stockholders — — 279,677 — 279,677 — 279,677 Loss on cash flow hedges, net — — — (13,644) (13,644) — (13,644) Cash flow hedge losses reclassified to earnings — — — 1,746 1,746 — 1,746 Change in redemption value of redeemable noncontrolling interest — — (113) — (113) — (113) Noncontrolling interests income allocation — — — — — 118 118 Dividends declared to common stockholders ($1.52 per share) — — (212,526) — (212,526) — (212,526) Issuance of common stock, net of withholdings — (454) (263) — (717) — (717) Amortization of deferred compensation — 10,002 — — 10,002 — 10,002 Balance at September 30, 2019 $ 1,397 $ 10,528,787 $ 329,323 $ (45,082) $ 10,814,425 $ 648 $ 10,815,073

Investments in Real Estate En_2

Investments in Real Estate Entities (Tables)	9 Months Ended
	Sep. 30, 2020
Equity Method Investments and Joint Ventures [Abstract]
Summary of financial information of equity method investments	The following is a combined summary of the financial position of the entities accounted for using the equity method discussed above as of the dates presented, including development joint ventures started and unconsolidated communities sold during the respective periods (dollars in thousands): 9/30/2020 12/31/2019 (unaudited) Assets: Real estate, net $ 1,222,762 $ 1,204,470 Other assets 265,048 196,488 Total assets $ 1,487,810 $ 1,400,958 Liabilities and partners' capital: Mortgage notes payable, net (1) $ 749,555 $ 782,257 Other liabilities 158,875 157,379 Partners' capital 579,380 461,322 Total liabilities and partners' capital $ 1,487,810 $ 1,400,958 _________________________________ (1) The Company has not guaranteed the outstanding debt, nor does the Company have any obligation to fund this debt should the unconsolidated entity be unable to do so. The following is a combined summary of the operating results of the entities accounted for using the equity method discussed above for the periods presented (dollars in thousands): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 (unaudited) (unaudited) Rental and other income $ 28,800 $ 37,382 $ 92,299 $ 108,635 Operating and other expenses (12,782) (14,535) (37,034) (42,624) Gain on sale of communities 18,408 — 18,448 — Interest expense, net (8,024) (8,385) (24,133) (25,482) Depreciation expense (8,704) (9,324) (26,106) (49,366) Net income (loss) $ 17,698 $ 5,138 $ 23,474 $ (8,837) Company's share of net income (loss) (1) $ 5,611 $ 2,175 $ 8,357 $ 2,377 Amortization of excess investment and other (528) (532) (1,587) (1,597) Equity in income from unconsolidated real estate investments $ 5,083 $ 1,643 $ 6,770 $ 780

Segment Reporting (Tables)

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2020
Segment Reporting [Abstract]
Schedule of reconciliation of NOI to net income	A reconciliation of NOI to net income for the three and nine months ended September 30, 2020 and 2019 is as follows (dollars in thousands): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 Net income $ 147,717 $ 279,709 $ 486,592 $ 618,432 Indirect operating expenses, net of corporate income 23,837 20,195 70,043 62,935 Expensed transaction, development and other pursuit costs, net of recoveries 567 175 4,289 2,562 Interest expense, net 53,249 51,493 162,562 149,395 (Gain) loss on extinguishment of debt, net (105) 93 9,333 602 General and administrative expense 13,985 12,769 46,878 45,440 Equity in income of unconsolidated real estate entities (5,083) (1,643) (6,770) (780) Depreciation expense 175,348 165,463 529,508 490,213 Income tax (benefit) expense (27) 11,184 (1,069) 11,178 Gain on sale of communities (31,607) (130,484) (91,338) (165,849) Gain on other real estate transactions, net (129) (73) (328) (374) Gain on for-sale condominiums, net of marketing and administrative costs 646 1,108 (4,162) 2,526 Net operating income from real estate assets sold or held for sale (720) (3,404) (3,572) (16,161) Net operating income $ 377,678 $ 406,585 $ 1,201,966 $ 1,200,119
Schedule of net operating income from real estate assets sold or held for sale, not classified as discontinued operations	The following is a summary of NOI from real estate assets sold or held for sale for the periods presented (dollars in thousands): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 Rental income from real estate assets sold or held for sale $ 1,449 $ 6,094 $ 6,159 $ 28,116 Operating expenses from real estate assets sold or held for sale (729) (2,690) (2,587) (11,955) Net operating income from real estate assets sold or held for sale $ 720 $ 3,404 $ 3,572 $ 16,161
Schedule of details of segment information	For the three months ended For the nine months ended Total NOI Total NOI Gross real estate (1) For the period ended September 30, 2020 Established New England $ 78,057 $ 49,089 $ 239,456 $ 155,604 $ 2,774,519 Metro NY/NJ 112,507 75,193 344,475 236,138 4,303,971 Mid-Atlantic 84,038 56,190 259,086 180,886 3,505,272 Pacific Northwest 27,125 18,578 83,539 59,042 994,486 Northern California 95,234 69,752 300,856 228,047 3,274,052 Southern California 105,964 71,125 327,865 228,181 4,152,209 Expansion Markets 5,633 3,015 17,424 10,004 320,944 Total Established 508,558 342,942 1,572,701 1,097,902 19,325,453 Other Stabilized 35,080 22,834 105,246 69,438 1,595,739 Development / Redevelopment 21,300 11,902 58,403 34,626 2,569,413 Land Held for Development N/A N/A N/A N/A 43,494 Non-allocated (2) 1,017 N/A 2,950 N/A 407,821 Total $ 565,955 $ 377,678 $ 1,739,300 $ 1,201,966 $ 23,941,920 For the period ended September 30, 2019 Established New England $ 81,924 $ 54,244 $ 240,178 $ 158,801 $ 2,742,940 Metro NY/NJ 119,857 82,602 355,990 248,530 4,284,077 Mid-Atlantic 88,829 62,430 262,806 185,431 3,475,939 Pacific Northwest 28,589 20,684 84,615 61,498 988,952 Northern California 103,511 79,076 307,207 235,884 3,258,942 Southern California 113,202 79,357 337,488 239,452 4,119,312 Expansion Markets 5,825 3,261 17,607 10,177 320,114 Total Established 541,737 381,654 1,605,891 1,139,773 19,190,276 Other Stabilized 30,199 20,125 77,749 52,091 1,404,506 Development / Redevelopment 8,352 4,806 15,820 8,255 1,824,012 Land Held for Development N/A N/A N/A N/A 20,095 Non-allocated (2) 1,231 N/A 3,484 N/A 552,179 Total $ 581,519 $ 406,585 $ 1,702,944 $ 1,200,119 $ 22,991,068 __________________________________ (1) Does not include gross real estate either sold or classified as held for sale subsequent to September 30, 2019 of $131,790. (2) Revenue represents third-party management, accounting, and developer fees and miscellaneous income which are not allocated to a reportable segment. Gross real estate includes the for-sale residential condominiums at The Park Loggia, as discussed in Note 6, "Real Estate Disposition Activities."

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2020
Share-based Payment Arrangement [Abstract]
Schedule of nonvested performance awards granted	Information with respect to performance awards granted is as follows: Performance awards Weighted average grant date fair value per award Outstanding at December 31, 2019 253,432 $ 176.27 Granted (1) 76,458 238.72 Change in awards based on performance (2) 18,112 177.26 Converted to restricted stock (96,317) 177.26 Forfeited (10,488) 188.52 Outstanding at September 30, 2020 241,197 $ 195.22 __________________________________ (1) The amount of restricted stock that ultimately may be earned is based on the total shareholder return metrics related to the Company's common stock for 38,461 performance awards and financial metrics related to operating performance, net asset value and leverage metrics of the Company for 37,997 performance awards. (2) Represents the change in the number of performance awards earned based on performance achievement for the performance period.
Summary of valuation options	The Company used a Monte Carlo model to assess the compensation cost associated with the portion of the performance awards granted in 2020 for which achievement will be determined by using total shareholder return measures. The assumptions used are as follows: 2020 Dividend yield 2.8% Estimated volatility over the life of the plan (1) 11.1% - 15.5% Risk free rate 1.45% - 1.62% Estimated performance award value based on total shareholder return measure $254.72 __________________________________ (1) Estimated volatility of the life of the plan is using 50% historical volatility and 50% implied volatility.
Schedule of restricted stock granted	Information with respect to restricted stock granted is as follows: Restricted stock shares Restricted stock shares weighted average grant date fair value per share Restricted stock shares converted from performance awards Outstanding at December 31, 2019 148,326 $ 181.29 163,111 Granted - restricted stock shares 69,109 221.18 96,317 Vested - restricted stock shares (77,761) 178.32 (109,758) Forfeited (5,637) 195.89 (1,784) Outstanding at September 30, 2020 134,037 $ 202.96 147,886

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Schedule of summary of consolidated Hedging Derivatives, excluding derivatives executed to hedge debt on communities classified as held for sale	The following table summarizes the consolidated derivative positions at September 30, 2020 (dollars in thousands): Non-designated Cash Flow Notional balance $ 440,097 $ 150,000 Weighted average interest rate (1) 1.7 % N/A Weighted average swapped/capped interest rate 6.5 % 0.7 % Earliest maturity date January 2021 May 2021 Latest maturity date November 2021 May 2021 ____________________________________ (1) For debt hedged by interest rate caps, represents the weighted average interest rate on the hedged debt prior to any impact of the associated interest rate cap.
Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss)	The following table summarizes the deferred losses reclassified from accumulated other comprehensive loss as a component of interest expense, net (dollars in thousands): For the three months ended For the nine months ended 9/30/2020 9/30/2019 9/30/2020 9/30/2019 Cash flow hedge losses reclassified to earnings $ 2,367 $ 1,746 $ 6,617 $ 4,825
Schedule of summary of classification between the three levels of the fair value hierarchy of the Company's financial instruments measured at fair value on a recurring basis	The following tables summarize the classification between the three levels of the fair value hierarchy of the Company's financial instruments measured/disclosed at fair value on a recurring basis (dollars in thousands): 9/30/2020 Description Total Fair Value Quoted Prices Significant Significant Cash Flow Hedges Interest Rate Swaps - Assets $ 1,413 $ — $ 1,413 $ — DownREIT units (1,120) (1,120) — — Indebtedness Fixed rate unsecured notes (7,269,443) (7,269,443) — — Secured notes and variable rate unsecured indebtedness (1,073,689) — (1,073,689) — Total $ (8,342,839) $ (7,270,563) $ (1,072,276) $ — 12/31/2019 Description Total Fair Value Quoted Prices Significant Significant Cash Flow Hedges Interest Rate Swaps - Assets $ 388 $ — $ 388 $ — Interest Rate Swaps - Liabilities (6,379) — (6,379) — Puts (206) — — (206) DownREIT units (1,573) (1,573) — — Indebtedness Fixed rate unsecured notes (6,197,771) (6,197,771) — — Secured notes and variable rate unsecured indebtedness (1,398,147) — (1,398,147) — Total $ (7,603,688) $ (6,199,344) $ (1,404,138) $ (206)

Organization, Basis of Presen_4

Organization, Basis of Presentation and Significant Accounting Policies (Details) ft² in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020USD ($)residential_condominiumft²homecommunitystate	Sep. 30, 2020USD ($)ft²homeresidential_condominiumcommunitystate
Real Estate Properties [Line Items]
Number of operating apartment communities | community	275	275
Number of apartment homes included in operating apartment communities owned	80,292	80,292
Number of states where operating apartment communities owned are located | state	11	11
Number of Communities with Apartments under Reconstruction	1	1
Number of Apartment Homes under Reconstruction	344	344
Number of owned communities under construction | community	19	19
Expected number of apartment homes under construction	6,384	6,384
Number of Residential Condominium Units Sold | residential_condominium	7	59
Communities under development rights | community	27	27
Estimated number of apartment homes in communities to be developed	9,320	9,320
Accounts Receivable, Credit Loss Expense (Reversal) | $	$ 18,755	$ 43,034
The Park Loggia [Member]
Real Estate Properties [Line Items]
Number Of Residential Condominium Units	172	172
Commercial Square Feet | ft²	67	67
Percent of Commercial Square Feet Leased	64.00%	64.00%

Organization, Basis of Presen_5

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			$ 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			$ 3.46	$ 4.43

Organization, Basis of Presen_6

Organization, Basis of Presentation and Significant Accounting Policies (Details 3) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Management, development and other fees	$ 1,017	$ 1,231	$ 2,950	$ 3,484
Rental and other income	566,387	586,382	1,742,509	1,727,576
Total revenue	567,404	587,613	1,745,459	1,731,060
Operating Segments | Established Communities
Disaggregation of Revenue [Line Items]
Total revenue	508,558	541,737	1,572,701	1,605,891
Operating Segments | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Total revenue	35,080	30,199	105,246	77,749
Non-allocated
Disaggregation of Revenue [Line Items]
Total revenue	1,017	1,231	2,950	3,484
Continuing Operations
Disaggregation of Revenue [Line Items]
Management, development and other fees	3,790	3,605	10,521	10,539
Rental and other income	561,883	577,607	1,728,394	1,691,491
Gain on Business Interruption Insurance Recovery	282	307	385	914
Total revenue	565,955	581,519	1,739,300	1,702,944
Continuing Operations | Management, development and other fees
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,017	1,231	2,950	3,484
Continuing Operations | Rental and non-rental related income
Disaggregation of Revenue [Line Items]
Management, development and other fees	2,773	2,374	7,571	7,055
Continuing Operations | Operating Segments | Established Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,959	1,796	5,416	5,753
Rental and other income	506,587	539,634	1,567,170	1,599,224
Gain on Business Interruption Insurance Recovery	12	307	115	914
Total revenue	508,558	541,737	1,572,701	1,605,891
Continuing Operations | Operating Segments | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	477	445	1,271	1,078
Rental and other income	34,333	29,754	103,705	76,671
Gain on Business Interruption Insurance Recovery	270	0	270	0
Total revenue	35,080	30,199	105,246	77,749
Continuing Operations | Operating Segments | Development/ Redevelopment Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	337	133	884	224
Rental and other income	20,963	8,219	57,519	15,596
Gain on Business Interruption Insurance Recovery	0	0	0	0
Total revenue	21,300	8,352	58,403	15,820
Continuing Operations | Operating Segments | Management, development and other fees | Established Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	0	0	0	0
Continuing Operations | Operating Segments | Management, development and other fees | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	0	0	0	0
Continuing Operations | Operating Segments | Management, development and other fees | Development/ Redevelopment Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	0	0	0	0
Continuing Operations | Operating Segments | Rental and non-rental related income | Established Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,959	1,796	5,416	5,753
Continuing Operations | Operating Segments | Rental and non-rental related income | Other Stabilized Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	477	445	1,271	1,078
Continuing Operations | Operating Segments | Rental and non-rental related income | Development/ Redevelopment Communities
Disaggregation of Revenue [Line Items]
Management, development and other fees	337	133	884	224
Continuing Operations | Non-allocated
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,017	1,231	2,950	3,484
Rental and other income	0	0	0	0
Gain on Business Interruption Insurance Recovery	0	0	0	0
Total revenue	1,017	1,231	2,950	3,484
Continuing Operations | Non-allocated | Management, development and other fees
Disaggregation of Revenue [Line Items]
Management, development and other fees	1,017	1,231	2,950	3,484
Continuing Operations | Non-allocated | Rental and non-rental related income
Disaggregation of Revenue [Line Items]
Management, development and other fees	$ 0	$ 0	$ 0	$ 0

Interest Capitalized (Details)

Interest Capitalized (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Interest Capitalized
Capitalized interest during the development and redevelopment of real estate assets	$ 11,221	$ 15,443	$ 33,738	$ 50,159

Mortgage Notes Payable, Unsec_3

Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($)	Sep. 30, 2020	Feb. 29, 2020	Dec. 31, 2019
Notes Payable, Unsecured Notes and Credit Facility
Total mortgage notes payable and unsecured notes and Term Loans	$ 7,631,099,000		$ 7,355,371,000
Credit Facility	0		0
Total mortgage notes payable, unsecured notes, Term Loans and Credit Facility	7,631,099,000		7,355,371,000
Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Long-term Debt, Percentage Bearing Fixed Interest, Amount	6,500,000,000		5,850,000,000
Variable rate notes	0		300,000,000
Total mortgage notes payable and unsecured notes and Term Loans	6,750,000,000
Amount of debt discount	10,782,000		8,610,000
Amount of deferred financing costs, net	38,968,000		32,742,000
Term Loans
Notes Payable, Unsecured Notes and Credit Facility
Variable rate notes	250,000,000		250,000,000
Secured notes
Notes Payable, Unsecured Notes and Credit Facility
Long-term Debt, Percentage Bearing Fixed Interest, Amount	409,649,000		479,221,000
Variable rate notes	471,450,000		476,150,000
Total mortgage notes payable and unsecured notes and Term Loans	575,532,000
Amount of debt discount	14,636,000		14,464,000
Amount of deferred financing costs, net	3,067,000		3,265,000
Unsecured Notes 2.30 Percent [Member]
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Face Amount		$ 700,000,000
Line of Credit [Member]
Notes Payable, Unsecured Notes and Credit Facility
Credit Facility	$ 0		$ 0

Mortgage Notes Payable, Unsec_4

Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details 2) - USD ($)	1 Months Ended				3 Months Ended		9 Months Ended
	Aug. 31, 2020	May 31, 2020	Mar. 31, 2020	Feb. 29, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Notes Payable, Unsecured Notes and Credit Facility
Repayments of Unsecured Debt							$ 958,681,000	$ 0
Gain (Loss) on Extinguishment of Debt					$ 105,000	$ (93,000)	(9,333,000)	$ (602,000)
Credit Facility					0		0		$ 0
Net carrying value of apartment communities and improved land parcels securing debt					1,455,524,000		1,455,524,000
Unsecured Notes 2.45 Percent [Member]
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Face Amount		$ 600,000,000
Proceeds from Issuance of Debt		593,430,000
Secured Debt [Member]
Notes Payable, Unsecured Notes and Credit Facility
Long-term Debt, Percentage Bearing Fixed Interest, Amount					409,649,000		409,649,000		479,221,000
Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Long-term Debt, Percentage Bearing Fixed Interest, Amount					6,500,000,000		6,500,000,000		5,850,000,000
Unsecured Notes 2.30 Percent [Member]
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Face Amount				$ 700,000,000
Proceeds from Issuance of Debt				$ 694,701,000
Unsecured Notes 2.30 Percent [Member] | Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Interest Rate, Stated Percentage				2.30%
Floating Rate Unsecured Notes 300 Million [Member] | Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Repayments of Unsecured Debt		300,000,000
Gain (Loss) on Extinguishment of Debt		$ 268,000
Notes Payable 3.625 Maturities 2020 and 2021 [Member] | Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Gain (Loss) on Extinguishment of Debt			$ 9,170,000
Unsecured Notes 2.45 Percent [Member] | Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Interest Rate, Stated Percentage		2.45%
Notes Payable Maturities 2021 [Member] | Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Interest Rate, Stated Percentage			3.95%
Repayments of Unsecured Debt			$ 250,000,000
Notes Payable Maturities 2020 [Member]
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Interest Rate, Stated Percentage	4.18%			3.08%
Line of Credit [Member]
Notes Payable, Unsecured Notes and Credit Facility
Available borrowing capacity					1,750,000,000		$ 1,750,000,000
Annual facility fee, percentage							0.125%
Annual facility fee							$ 2,188,000
Credit Facility					0		0		0
Outstanding balance of letters of credit					$ 3,752,000		$ 3,752,000		11,488,000
Line of Credit [Member] | LIBOR
Notes Payable, Unsecured Notes and Credit Facility
Debt instrument, basis spread on variable rate (as a percent)							0.775%
Current interest rate (as a percent)					0.92%		0.92%
Other Letter of Credit [Member]
Notes Payable, Unsecured Notes and Credit Facility
Outstanding balance of letters of credit					$ 31,822,000		$ 31,822,000		$ 24,939,000
Fixed Rate Mortgage Notes Payable [Member]
Notes Payable, Unsecured Notes and Credit Facility
Weighted average interest rate, debt (as a percent)					3.80%		3.80%		3.90%
Notes Payable Maturities 2027
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Interest Rate, Stated Percentage				2.38%
Notes Payable Maturities 2027 | Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Interest Rate, Stated Percentage					3.35%		3.35%
Notes Payable 3.625 Maturities 2020 [Member] | Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Interest Rate, Stated Percentage			3.625%
Repayments of Unsecured Debt			$ 400,000,000
Variable Rate Mortgage Notes Payable Unsecured Term Loan and Credit Facility [Member]
Notes Payable, Unsecured Notes and Credit Facility
Weighted average interest rate, debt (as a percent)					1.70%		1.70%		3.20%
Avalon San Bruno III [Member] | Notes Payable Maturities 2027 | Secured Debt [Member]
Notes Payable, Unsecured Notes and Credit Facility
Long-term Debt, Percentage Bearing Fixed Interest, Amount				$ 51,000,000
Avalon Hoboken [Member] | Notes Payable Maturities 2020, Fixed Rate [Member] | Secured Debt [Member]
Notes Payable, Unsecured Notes and Credit Facility
Repayments of Secured Debt	$ 67,904,000

Mortgage Notes Payable, Unsec_5

Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details 3) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Aug. 31, 2020	Mar. 31, 2020	Feb. 29, 2020	Dec. 31, 2019
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 7,631,099				$ 7,355,371
Notes Payable Maturities 2020 [Member]
Notes Payable, Unsecured Notes and Credit Facility
Stated interest rate of unsecured notes (as a percent)		4.18%		3.08%
Notes Payable Maturities 2027
Notes Payable, Unsecured Notes and Credit Facility
Stated interest rate of unsecured notes (as a percent)				2.38%
Secured notes
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	305,567
Mortgage notes payable and unsecured notes	575,532
Secured notes | Notes Payable Maturities 2020 [Member]
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	1,285
Mortgage notes payable and unsecured notes	0
Secured notes | Notes Payable Maturities 2021 [Member]
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	9,304
Mortgage notes payable and unsecured notes	27,844
Secured notes | Notes payable maturing in 2022
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	9,918
Secured notes | Notes Payable Maturities 2023
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	10,739
Secured notes | Notes Payable Maturities 2024
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	11,677
Secured notes | Notes Payable Maturities 2025
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	12,408
Secured notes | Notes Payable Maturities 2026
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	13,445
Secured notes | Notes Payable Maturities 2027
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	15,080
Mortgage notes payable and unsecured notes	236,100
Secured notes | Notes Payable Maturities 2028
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	20,607
Secured notes | Notes Payable Maturities 2029 [Member]
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	11,742
Mortgage notes payable and unsecured notes	66,250
Secured notes | Notes Payable Maturities Thereafter
Notes Payable, Unsecured Notes and Credit Facility
Secured notes payments	189,362
Mortgage notes payable and unsecured notes	245,338
Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	6,750,000
Unsecured notes | Notes Payable Maturities 2021 [Member]
Notes Payable, Unsecured Notes and Credit Facility
Stated interest rate of unsecured notes (as a percent)			3.95%
Unsecured notes | Notes payable maturing in 2022
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 450,000
Stated interest rate of unsecured notes (as a percent)	2.95%
Unsecured notes | Variable Rate Unsecured Term Loan $100 Million
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 100,000
Unsecured notes | Variable Rate Unsecured Term Loan $100 Million | LIBOR
Notes Payable, Unsecured Notes and Credit Facility
Debt instrument, basis spread on variable rate (as a percent)	0.90%
Unsecured notes | Notes payable 4.200 Maturities 2023
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 350,000
Stated interest rate of unsecured notes (as a percent)	4.20%
Unsecured notes | Notes Payable 2.850 Maturities 2023
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 250,000
Stated interest rate of unsecured notes (as a percent)	2.85%
Unsecured notes | Notes Payable Maturities 2024
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 300,000
Stated interest rate of unsecured notes (as a percent)	3.50%
Unsecured notes | Variable Rate Unsecured Term Loan $150 Million
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 150,000
Unsecured notes | Variable Rate Unsecured Term Loan $150 Million | LIBOR
Notes Payable, Unsecured Notes and Credit Facility
Debt instrument, basis spread on variable rate (as a percent)	0.85%
Unsecured notes | Notes Payable 3.450 Maturities 2025
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 525,000
Stated interest rate of unsecured notes (as a percent)	3.45%
Unsecured notes | Notes Payable 3.500 Maturities 2025
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 300,000
Stated interest rate of unsecured notes (as a percent)	3.50%
Unsecured notes | Notes Payable 2.950 Maturities 2026
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 475,000
Stated interest rate of unsecured notes (as a percent)	2.95%
Unsecured notes | Notes Payable 2.900 Maturities 2026
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 300,000
Stated interest rate of unsecured notes (as a percent)	2.90%
Unsecured notes | Notes Payable Maturities 2027
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 400,000
Stated interest rate of unsecured notes (as a percent)	3.35%
Unsecured notes | Notes Payable Maturities 2028
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 450,000
Stated interest rate of unsecured notes (as a percent)	3.20%
Unsecured notes | Notes Payable Maturities 2029 [Member]
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 450,000
Stated interest rate of unsecured notes (as a percent)	3.30%
Unsecured notes | Notes Payable Maturities 2030 [Member]
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 700,000
Stated interest rate of unsecured notes (as a percent)	2.30%
Unsecured notes | Notes Payable Maturities 2031 [Member]
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 600,000
Stated interest rate of unsecured notes (as a percent)	2.45%
Unsecured notes | Notes Payable Maturities 2046
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 350,000
Stated interest rate of unsecured notes (as a percent)	3.90%
Unsecured notes | Notes Payable Maturities 2047
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 300,000
Stated interest rate of unsecured notes (as a percent)	4.15%
Unsecured notes | Notes Payable Maturities 2048
Notes Payable, Unsecured Notes and Credit Facility
Mortgage notes payable and unsecured notes	$ 300,000
Stated interest rate of unsecured notes (as a percent)	4.35%

Equity (Details)

Equity (Details) - 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
Class of Stock [Line Items]
Issuance of common stock, net							$ 1,599	$ 207,789
Changes in equity
Beginning Balance	$ 10,870,805	$ 10,912,542	$ 10,990,198	$ 10,750,530	$ 10,733,999	$ 10,632,606	10,990,198	10,632,606
Net income attributable to common stockholders	147,703	170,828	167,971	279,677	168,281	170,366	486,502	618,324
Gain (loss) on cash flow hedges	1,333	(1,461)	(17,603)	(13,644)	(2,888)	(7,231)	(17,731)	(23,763)
Cash flow hedge losses reclassified to earnings	2,367	2,301	1,949	1,746	1,611	1,468	6,617	4,825
Change in redemption value of redeemable noncontrolling interest	62	(146)	471	(113)	(45)	(224)
Noncontrolling interest distribution and income allocation	(17)	1	(35)	118	530
Dividends, Common Stock	(222,694)	(224,172)	(224,083)	(212,526)	(212,549)	(212,166)
Issuance of common stock, net of withholdings	105	1,188	(14,107)	(717)	50,806	141,319
Stock Repurchased During Period, Value	(137,458)
Amortization of deferred compensation	8,036	9,724	7,781	10,002	10,785	7,861
Ending Balance	$ 10,670,242	$ 10,870,805	$ 10,912,542	$ 10,815,073	$ 10,750,530	$ 10,733,999	10,670,242	10,815,073
Dividends declared to common stockholders (in dollars per share)	$ 1.59	$ 1.59	$ 1.59	$ 1.52	$ 1.52	$ 1.52
Common stock
Changes in equity
Beginning Balance	$ 1,407	$ 1,407	$ 1,406	$ 1,397	$ 1,394	$ 1,385	1,406	1,385
Issuance of common stock, net of withholdings		0	1		3	9
Stock Repurchased During Period, Value	(9)
Ending Balance	1,398	1,407	1,407	1,397	1,397	1,394	1,398	1,397
Additional paid-in capital
Changes in equity
Beginning Balance	10,742,796	10,732,022	10,736,733	10,519,239	10,457,651	10,306,588	10,736,733	10,306,588
Issuance of common stock, net of withholdings	105	1,050	(12,492)	(454)	50,803	143,202
Stock Repurchased During Period, Value	(69,779)
Amortization of deferred compensation	8,036	9,724	7,781	10,002	10,785	7,861
Ending Balance	10,681,158	10,742,796	10,732,022	10,528,787	10,519,239	10,457,651	10,681,158	10,528,787
Accumulated earnings less dividends
Changes in equity
Beginning Balance	172,304	225,656	282,913	262,548	306,861	350,777	282,913	350,777
Net income attributable to common stockholders	147,703	170,828	167,971	279,677	168,281	170,366
Change in redemption value of redeemable noncontrolling interest	62	(146)	471	(113)	(45)	(224)	387	(382)
Dividends, Common Stock	(222,694)	(224,172)	(224,083)	(212,526)	(212,549)	(212,166)
Issuance of common stock, net of withholdings		138	(1,616)	(263)	0	(1,892)
Stock Repurchased During Period, Value	(67,670)
Ending Balance	29,705	172,304	225,656	329,323	262,548	306,861	29,705	329,323
Accumulated other comprehensive loss
Changes in equity
Beginning Balance	(46,317)	(47,157)	(31,503)	(33,184)	(31,907)	(26,144)	(31,503)	(26,144)
Gain (loss) on cash flow hedges	1,333	(1,461)	(17,603)	(13,644)	(2,888)	(7,231)
Cash flow hedge losses reclassified to earnings	2,367	2,301	1,949	1,746	1,611	1,468
Ending Balance	(42,617)	(46,317)	(47,157)	(45,082)	(33,184)	(31,907)	(42,617)	(45,082)
Parent [Member]
Changes in equity
Beginning Balance	10,870,190	10,911,928	10,989,549	10,750,000	10,733,999	10,632,606	10,989,549	10,632,606
Net income attributable to common stockholders	147,703	170,828	167,971	279,677	168,281	170,366
Gain (loss) on cash flow hedges	1,333	(1,461)	(17,603)	(13,644)	(2,888)	(7,231)
Cash flow hedge losses reclassified to earnings	2,367	2,301	1,949	1,746	1,611	1,468
Change in redemption value of redeemable noncontrolling interest	62	(146)	471	(113)	(45)	(224)
Dividends, Common Stock	(222,694)	(224,172)	(224,083)	(212,526)	(212,549)	(212,166)
Issuance of common stock, net of withholdings	105	1,188	(14,107)	(717)	50,806	141,319
Stock Repurchased During Period, Value	(137,458)
Amortization of deferred compensation	8,036	9,724	7,781	10,002	10,785	7,861
Ending Balance	10,669,644	10,870,190	10,911,928	10,814,425	10,750,000	$ 10,733,999	10,669,644	10,814,425
Noncontrolling Interest [Member]
Changes in equity
Beginning Balance	615	614	649	530			649
Noncontrolling interest distribution and income allocation	(17)	1	(35)	118	530
Ending Balance	$ 598	$ 615	$ 614	$ 648	$ 530		598	$ 648
Continuous Equity Program CEP V [Member]
Class of Stock [Line Items]
Issuance of common stock, net							$ 0

Equity (Details 2)

Equity (Details 2) - USD ($)	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Jul. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common stock, shares authorized (in shares)	280,000,000			280,000,000
Preferred stock, shares authorized (in shares)	50,000,000			50,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	1,902
Common stock issued through the dividend reinvestment plan (in shares)	1,967	1,594
Number of shares of stock grants withheld (in shares)	73,103	83,602
Stock Issued During Period, Shares, Employee Stock Purchase Plans	8,685
Stock issued during period, shares, share-based compensation, forfeited (in shares)	7,421
Treasury Stock, Shares, Acquired	912,733
Treasury Stock Acquired, Average Cost Per Share	$ 150.58
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 362,560,000
Issuance of common stock, net	1,599,000	$ 207,789,000
2020 Stock Repurchase Program [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount			$ 500,000,000
Amended 2005 Stock Repurchase Program [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount			$ 500,000,000
Continuous Equity Program CEP V [Member]
Class of Stock [Line Items]
Maximum value of shares of common stock that can be sold (in dollars)	1,000,000,000
Common stock value, remaining to be authorized under continuous equity program	752,878,000
Issuance of common stock, net	$ 0
Maximum | Continuous Equity Program CEP V [Member]
Class of Stock [Line Items]
Percentage of compensation received by sales agent	1.50%
Restricted Stock and Restricted Stock Converted From Performance Shares
Class of Stock [Line Items]
Equity instruments granted (in shares)	165,426	150,359

Investments in Real Estate En_3

Investments in Real Estate Entities - Narrative of Investment in Real Estate Entities (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)entity	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)entity	Sep. 30, 2019USD ($)
Equity method investment
Expensed transaction, development and other pursuit costs, net of recoveries | $	$ 567	$ 175	$ 4,289	$ 2,562
Unconsolidated real estate entities
Equity method investment
Number of unconsolidated real estate entities | entity	8		8
Minimum | Unconsolidated real estate entities
Equity method investment
Ownership percentage	20.00%		20.00%
Maximum | Unconsolidated real estate entities
Equity method investment
Ownership percentage	50.00%		50.00%

Investments in Real Estate En_4

Investments in Real Estate Entities - Financial Position and Operating Results (Details) ft² in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)homeft²	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)homeft²	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
ASSETS
Real estate, net	$ 18,297,701,000		$ 18,297,701,000		$ 18,432,989,000
Total assets	19,144,611,000		19,144,611,000		19,121,051,000
LIABILITIES AND EQUITY
Mortgage notes payable, net	863,396,000		863,396,000		937,642,000
Partners' capital	10,669,644,000		10,669,644,000		10,989,549,000
Total liabilities and equity	19,144,611,000		19,144,611,000		19,121,051,000
Combined summary of the operating results of the accounted for using the equity method
Rental and other income	567,404,000	$ 587,613,000	1,745,459,000	$ 1,731,060,000
Operating and other expenses	(455,887,000)	(427,812,000)	(1,362,534,000)	(1,265,927,000)
Gain on sale of communities	31,607,000	130,484,000	91,338,000	165,849,000
Interest expense, net	(53,249,000)	(51,493,000)	(162,562,000)	(149,395,000)
Depreciation expense	(175,348,000)	(165,463,000)	(529,508,000)	(490,213,000)
Net income	147,717,000	279,709,000	486,592,000	618,432,000
Equity Method Investment, Net Income (Loss), Portion Attributable To Parent	5,611,000	2,175,000	8,357,000	2,377,000
Equity Method Investments, Amortization Of Excess Investment And Other	(528,000)	(532,000)	(1,587,000)	(1,597,000)
Equity in income of unconsolidated real estate entities	$ 5,083,000	1,643,000	$ 6,770,000	780,000
Avalon Venice on Rose [Member]
Combined summary of the operating results of the accounted for using the equity method
Commercial Square Feet | ft²	9		9
Avalon Venice on Rose [Member] | Notes Payable Maturities 2020 [Member] | Secured Debt [Member]
Combined summary of the operating results of the accounted for using the equity method
Repayments of Secured Debt			$ 27,117,000
US Fund [Member]
Combined summary of the operating results of the accounted for using the equity method
Proceeds from Sale of Real Estate			$ 65,000,000
US Fund [Member] | Avalon Venice on Rose [Member]
Combined summary of the operating results of the accounted for using the equity method
Number Of Apartment Homes Sold | home			70
Equity Method Investment, Realized Gain (Loss) on Disposal			$ 5,157,000
AVA Arts District [Member]
Combined summary of the operating results of the accounted for using the equity method
Number Of operating apartment communities owned | home	475		475
Ownership percentage	25.00%		25.00%
Equity method investments	$ 14,800,000		$ 14,800,000
Long-term Construction Loan	$ 165,600,000		$ 165,600,000
Real Estate Investments, Percent Of Development Funded By Borrowings	60.00%		60.00%
Proceeds from construction loans			$ 0
AVA Arts District [Member] | Maximum
Combined summary of the operating results of the accounted for using the equity method
Equity method investments	$ 27,600,000		$ 27,600,000
AVA Arts District [Member] | Joint Venture Partner [Member]
Combined summary of the operating results of the accounted for using the equity method
Ownership percentage	75.00%		75.00%
Equity Method Investment, Nonconsolidated Investee or Group of Investees
ASSETS
Real estate, net	$ 1,222,762,000		$ 1,222,762,000		1,204,470,000
Other assets	265,048,000		265,048,000		196,488,000
Total assets	1,487,810,000		1,487,810,000		1,400,958,000
LIABILITIES AND EQUITY
Mortgage notes payable, net	749,555,000		749,555,000		782,257,000
Other liabilities	158,875,000		158,875,000		157,379,000
Partners' capital	579,380,000		579,380,000		461,322,000
Total liabilities and equity	1,487,810,000		1,487,810,000		$ 1,400,958,000
Combined summary of the operating results of the accounted for using the equity method
Rental and other income	28,800,000	37,382,000	92,299,000	108,635,000
Operating and other expenses	(12,782,000)	(14,535,000)	(37,034,000)	(42,624,000)
Gain on sale of communities	18,408,000	0	18,448,000	0
Interest expense, net	(8,024,000)	(8,385,000)	(24,133,000)	(25,482,000)
Depreciation expense	(8,704,000)	(9,324,000)	(26,106,000)	(49,366,000)
Net income	$ 17,698,000	$ 5,138,000	$ 23,474,000	$ (8,837,000)

Investments in Real Estate En_5

Investments in Real Estate Entities - Expensed Acquisition, Development and Other Pursuit Costs and Impairment of Long-Lived Assets & Casualty Gains and Losses (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Equity method investment
Expensed transaction, development and other pursuit costs, net of recoveries	$ 567,000	$ 175,000	$ 4,289,000	$ 2,562,000
Impairment of investment in unconsolidated entities	0	0	0	0
Land Parcel [Member]
Equity method investment
Casualty and impairment (gain) loss, net	0	$ 0	0	$ 0
The Park Loggia [Member]
Equity method investment
Casualty and impairment (gain) loss, net	$ 0		$ 0

Real Estate Disposition Activ_2

Real Estate Disposition Activities (Details) ft² in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2020USD ($)residential_condominiumft²homecommunity	Jun. 30, 2020USD ($)home	Mar. 31, 2020USD ($)home	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)ft²residential_condominiumcommunityhome	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Summary of income from discontinued operations
Gain on sale of communities	$ 31,607,000			$ 130,484,000	$ 91,338,000	$ 165,849,000
Number Of Communities Held For Sale | community	0				0
Number of Residential Condominium Units Sold | residential_condominium	7				59
Gain (Loss) on Sale of Other Investments					$ 8,174,000	0
Other Selling, General and Administrative Expense	$ 1,373,000			$ 1,108,000	4,012,000	$ 2,526,000
For-sale condominium inventory	$ 298,429,000				298,429,000		$ 457,809,000
Avalon Shelton [Member]
Summary of income from discontinued operations
Number Of Apartment Homes Sold | home			250
Proceeds from Sale of Real Estate			$ 64,750,000
Gain on sale of communities			$ 24,413,000
Avalon Tinton Falls [Member]
Summary of income from discontinued operations
Number Of Apartment Homes Sold | home		216
Proceeds from Sale of Real Estate		$ 64,900,000
Gain on sale of communities		$ 35,297,000
Avalon Towers [Member]
Summary of income from discontinued operations
Number Of Apartment Homes Sold | home	109
Proceeds from Sale of Real Estate	$ 54,000,000
Gain on sale of communities	31,603,000
The Park Loggia [Member]
Summary of income from discontinued operations
Proceeds from Sale of Real Estate	$ 15,699,000				$ 182,512,000
Number Of Residential Condominium Units | home	172				172
Commercial Square Feet | ft²	67				67
Gain (Loss) on Sale of Other Investments	$ 727,000				$ 8,174,000

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020USD ($)communitypropertyLease	Sep. 30, 2019USD ($)	Sep. 30, 2020USD ($)communitypropertyLease	Sep. 30, 2019USD ($)	Dec. 31, 2019USD ($)
Lessee, Lease, Description [Line Items]
Number Of Office Leases | Lease	15		15
Operating lease assets	$ 135,885		$ 135,885		$ 103,063
Operating lease obligation	162,683		162,683		120,261
Operating Lease, Expense	3,958	$ 3,618	12,115	$ 10,723
Finance lease asset	21,738		21,738		21,898
Finance lease obligation	$ 20,176		$ 20,176		$ 20,207
Properties on Land Subject to Land Leases
Lessee, Lease, Description [Line Items]
Number Of operating apartment communities owned | community	11		11
Number of operating apartment communities under construction | community	1		1
Number of commercial properties owned | property	2		2
Assets Held under Operating Leases [Member]
Lessee, Lease, Description [Line Items]
Number Of operating apartment communities owned | community	10		10
Assets Held under Finance Leases [Member]
Lessee, Lease, Description [Line Items]
Number Of operating apartment communities owned | community	1		1
Number Of Finance Leases For Parking Garages Adjacent To Communities | Lease	2		2

Segment Reporting (Details)

Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Reconciliation of NOI to net income
Net income	$ 147,717	$ 279,709	$ 486,592	$ 618,432
Indirect operating expenses, net of corporate income	23,837	20,195	70,043	62,935
Expensed transaction, development and other pursuit costs, net of recoveries	567	175	4,289	2,562
Interest expense, net	53,249	51,493	162,562	149,395
(Gain) loss on extinguishment of debt, net	(105)	93	9,333	602
General and administrative expense	13,985	12,769	46,878	45,440
Equity in income of unconsolidated real estate entities	(5,083)	(1,643)	(6,770)	(780)
Depreciation expense	175,348	165,463	529,508	490,213
Income tax (benefit) expense	(27)	11,184	(1,069)	11,178
Gain on sale of communities	(31,607)	(130,484)	(91,338)	(165,849)
Gain on other real estate transactions, net	(129)	(73)	(328)	(374)
Gain on for-sale condominiums, net of marketing and administrative costs	646	1,108	(4,162)	2,526
Net operating income from real estate assets sold or held for sale	(720)	(3,404)	(3,572)	(16,161)
Net operating income	$ 377,678	$ 406,585	$ 1,201,966	$ 1,200,119

Segment Reporting (Details 2)

Segment Reporting (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting [Abstract]
Rental income from real estate assets sold or held for sale	$ 1,449	$ 6,094	$ 6,159	$ 28,116
Operating expenses from real estate assets sold or held for sale	(729)	(2,690)	(2,587)	(11,955)
Net operating income from real estate assets sold or held for sale	$ 720	$ 3,404	$ 3,572	$ 16,161

Segment Reporting (Details 3)

Segment Reporting (Details 3) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting
Total revenue	$ 567,404	$ 587,613	$ 1,745,459	$ 1,731,060
NOI	377,678	406,585	1,201,966	1,200,119
Gross real estate	23,941,920	22,991,068	23,941,920	22,991,068
Operating Segments | Established
Segment Reporting
Total revenue	508,558	541,737	1,572,701	1,605,891
NOI	342,942	381,654	1,097,902	1,139,773
Gross real estate	19,325,453	19,190,276	19,325,453	19,190,276
Operating Segments | Established | New England
Segment Reporting
Total revenue	78,057	81,924	239,456	240,178
NOI	49,089	54,244	155,604	158,801
Gross real estate	2,774,519	2,742,940	2,774,519	2,742,940
Operating Segments | Established | Metro NY/NJ
Segment Reporting
Total revenue	112,507	119,857	344,475	355,990
NOI	75,193	82,602	236,138	248,530
Gross real estate	4,303,971	4,284,077	4,303,971	4,284,077
Operating Segments | Established | Mid-Atlantic
Segment Reporting
Total revenue	84,038	88,829	259,086	262,806
NOI	56,190	62,430	180,886	185,431
Gross real estate	3,505,272	3,475,939	3,505,272	3,475,939
Operating Segments | Established | Pacific Northwest
Segment Reporting
Total revenue	27,125	28,589	83,539	84,615
NOI	18,578	20,684	59,042	61,498
Gross real estate	994,486	988,952	994,486	988,952
Operating Segments | Established | Northern California
Segment Reporting
Total revenue	95,234	103,511	300,856	307,207
NOI	69,752	79,076	228,047	235,884
Gross real estate	3,274,052	3,258,942	3,274,052	3,258,942
Operating Segments | Established | Southern California
Segment Reporting
Total revenue	105,964	113,202	327,865	337,488
NOI	71,125	79,357	228,181	239,452
Gross real estate	4,152,209	4,119,312	4,152,209	4,119,312
Operating Segments | Established | Expansion Markets [Member]
Segment Reporting
Total revenue	5,633	5,825	17,424	17,607
NOI	3,015	3,261	10,004	10,177
Gross real estate	320,944	320,114	320,944	320,114
Operating Segments | Other Stabilized
Segment Reporting
Total revenue	35,080	30,199	105,246	77,749
NOI	22,834	20,125	69,438	52,091
Gross real estate	1,595,739	1,404,506	1,595,739	1,404,506
Operating Segments | Development / Redevelopment
Segment Reporting
Total revenue	21,300	8,352	58,403	15,820
NOI	11,902	4,806	34,626	8,255
Gross real estate	2,569,413	1,824,012	2,569,413	1,824,012
Operating Segments | Disposals [Member]
Segment Reporting
Gross real estate		131,790		131,790
Land Held for Future Development
Segment Reporting
Gross real estate	43,494	20,095	43,494	20,095
Non-allocated
Segment Reporting
Total revenue	1,017	1,231	2,950	3,484
Gross real estate	407,821	552,179	407,821	552,179
Continuing Operations
Segment Reporting
Total revenue	565,955	581,519	1,739,300	1,702,944
Continuing Operations | Operating Segments | Established
Segment Reporting
Total revenue	508,558	541,737	1,572,701	1,605,891
Continuing Operations | Operating Segments | Other Stabilized
Segment Reporting
Total revenue	35,080	30,199	105,246	77,749
Continuing Operations | Non-allocated
Segment Reporting
Total revenue	$ 1,017	$ 1,231	$ 2,950	$ 3,484

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans (Details 2) - Performance Shares	9 Months Ended
	Sep. 30, 2020$ / sharesshares
Performance awards
Equity instruments outstanding at the beginning of the period (in shares)	253,432
Equity instruments granted (in shares)	76,458
Change in awards based on performance (in shares)	18,112
Converted to restricted stock (in shares)	(96,317)
Forfeited (in shares)	(10,488)
Equity instruments outstanding at the end of the period (in shares)	241,197
Weighted average grant date fair value per award
Equity instruments outstanding at the beginning of the period (in dollars per share) | $ / shares	$ 176.27
Grant date fair value per share (in dollars per share) | $ / shares	238.72
Change in awards based on performance (in dollars per share) | $ / shares	177.26
Converted to restricted stock (in dollars per share) | $ / shares	177.26
Forfeited (in dollars per share) | $ / shares	188.52
Equity instruments outstanding at the end of the period (in dollars per share) | $ / shares	$ 195.22
Grants in period based on total shareholder metrics	38,461
Grants in period based on financial metrics	37,997

Stock-Based Compensation Plan_3

Stock-Based Compensation Plans Stock-Based Compensation Plans (Details 3) - Performance Shares	9 Months Ended
	Sep. 30, 2020$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	2.80%
Estimated volatility, Minimum (as a percent)	11.10%
Estimated volatility, Maximum (as a percent)	15.50%
Risk-free interest rate, minimum (as a percent)	1.45%
Risk-free interest rate, maximum (as a percent)	1.62%
Average estimated fair value (in dollars per share)	$ 254.72
Historical volatility (as a percent)	50.00%
Implied volatility (as a percent)	50.00%

Stock-Based Compensation Plan_4

Stock-Based Compensation Plans Stock-Based Compensation Plans (Details 4) - $ / shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Restricted stock
Restricted stock shares
Equity instruments outstanding at the beginning of the period (in shares)	148,326
Equity instruments granted (in shares)	69,109	77,287
Vested (in shares)	(77,761)
Forfeited (in shares)	(5,637)
Equity instruments outstanding at the end of the period (in shares)	134,037
Restricted stock shares weighted average grant date fair value per share
Equity instruments outstanding at the beginning of the period (in dollars per share)	$ 181.29
Grant date fair value per share (in dollars per share)	221.18
Vested (in dollars per share)	178.32
Forfeited (in dollars per share)	195.89
Equity instruments outstanding at the end of the period (in dollars per share)	$ 202.96
Restricted Stock Converted From Performance Shares
Restricted stock shares
Equity instruments outstanding at the beginning of the period (in shares)	163,111
Equity instruments granted (in shares)	96,317	73,072
Vested (in shares)	(109,758)
Forfeited (in shares)	(1,784)
Equity instruments outstanding at the end of the period (in shares)	147,886

Stock-Based Compensation Plan_5

Stock-Based Compensation Plans (Details 5) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Additional disclosures
Stock-based compensation expense	$ 17,385	$ 20,291
Capitalized stock-based compensation cost	$ 8,291	$ 7,622
Performance Shares
Additional disclosures
Grant date value (in dollars per share)	$ 225.30
Restricted stock and restricted stock units
Additional disclosures
Unrecognized compensation cost for unvested restricted stock	$ 30,677
Weighted average period for recognition of unrecognized compensation cost	1 year 10 months 24 days

Related Party Arrangements (Det

Related Party Arrangements (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Related Party Arrangements
Management, development and other fees	$ 1,017	$ 1,231	$ 2,950	$ 3,484
Compensation expense			17,385	20,291
Unconsolidated real estate entities
Related Party Arrangements
Outstanding receivables	5,241		5,241		$ 3,924
Non Employee Director | Restricted stock and deferred stock awards
Related Party Arrangements
Compensation expense	459	$ 458	1,360	$ 1,288
Amount of deferred compensation	$ 996		$ 996		$ 594

Fair Value (Details)

Fair Value (Details)	3 Months Ended						9 Months Ended
	Sep. 30, 2020USD ($)derivative	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Sep. 30, 2020USD ($)venturederivative	Sep. 30, 2019USD ($)	May 31, 2020USD ($)	Feb. 29, 2020USD ($)
Derivative instruments and Hedging Activities
Derivative, Notional Amounts Settled During Period		$ 250,000,000	$ 350,000,000				$ 600,000,000
Payments for (Proceeds from) Hedge, Financing Activities		4,821,000	20,314,000				25,135,000	$ 12,309,000
Gain (loss) on cash flow hedges	$ 1,333,000	$ (1,461,000)	$ (17,603,000)	$ (13,644,000)	$ (2,888,000)	$ (7,231,000)	$ (17,731,000)	$ (23,763,000)
Cash Flow Hedges
Derivative instruments and Hedging Activities
Number of derivative instruments held | derivative	3						3
Interest Rate Swap | Cash Flow Hedges
Derivative instruments and Hedging Activities
Derivative, Notional Amounts Entered into During Period							$ 150,000,000
Derivative, Notional Amount	$ 150,000,000						$ 150,000,000
Put Option
Derivative instruments and Hedging Activities
Number of ventures in which entity is required to purchase interest in investment at guaranteed minimum amount | venture							2
Reclassification out of Accumulated Other Comprehensive Income
Derivative instruments and Hedging Activities
Estimated hedging losses to be reclassified from accumulated other comprehensive loss into earnings within the next twelve months							$ 9,467,000
Not Designated as Hedging Instrument
Derivative instruments and Hedging Activities
Number of derivative instruments held | derivative	5						5
Not Designated as Hedging Instrument | Interest Rate Cap
Derivative instruments and Hedging Activities
Derivative, Notional Amount	$ 440,097,000						$ 440,097,000
Unsecured Notes 2.45 Percent [Member]
Derivative instruments and Hedging Activities
Debt Instrument, Face Amount									$ 600,000,000
Unsecured Notes 2.30 Percent [Member]
Derivative instruments and Hedging Activities
Debt Instrument, Face Amount										$ 700,000,000

Fair Value Fair Value (Details

Fair Value Fair Value (Details 2)	Sep. 30, 2020USD ($)
Not Designated as Hedging Instrument | Interest Rate Cap
Derivative instruments and Hedging Activities
Derivative, Notional Amount	$ 440,097,000
Derivative weighted average interest rate	1.70%
Derivative, average cap interest rate	6.50%
Cash Flow Hedges | Interest Rate Swap
Derivative instruments and Hedging Activities
Derivative, Notional Amount	$ 150,000,000
Derivative, average cap interest rate	0.70%

Fair Value (Details 3)

Fair Value (Details 3) - USD ($) $ 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
Fair Value Disclosures [Abstract]
Cash flow hedge losses reclassified to earnings	$ (2,367)	$ (2,301)	$ (1,949)	$ (1,746)	$ (1,611)	$ (1,468)	$ (6,617)	$ (4,825)

Fair Value (Details 4)

Fair Value (Details 4) - Recurring basis - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Estimate of Fair Value Measurement
Financial Instruments Measured/Discussed at Fair Value
DownREIT units	$ (1,120)	$ (1,573)
Total	(8,342,839)	(7,603,688)
Estimate of Fair Value Measurement | Unsecured notes
Financial Instruments Measured/Discussed at Fair Value
Indebtedness	(7,269,443)	(6,197,771)
Estimate of Fair Value Measurement | Secured Debt and Variable Rate Unsecured Indebtedness
Financial Instruments Measured/Discussed at Fair Value
Indebtedness	(1,073,689)	(1,398,147)
Estimate of Fair Value Measurement | Interest Rate Swap | Cash Flow Hedges
Financial Instruments Measured/Discussed at Fair Value
Derivative assets	1,413	388
Derivative liability		(6,379)
Estimate of Fair Value Measurement | Put Option
Financial Instruments Measured/Discussed at Fair Value
Fair value of remaining outstanding Puts		(206)
Fair Value, Inputs, Level 1
Financial Instruments Measured/Discussed at Fair Value
DownREIT units	(1,120)	(1,573)
Total	(7,270,563)	(6,199,344)
Fair Value, Inputs, Level 1 | Unsecured notes
Financial Instruments Measured/Discussed at Fair Value
Indebtedness	(7,269,443)	(6,197,771)
Fair Value, Inputs, Level 2
Financial Instruments Measured/Discussed at Fair Value
Total	(1,072,276)	(1,404,138)
Fair Value, Inputs, Level 2 | Secured Debt and Variable Rate Unsecured Indebtedness
Financial Instruments Measured/Discussed at Fair Value
Indebtedness	(1,073,689)	(1,398,147)
Fair Value, Inputs, Level 2 | Interest Rate Swap | Cash Flow Hedges
Financial Instruments Measured/Discussed at Fair Value
Derivative assets	1,413	388
Derivative liability		(6,379)
Fair Value, Inputs, Level 3
Financial Instruments Measured/Discussed at Fair Value
Total	$ 0	(206)
Fair Value, Inputs, Level 3 | Put Option
Financial Instruments Measured/Discussed at Fair Value
Fair value of remaining outstanding Puts		$ (206)

Subsequent Events (Details)

Subsequent Events (Details)	1 Months Ended	9 Months Ended
	Oct. 31, 2020USD ($)land_parcelhomecommunity$ / sharesshares	Sep. 30, 2020USD ($)community$ / sharesshares	Nov. 04, 2020USD ($)	Dec. 31, 2019USD ($)
Subsequent Event [Line Items]
Treasury Stock, Shares, Acquired | shares		912,733
Treasury Stock Acquired, Average Cost Per Share | $ / shares		$ 150.58
Number Of Communities Held For Sale | community		0
Credit Facility		$ 0		$ 0
Line of Credit [Member]
Subsequent Event [Line Items]
Credit Facility		$ 0		$ 0
Subsequent Event [Member]
Subsequent Event [Line Items]
Treasury Stock, Shares, Acquired | shares	219,186
Treasury Stock Acquired, Average Cost Per Share | $ / shares	$ 148.17
Number Of Communities Held For Sale | community	3
Number of Land Parcels Acquired | land_parcel	3
Payments to Acquire Land	$ 59,145,000
Subsequent Event [Member] | Line of Credit [Member]
Subsequent Event [Line Items]
Credit Facility			$ 183,000,000
Subsequent Event [Member] | Subsequent Event Dispositions [Member]
Subsequent Event [Line Items]
Number of Apartment Homes Held For Sale | home	858
Real Estate Investments, Net	$ 126,397,000