AvalonBay Communities (AVB) 10-Q5 Nov 132013 Q3 Quarterly reportFinancial data

Company Profile

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
Document and Entity Information	Sep. 30, 2013	Oct. 31, 2013
Document and Entity Information	'	'
Entity Registrant Name	'AVALONBAY COMMUNITIES INC	'
Entity Central Index Key	'0000915912	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Amendment Flag	'false	'
Current Fiscal Year End Date	'--12-31	'
Entity Current Reporting Status	'Yes	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	129,413,103
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2013	Dec. 31, 2012
Real estate:	'	'
Land	$3,302,403,000	$1,424,797,000
Buildings and improvements	11,116,909,000	6,934,099,000
Furniture, fixtures and equipment	333,638,000	251,537,000
Total Capitalized Cost	14,752,950,000	8,610,433,000
Less accumulated depreciation	-2,445,294,000	-1,988,764,000
Net operating real estate	12,307,656,000	6,621,669,000
Construction in progress, including land	1,418,836,000	802,857,000
Land held for development	282,285,000	316,037,000
Operating real estate assets held for sale, net	275,874,000	274,556,000
Total real estate, net	14,284,651,000	8,015,119,000
Cash and cash equivalents	112,910,000	2,733,618,000
Cash in escrow	98,429,000	49,950,000
Resident security deposits	27,868,000	24,748,000
Investments in unconsolidated real estate entities	347,386,000	129,352,000
Deferred financing costs, net	39,085,000	38,700,000
Deferred development costs	33,799,000	24,665,000
Prepaid expenses and other assets	200,979,000	143,926,000
Total assets	15,145,107,000	11,160,078,000
LIABILITIES AND EQUITY	'	'
Unsecured notes, net	2,245,191,000	1,945,798,000
Mortgage notes payable	3,852,441,000	1,905,235,000
Dividends payable	138,459,000	110,966,000
Payables for construction	84,027,000	52,903,000
Accrued expenses and other liabilities	254,144,000	217,259,000
Accrued interest payable	23,965,000	33,056,000
Resident security deposits	47,020,000	37,691,000
Liabilities related to real estate assets held for sale	8,275,000	9,350,000
Total liabilities	6,653,522,000	4,312,258,000
Redeemable noncontrolling interests	18,255,000	7,027,000
Equity:	'	'
Preferred stock, $0.01 par value; $25 liquidation preference; 50,000,000 shares authorized at both September 30, 2013 and December 31, 2012; zero shares issued and outstanding at September 30, 2013 and December 31, 2012, respectively	'	'
Common stock, $0.01 par value; 280,000,000 shares authorized at September 30, 2013 and 140,000,000 shares authorized at December 31, 2012; 129,402,556 and 114,403,472 shares issued and outstanding at September 30, 2013 and December 31, 2012, respectively	1,294,000	1,144,000
Additional paid-in capital	8,976,780,000	7,086,407,000
Accumulated earnings less dividends	-458,229,000	-142,329,000
Accumulated other comprehensive loss	-50,094,000	-108,007,000
Total equity	8,469,751,000	6,837,215,000
Noncontrolling interest	3,579,000	3,578,000
Total equity	8,473,330,000	6,840,793,000
Total liabilities and equity	$15,145,107,000	$11,160,078,000

CONDENSED_CONSOLIDATED_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
CONDENSED CONSOLIDATED BALANCE SHEETS	'	'
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	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, shares authorized	280,000,000	140,000,000
Common stock, shares issued	129,402,556	114,403,472
Common stock, shares outstanding	129,402,556	114,403,472

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenue:	'	'	'	'
Rental and other income	$390,113	$258,788	$1,072,273	$742,254
Management, development and other fees	3,014	2,533	8,198	7,852
Total revenue	393,127	261,321	1,080,471	750,106
Expenses:	'	'	'	'
Operating expenses, excluding property taxes	97,650	67,471	258,605	196,325
Property taxes	42,678	25,475	116,515	73,171
Interest expense, net	43,945	33,985	127,772	100,804
Loss on interest rate contract	53,484	'	51,000	'
Loss on extinguishment of debt, net	'	'	'	1,179
Depreciation expense	160,682	62,750	457,837	183,688
General and administrative expense	9,878	8,372	31,262	26,398
Expensed acquisition, development and other pursuit costs	2,176	608	46,041	1,749
Total expenses	410,493	198,661	1,089,032	583,314
Equity in income (loss) of unconsolidated entities	3,260	5,553	-16,244	9,801
Gain on sale of land	'	'	240	280
Gain on acquisition of unconsolidated real estate entity	'	14,194	'	14,194
(Loss) income from continuing operations	-14,106	82,407	-24,565	191,067
Discontinued operations:	'	'	'	'
Income from discontinued operations	3,221	4,340	7,073	15,062
Gain on sale of real estate assets	'	'	118,173	95,049
Total discontinued operations	3,221	4,340	125,246	110,111
Net (loss) income	-10,885	86,747	100,681	301,178
Net loss attributable to noncontrolling interests	170	97	248	334
Net (loss) income attributable to common stockholders	-10,715	86,844	100,929	301,512
Other comprehensive income:	'	'	'	'
Unrealized loss on cash flow hedges	'	-6,977	'	-23,767
Cash flow hedge losses reclassified to earnings	54,948	'	57,913	'
Comprehensive income	$44,233	$79,867	$158,842	$277,745
Earnings per common share - basic:	'	'	'	'
(Loss) income from continuing operations attributable to common stockholders (in dollars per share)	($0.11)	$0.85	($0.19)	$1.99
Discontinued operations attributable to common stockholders (in dollars per share)	$0.03	$0.04	$0.99	$1.15
Net (loss) income attributable to common stockholders (in dollars per share)	($0.08)	$0.89	$0.80	$3.14
Earnings per common share - diluted:	'	'	'	'
(Loss) income from continuing operations attributable to common stockholders (in dollars per share)	($0.11)	$0.85	($0.19)	$1.99
Discontinued operations attributable to common stockholders (in dollars per share)	$0.03	$0.04	$0.99	$1.14
Net (loss) income attributable to common stockholders (in dollars per share)	($0.08)	$0.89	$0.80	$3.13
Dividends per common share: (in dollars per share)	$1.07	$0.97	$3.21	$2.91

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:	'	'
Net income	$100,681	$301,178
Adjustments to reconcile net income to cash provided by operating activities:	'	'
Depreciation expense	457,837	183,688
Depreciation expense from discontinued operations	10,727	10,641
Amortization of deferred financing costs and debt (premium) discount	-15,831	4,122
Amortization of stock-based compensation	8,720	8,548
Equity in (income) loss of, and return on, unconsolidated entities and noncontrolling interests, net of eliminations	45,215	-7,484
Cash flow hedge losses reclassified to earnings	57,913	'
Loss on extinguishment of debt, net	'	1,781
Gain on sale of real estate assets	-118,413	-95,329
Gain on sale of joint venture real estate assets	-12,667	'
Gain on acquisition of unconsolidated entity	'	-14,194
(Increase) decrease in cash in operating escrows	-12,883	6,644
Increase in resident security deposits, prepaid expenses and other assets	-66,709	-8,069
Increase (decrease) in accrued expenses, other liabilities and accrued interest payable	15,333	-16,353
Net cash provided by operating activities	469,923	375,173
Cash flows from investing activities:	'	'
Development/redevelopment of real estate assets including land acquisitions and deferred development costs	-908,215	-567,867
Acquisition of real estate assets, including partnership interest	-749,275	-105,904
Capital expenditures - existing real estate assets	-10,527	-13,449
Capital expenditures - non-real estate assets	-7,286	-1,094
Proceeds from sale of real estate, net of selling costs	432,380	182,225
Increase in payables for construction	31,124	14,419
Decrease in cash in construction escrows	'	16,944
Decrease (increase) in investments in unconsolidated real estate entities	16,788	-8,006
Net cash used in investing activities	-1,195,011	-482,732
Cash flows from financing activities:	'	'
Issuance of common stock	2,874	326,653
Dividends paid	-387,658	-270,866
Issuance of mortgage notes payable	71,210	'
Repayments of mortgage notes payable, including prepayment penalties	-1,789,399	-106,255
Issuance of unsecured notes	400,000	450,000
Settlement of interest rate contract	-51,000	-54,930
Repayment of unsecured notes	-100,000	-179,400
Payment of deferred financing costs and issuance discounts	-6,093	-6,744
Acquisition of joint venture partner equity interest	-1,965	-3,350
Redemption of preferred interest obligation	-33,327	'
Distributions to DownREIT partnership unitholders	-24	-22
Distributions to joint venture and profit-sharing partners	-238	-247
Net cash (used in) provided by financing activities	-1,895,620	154,839
Net (decrease) increase in cash and cash equivalents	-2,620,708	47,280
Cash and cash equivalents, beginning of period	2,733,618	616,853
Cash and cash equivalents, end of period	112,910	664,133
Cash paid during the period for interest, net of amount capitalized	$137,081	$101,121

CONDENSED_CONSOLIDATED_STATEME2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (USD $)	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
	Sep. 30, 2013	Sep. 30, 2012	Archstone Enterprise LP	4.61% Fixed Rate Mortgage Loan
Supplemental disclosures of non-cash investing and financing activities	'	'	'	'
Mortgage notes assumed	'	'	'	$11,958,000
Stated interest rate (as a percent)	'	'	'	4.61%
Obligation related to outstanding preferred interests	'	'	66,500,000	'
Increase in redeemable noncontrolling interests associated with business acquisition	'	'	13,262,000	'
Value of shares of common stock issued as partial consideration for acquisition	'	'	1,875,210,000	'
Assumed principal amount of indebtedness	'	'	3,512,202,000	'
Number of shares of common stock issued as partial consideration for acquisition	'	'	14,889,706	'
Common stock issued through the dividend reinvestment plan (in shares)	1,465	1,830	'	'
Common stock issued through the dividend reinvestment plan	200,000	254,000	'	'
Stock issued in connection with stock grants (in shares)	123,977	96,592	'	'
Stock issued in connection with stock grants, value	16,019,000	12,883,000	'	'
Number of shares withheld to satisfy employees' tax withholding and other liabilities	44,750	120,952	'	'
Shares withheld to satisfy employees' tax withholding and other liabilities, value	5,706,000	15,491,000	'	'
Number of shares forfeited	5,214	7,558	'	'
Shares cancelled upon forfeiture	780,000	393,000	'	'
Number of options granted for common stock	215,230	115,303	'	'
Options granted for common stock, value	5,768,000	3,357,000	'	'
Common dividends declared but not paid	138,459,000	94,778,000	'	'
Decrease in other comprehensive income due to a change in other liabilities	'	23,767,000	'	'
Deferred cash flow hedge losses reclassified to interest expense, net	4,429,000	'	'	'
Deferred cash flow hedge losses reclassified to loss on interest rate contract	53,484,000	'	'	'
Increase (decrease) in prepaid expenses and other assets due to hedge accounting	'	-11,000	'	'
Increase in redeemable noncontrolling interests	$441,000	$480,000	'	'

Organization_Basis_of_Presenta

Organization, Basis of Presentation and Significant Accounting Policies	9 Months Ended
	Sep. 30, 2013
Organization, Basis of Presentation and Significant Accounting Policies	'
Organization, Basis of Presentation and Significant Accounting Policies	'
	1. 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 consolidated subsidiaries), is a Maryland corporation that elected to be taxed as a real estate investment trust (“REIT”) under the Internal Revenue Code of 1986 (the “Code”). The Company focuses on the development, acquisition, ownership and operation of apartment communities primarily in high barrier to entry markets of the United States. The Company’s primary markets are located in the New England, Metro New York/New Jersey, Mid-Atlantic, Pacific Northwest, and Northern and Southern California regions of the country.

	At September 30, 2013, excluding real estate investments owned through the Residual JV discussed in this Form 10-Q, the Company owned or held a direct or indirect ownership interest in 247 operating apartment communities containing 73,884 apartment homes in 12 states and the District of Columbia, of which five communities containing 1,712 apartment homes were under reconstruction. In addition, the Company owned or held a direct or indirect ownership interest in 29 communities under construction that are expected to contain an aggregate of 8,692 apartment homes when completed. The Company also owned or held a direct or indirect ownership interest in land or rights to land in which the Company expects to develop an additional 45 communities that, if developed as expected, will contain an estimated 13,089 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 2012 Annual Report on Form 10-K. The results of operations for the three and nine months ended September 30, 2013 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 the meaning as 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
		9/30/13			9/30/12			9/30/13			9/30/12
	Basic and diluted shares outstanding

	Weighted average common shares - basic	129,208,839			97,044,603			126,057,793			95,742,676

	Weighted average DownREIT units outstanding	7,500			7,500			7,500			7,500

	Effect of dilutive securities (1)	—			494,466			411,821			651,382

	Weighted average common shares - diluted	129,216,339			97,546,569			126,477,114			96,401,558

	Calculation of Earnings per Share - basic

	Net (loss) income attributable to common stockholders	$	(10,715	)	$	86,844		$	100,929		$	301,512
	Net loss (income) allocated to unvested restricted shares	16			(186		)	(166		)	(1,003		)
	Net (loss) income attributable to common stockholders, adjusted	$	(10,699	)	$	86,658		$	100,763		$	300,509

	Weighted average common shares - basic	129,208,839			97,044,603			126,057,793			95,742,676

	(Loss) earnings per common share - basic	$	(0.08	)	$	0.89		$	0.8		$	3.14

	Calculation of Earnings per Share - diluted

	Net (loss) income attributable to common stockholders	$	(10,715	)	$	86,844		$	100,929		$	301,512
	Add: noncontrolling interests of DownREIT unitholders in consolidated partnerships, including discontinued operations	8			7			24			21

	Adjusted net (loss) income attributable to common stockholders	$	(10,707	)	$	86,851		$	100,953		$	301,533

	Weighted average common shares - diluted	129,216,339			97,546,569			126,477,114			96,401,558

	(Loss) earnings per common share - diluted	$	(0.08	)	$	0.89		$	0.8		$	3.13

	(1) Securities considered antidilutive for the three months ended September 30, 2013 due to recognition of net loss.

	Certain options to purchase shares of common stock in the amounts of 605,899 and 418,177 were outstanding at September 30, 2013 and 2012, respectively, but were not included in the computation of diluted earnings per share because such options were anti-dilutive.

	The Company is required to estimate the forfeiture of stock options and recognize compensation cost net of the estimated forfeitures. The estimated forfeitures included in compensation cost are adjusted to reflect actual forfeitures at the end of the vesting period. The forfeiture rate at September 30, 2013 is based on the average forfeiture activity over a period equal to the estimated life of the stock options, and was 1.2%. The application of estimated forfeitures did not materially impact compensation expense for the three and nine months ended September 30, 2013 or 2012.

	Derivative Instruments and Hedging Activities

	The Company enters into interest rate swap and interest rate cap agreements (collectively, the “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 derivative transactions for trading or other speculative purposes. The Company assesses both at inception and on an on-going basis, the effectiveness of qualifying cash flow and fair value hedges. Hedge ineffectiveness is reported as a component of general and administrative expenses. The fair values of the Hedging Derivatives that are in an asset position are recorded in prepaid expenses and other assets. The fair value of the Hedging Derivatives that are in a liability position are included in accrued expenses and other liabilities. Fair value changes for derivatives that are not in qualifying hedge relationships are reported as a component of interest expense, net. For the derivative positions that the Company has determined qualify as effective cash flow hedges, the Company has recorded the effective portion of cumulative changes in the fair value of the Hedging Derivatives in other comprehensive income. Amounts recorded in other comprehensive income 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

	The Company is involved in various claims and/or administrative proceedings that arise in the ordinary course of the Company’s business. While no assurances can be given, the Company does not believe that any of these outstanding litigation matters, individually or in the aggregate, will have a material adverse effect on the Company’s financial position 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 require the identifiable assets acquired, the liabilities assumed, and any noncontrolling interest in the acquiree to be recognized at fair value. Typical assets and liabilities acquired include land, building, furniture, fixtures, and equipment, and identified intangible assets and liabilities, consisting of the value of above-below market leases and in-place leases. In making estimates of fair values for purposes of allocating purchase price, we utilize various sources, including our own analysis of recently acquired and existing comparable properties in our portfolio and other market data.

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 period financial statements to conform to current period presentations.

Interest_Capitalized

Interest Capitalized	9 Months Ended
Interest Capitalized	Sep. 30, 2013
Interest Capitalized	'
Interest Capitalized	'
	2. Interest Capitalized

	The Company capitalizes interest during the development and redevelopment of real estate assets. Capitalized interest associated with the Company’s development or redevelopment activities totaled $17,205,000 and $12,504,000 for the three months ended September 30, 2013 and 2012, respectively, and $47,168,000 and $37,449,000 for the nine months ended September 30, 2013 and 2012, respectively.

Notes_Payable_Unsecured_Notes_

Notes Payable, Unsecured Notes and Credit Facility	9 Months Ended
Notes Payable, Unsecured Notes and Credit Facility	Sep. 30, 2013
Notes Payable, Unsecured Notes and Credit Facility	'
Notes Payable, Unsecured Notes and Credit Facility	'
	3. Notes Payable, Unsecured Notes and Credit Facility

	The Company’s mortgage notes payable, unsecured notes and Credit Facility, as defined below, as of September 30, 2013 and December 31, 2012, are summarized below (dollars in thousands). 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, 2013 and December 31, 2012, as shown in the Condensed Consolidated Balance Sheets (see Note 7, “Real Estate Disposition Activities”).

			9/30/13			12/31/12

	Fixed rate unsecured notes (1)		$	2,250,000		$	1,950,000
	Fixed rate mortgage notes payable - conventional and tax-exempt (2)		2,710,673			1,427,133
	Variable rate mortgage notes payable - conventional and tax-exempt(2)		1,011,609			476,935

	Total notes payable and unsecured notes		5,972,282			3,854,068

	Credit Facility		—			—

	Total mortgage notes payable, unsecured notes and Credit Facility		$	5,972,282		$	3,854,068

	(1) Balances at September 30, 2013 and December 31, 2012 exclude $4,809 and $4,202, respectively, of debt discount as reflected in unsecured notes on the Company’s Condensed Consolidated Balance Sheets.
	(2) Balances at September 30, 2013 and December 31, 2012 exclude $130,159 and $1,167, respectively of debt premium as reflected in mortgage notes payable on the Company’s Condensed Consolidated Balance Sheets.

	The following debt activity occurred during the nine months ended September 30, 2013:

	· In February 2013, as a portion of the consideration for the Archstone Acquisition, the Company assumed $3,512,202,000 consolidated principal amount of Archstone’s existing secured indebtedness, repaying $1,477,720,000 principal amount of the indebtedness assumed concurrent with the closing of the Archstone Acquisition.
	· In March 2013, the Company repaid $100,000,000 of its 4.95% unsecured notes in accordance with the scheduled maturity.
	· In April 2013, the Company obtained a 3.06% fixed rate, secured mortgage loan in the amount of $15,000,000 that matures in April 2018.
	· In April 2013, the Company repaid a 4.69% fixed rate, secured mortgage note in the amount of $170,125,000 pursuant to its scheduled maturity date.
	· In May 2013, the Company repaid a $5,393,000 fixed rate secured mortgage note with an interest rate of 5.55% at par and without penalty in advance of its July 2028 scheduled maturity date.
	· In May 2013, the Company obtained a 3.08% fixed rate secured mortgage loan that matures in May 2020 in the amount of $56,210,000, in association with the refinancing of an existing $47,000,000 variable rate secured mortgage note.
	· In May 2013, the Company repaid a $52,806,000 fixed rate secured mortgage note with an interest rate of 5.24% pursuant to its scheduled maturity date.
	· In September 2013, the Company issued $400,000,000 principal amount of unsecured notes in a public offering under its existing shelf registration statement for net proceeds of approximately $396,212,000. The notes mature in October 2020 and were issued at a 3.63% interest rate. The notes have an effective interest rate of 3.79% including the effect of offering costs.

	The Company has a $1,300,000,000 revolving variable rate unsecured credit facility with a syndicate of banks (the “Credit Facility”) which matures in April 2017. The Company has the option to extend the maturity by up to one year for a fee of $1,950,000. The Credit Facility bears interest at varying levels based on the London Interbank Offered Rate (“LIBOR”), rating levels achieved on our unsecured notes and on a maturity schedule selected by us. The current stated pricing is LIBOR plus 1.05% (1.23% at September 30, 2013, assuming a one month borrowing rate). The annual facility fee is approximately $1,950,000 based on the $1,300,000,000 facility size and based on our current credit rating.

	The Company had no borrowings outstanding under the Credit Facility and had $72,610,000 and $44,883,000 outstanding in letters of credit that reduced the borrowing capacity as of September 30, 2013 and December 31, 2012, respectively.

	In the aggregate, secured notes payable mature at various dates from May 2015 through July 2066, and are secured by certain apartment communities and improved land parcels (with a net carrying value of $4,697,609,000, excluding communities classified as held for sale, as of September 30, 2013).

	As of September 30, 2013, the Company has guaranteed approximately $309,358,000 of mortgage notes payable by wholly owned subsidiaries; all such mortgage notes payable are consolidated for financial reporting purposes. The weighted average interest rate of the Company’s fixed rate mortgage notes payable (conventional and tax-exempt) was 4.6% and 5.8% at September 30, 2013 and December 31, 2012, respectively. The weighted average interest rate of the Company’s variable rate mortgage notes payable and its Credit Facility, including the effect of certain financing related fees, was 2.4% and 2.7% at September 30, 2013 and December 31, 2012, respectively.

	Scheduled payments and maturities of mortgage notes payable and unsecured notes outstanding at September 30, 2013 are as follows (dollars in thousands):

												Stated
			Secured			Secured			Unsecured			interest rate
			notes			notes			notes			of unsecured
	Year		payments			maturities			maturities			notes

	2013		$	4,395		$	—		$	—		—

	2014		18,056			—			150,000			5.375	%

	2015		16,722			904,011			—			—

	2016		17,951			16,255			250,000			5.75	%

	2017		19,033			710,491			250,000			5.7	%

	2018		18,398			77,189			—			—

	2019		7,125			610,814			—			—

	2020		6,190			50,824			250,000			6.1	%

									400,000			3.625	%

2021		5,965			27,844			250,000			3.95	%

2022		6,332			—			450,000			2.95	%

2022		90,048			1,114,639			250,000			2.85	%

		$	210,215		$	3,512,067		$	2,250,000

The Company was in compliance at September 30, 2013 with certain customary financial and other covenants under the Credit Facility and the Company’s unsecured notes.

Equity

Equity	9 Months Ended
	Sep. 30, 2013
Equity	'
Equity	'
	4. Equity

	The following summarizes the changes in stockholders’ equity for the nine months ended September 30, 2013 (dollars in thousands):

						Accumulated			Accumulated			Total
				Additional		earnings			other			AvalonBay
		Common		paid-in		less			comprehensive			stockholders’			Noncontrolling		Total
		stock		capital		dividends			loss			equity			interests		equity

	Balance at December 31, 2012	$	1,144	$	7,086,407	$	(142,329	)	$	(108,007	)	$	6,837,215		$	3,578	$	6,840,793

	Net income attributable to common stockholders	—		—		100,929			—			100,929			—		100,929
	Cash flow hedge loss reclassified to earnings	—		—		—			57,913			57,913			—		57,913
	Change in redemption value of redeemable noncontrolling interest	—		—		(441		)	—			(441		)	—		(441		)
	Noncontrolling interests income allocation	—		—		—			—			—			1		1
	Dividends declared to common stockholders	—		—		(415,353		)	—			(415,353		)	—		(415,353		)
	Issuance of common stock, net of withholdings	150		1,872,684		(1,035		)	—			1,871,799			—		1,871,799
	Amortization of deferred compensation	—		17,689		—			—			17,689			—		17,689

	Balance at September 30, 2013	$	1,294	$	8,976,780	$	(458,229	)	$	(50,094	)	$	8,469,751		$	3,579	$	8,473,330

	During the nine months ended September 30, 2013, the Company:

	(i) issued 33,900 shares of common stock in connection with stock options exercised;
	(ii) issued 1,465 common shares through the Company’s dividend reinvestment plan;
	(iii) issued 123,977 common shares in connection with stock grants;
	(iv) withheld 44,750 common shares to satisfy employees’ tax withholding and other liabilities;
	(v) cancelled 5,214 shares of restricted common stock upon forfeiture; and
	(vi) issued 14,889,706 common shares in connection with the closing of the Archstone Acquisition.

	With respect to the 14,889,706 common shares issued in conjunction with the Archstone Acquisition to Lehman (as defined below), the Company and Lehman entered into a shareholders agreement (the “Shareholders Agreement”). Under the Shareholders Agreement, until February 27, 2014 Lehman will vote all of its shares of the Company’s common stock in accordance with the recommendation of the Company’s board of directors on any matter other than an extraordinary transaction. After February 14, 2014, and for so long as Lehman holds more than 5% of the Company’s common stock, Lehman will vote all of its shares of the Company’s common stock (i) in accordance with the recommendations of the Company’s board of directors with respect to any election of directors, compensation and equity plan matters, and any amendment to our charter to increase our authorized capital stock; (ii) on all matters proposed by other shareholders, either proportionately in accordance with the votes of the other shareholders or, at its election, in accordance with the recommendation of the Company’s board of directors; and (iii) on all other matters, in its sole and absolute discretion. In May 2013, Lehman sold 7,870,000 of the Company’s common shares it received as consideration for the Archstone Acquisition. Lehman received all of the net proceeds from the offering, and the sale did not impact the total number of the Company’s common shares outstanding.

	In addition, during the nine months ended September 30, 2013 the Company granted 215,230 options for common stock to employees. Any deferred compensation related to the Company’s stock option and restricted stock grants during the nine months ended September 30, 2013 is not reflected on the Company’s Condensed Consolidated Balance Sheet as of September 30, 2013, and will not be reflected until earned as compensation cost.

	In August 2012, the Company commenced a third continuous equity program (“CEP III”), under which the Company is authorized to sell up to $750,000,000 of shares of its common stock from time to time during a 36-month period. The Company had no sales under CEP III during the nine months ended September 30, 2013, and has $646,274,000 of shares that remain authorized for issuance under this program as of September 30, 2013.

Archstone_Acquisition

Archstone Acquisition	9 Months Ended
	Sep. 30, 2013
Archstone Acquisition	'
Archstone Acquisition	'
	5. Archstone Acquisition

	On February 27, 2013, pursuant to an asset purchase agreement (the “Purchase Agreement”) dated November 26, 2012, by and among the Company, Equity Residential and its operating partnership, ERP Operating Limited Partnership (together, “Equity Residential”), Lehman Brothers Holdings, Inc. (“Lehman”, which term is sometimes used in this report to refer to Lehman Brothers Holdings, Inc., and/or its relevant subsidiary or subsidiaries), and Archstone Enterprise LP (“Archstone,” which has since changed its name to Jupiter Enterprise LP), the Company, together with Equity Residential, acquired, directly or indirectly, all of Archstone’s assets, including all of the ownership interests in joint ventures and other entities owned by Archstone, and assumed Archstone’s liabilities, both known and unknown, with certain limited exceptions.

	Under the terms of the Purchase Agreement, the Company acquired approximately 40% of Archstone’s assets and liabilities and Equity Residential acquired approximately 60% of Archstone’s assets and liabilities (the “Archstone Acquisition”). The Company accounted for the acquisition as a business combination and recorded the purchase price to acquired tangible assets consisting primarily of direct and indirect interests in land and related improvements, buildings and improvements, construction in progress and identified intangible assets and liabilities, consisting primarily of the value of above and below market leases, and the value of in-places leases, at their fair values. The following table summarizes the Company’s preliminary purchase price allocation:

			Acquisition Date
			Preliminary Fair Value
			(dollars in thousands)
	Land and land improvements		$	1,760,100
	Buildings and improvements		3,729,422
	FF&E		52,290
	Construction-in-progress, including land and land held for development (1)		404,765
	In-place lease intangibles		182,467
	Other assets		85,829
	Total consolidated assets		$	6,214,873
	Interest in unconsolidated real estate entities		256,454
	Total assets		$	6,471,327
	Fair value of assumed mortgage notes payable		3,732,980
	Liability for preferred obligations		66,500
	Other liabilities		34,100
	Noncontrolling interest		13,262
	Net Assets Acquired		2,624,485
	Common shares issued		1,875,210
	Cash consideration		$	749,275

	(1) Includes amounts for in-place leases for development communities.

	The allocation of the fair values to the assets acquired and liabilities assumed is subject to further adjustment due primarily to information not readily available at the acquisition date, additional market information and final purchase price settlement with Equity Residential in accordance with the terms of the Purchase Agreement. The Company’s assessment of the fair values and the allocation of the purchase price to the identified tangible and intangible assets and assumed liabilities is its current best estimate of fair value.

	The Company engaged a third party valuation specialist to assist in the determination of the fair value of each of the component parts of the operating communities, consisting of land and land improvements, buildings and improvements, furniture, fixtures and equipment, above and below market leases and in-place lease-related intangibles.

	Land valuation was based on a market approach, whereby recent sales of similar properties were used, adjusted for differences due to location, the state of entitlement as well as the shape and size of the parcel. Improvements to the land were valued using a replacement cost approach and considered the structures and amenities included for the communities. The approach applied industry standard replacement costs adjusted for geographic specific considerations, and reduced by estimated depreciation. The value for furniture, fixtures and equipment was also determined based on a replacement cost approach, adjusted for estimated depreciation. The FF&E value estimate considered both costs for items in the apartment homes, such as appliances and furnishings, and those for common areas such as exercise facilities and on site offices. The estimate of depreciation was made considering industry standard information and depreciation curves for the identified asset classes. The fair value of buildings acquired was estimated using the replacement cost approach, assuming the buildings were vacant at acquisition. The replacement cost approach considered the composition of structures in the acquired portfolio, adjusted for an estimate of depreciation. If the operating community is held in an unconsolidated joint venture, the Company valued its interest in the operating community based on its ownership interest.

	The value of the acquired lease-related intangibles considered the estimated cost of leasing the apartment homes as if the acquired buildings were vacant, as well as the value of the current leases relative to market-rate leases. The in-place lease value was determined using an average total lease-up time, the number of apartment homes and net revenues generated during the lease-up time. The lease-up period for an apartment community was assumed to be 12 months to achieve stabilized occupancy. Net revenues were developed using market rent considering actual leasing and industry rental rate data. The value of current leases relative to a market-rate lease was based on market rents obtained for market comparables, and considered a market derived discount rate.

	The Company is applying a weighted average depreciation period for the in-place lease intangibles of six months. During the three and nine months ended September 30, 2013, the Company recognized $60,162,000 and $184,763,000, respectively, of depreciation expense for in-place lease intangibles, recorded as a component of Depreciation expense on the accompanying Condensed Consolidated Statements of Comprehensive Income.

	The Company used an internal model to determine the fair value for the development land parcels acquired. The internal model applied a discounted cash flow analysis on the expected cash flows for each land parcel as if the expected multifamily rental community is constructed. The cash flow analysis incorporated assumptions that market participants would make, including the application of (i) discount factors to the estimated future cash flows of the underlying asset, (ii) a compound annual growth rate for the revenue from the operating community, and (iii) an exit capitalization rate.

	The Company valued the Development Communities under construction and/or in lease-up using either the invested capital basis, or an internal model, depending on the stage of construction completion. For Development Communities earlier in the construction process and not yet in lease-up, invested capital was the relevant metric and was considered reflective of the fair value of the community. For Development Communities that either had completed construction or that were substantially complete with construction and in lease-up, the Company used a capitalization rate model. The capitalization rate model considered the pro-forma NOI for the Development Community, relative to NOI for comparable operating communities, with adjustments for the location and/or quality of the community. A capitalization rate was applied to each Development Community’s NOI which was based on a relevant capitalization rate observed in comparable acquisition or disposition transactions, if available, as adjusted by the Company for differences in fundamentals between the Development Community and the referenced comparable transactions.

	Given the significance of unobservable inputs, the Company has classified the valuations of the real estate assets acquired as Level 3 prices under the fair value hierarchy.

	Other assets acquired consisted primarily of working capital determined by the Company to be reflective of the fair value.

	During the nine months ended September 30, 2013, the Company recognized $82,544,000 in acquisition related expenses associated with the Archstone Acquisition, with $37,295,000 reported as a component of Equity in income (loss) of unconsolidated entities, and the balance in Expensed acquisition, development, and other pursuit costs on the accompanying Condensed Consolidated Statements of Comprehensive Income.

	Consideration

	Pursuant to the Purchase Agreement and separate arrangements between the Company and Equity Residential governing the allocation of liabilities assumed under the Purchase Agreement, the Company’s portion of consideration under the Purchase Agreement, consisted of the following:

	· the issuance of 14,889,706 shares of the Company’s common stock, valued at $1,875,210,000 as of the market’s close on February 27, 2013;
	· a cash payment of approximately $749,000,000;
	· the assumption of consolidated indebtedness with a fair value of approximately $3,732,979,000, consisting of $3,512,202,000 principal amount of consolidated indebtedness and $220,777,000 representing the amount by which fair value of the aforementioned debt exceeds the principal face value, $70,479,000 of which excess related to debt the Company repaid concurrent with the Archstone Acquisition;
	· the acquisition with Equity Residential of interests in entities that have preferred units outstanding some of which may be presented for redemption from time to time. The Company’s 40% share of the fair value of the collective obligation, including accrued dividends on these outstanding Archstone preferred units as of the closing date of the Archstone Acquisition, is approximately $66,500,000; and
	· the assumption with Equity Residential of all other liabilities, known or unknown, of Archstone, other than certain excluded liabilities. The Company shares approximately 40% of the responsibility for these liabilities.

	The Company valued the assumed mortgage notes payable using a discounted cash flow analysis that incorporated assumptions that market participants would use. 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 considered credit valuation adjustments to appropriately reflect the Company’s nonperformance risk. The Company has concluded that the value of the assumed mortgage notes payable are Level 2 prices as the majority of the inputs used to value its positions fall within Level 2 of the fair value hierarchy.

	The Company valued its obligation under the preferred units outstanding based on the current liquidation price of the respective preferred unit series, including accrued but unpaid dividends as appropriate. During the nine months ended September 30, 2013, the Company paid approximately $33,300,000 to redeem its proportionate share of a portion of the preferred interest obligations assumed in conjunction with the Archstone Acquisition. The Company used the pricing for the settlement as the fair value at February 27, 2013.

	Pro Forma Information

The following table presents information for assets acquired in the Archstone Acquisition that is included in our Condensed Consolidated Statement of Comprehensive Income from the acquisition date, February 27, 2013, through September 30, 2013 (in thousands).

		For the period including
		February 28, 2013 through
		September 30, 2013
Revenues		$	246,969
Loss attributable to common shareholders (1)		$	(128,542	)

(1) Amounts exclude acquisition costs for the Archstone Acquisition.

The following table presents the Company’s supplemental consolidated pro forma information as if the acquisition had occurred on January 1, 2012 (in thousands, except per share amounts):

		For the nine months			For the nine months
		ended September 30,			ended September 30,
		2013			2012
Revenues		$	1,152,418		$	1,053,169
Income from continuing operations		$	242,647		$	82,584
Earnings per common share - diluted (from continuing operations)		$	1.87		$	0.64

The unaudited proforma consolidated results are prepared for informational purposes only, and are based on assumptions and estimates considered appropriate by the Company’s management. However, they are not necessarily indicative of what the Company’s consolidated financial condition or results of operations actually would have been assuming the Archstone Acquisition had occurred on January 1, 2012, nor do they purport to represent the consolidated financial position or results of operations for future periods.

Investments in Archstone Consolidated Entities

In connection with the Archstone Acquisition, the Company entered into a limited liability company agreement with Equity Residential to acquire and own directly and indirectly certain Archstone entities (the “Archstone Legacy Entities”) which hold indirect interests in real estate assets, including 16 of the 60 of the consolidated communities acquired by the Company. As of September 30, 2013, the Archstone Legacy Entities have outstanding preferred interests held by unrelated third parties with an aggregate liquidation preference of approximately $91,000,000 (including accrued but unpaid distributions), which are generally subject to redemption at the election of the holders of such interests. One of the Archstone Legacy Entities previously entered into tax protection arrangements with the holders of certain of the preferred interests, which arrangements may limit for varying periods of time the Company’s and Equity Residential’s ability to dispose of the properties held indirectly by the Archstone Legacy Entities or to refinance certain related indebtedness, without making payments to the holders of such preferred interests. Pursuant to this LLC agreement, the Company has agreed to bear 40% of the economic cost of these preferred redemption obligations, and the tax protection payments that may arise from our disposition or refinancing of properties of the Archstone Legacy Entities that were contributed to a subsidiary that will be consolidated by the Company. The fair value of the Company’s proportionate share of preferred redemption obligations of approximately $36,000,000 is recorded as a component of Accrued expenses and other liabilities on the accompanying Condensed Consolidated Balance Sheets. As part of the Archstone Acquisition, the Company and Equity Residential have agreed with Lehman and Archstone to require the acquired Archstone Legacy Entities to have sufficient funds available to honor their redemption obligations and to make any payments under its tax protection arrangements, when they may become due. The principal assets indirectly held by the limited liability company that acquired the Archstone Legacy Entities are interests in a subsidiary of the Company’s (the “AvalonBay Legacy Subsidiary”) and a subsidiary of Equity Residential, each of which subsidiaries acquired certain properties formerly owned by the Archstone Legacy Entities. The Company consolidates the assets, liabilities and results of operations of the AvalonBay Legacy Subsidiary.

Investments in Archstone Unconsolidated Entities

In conjunction with the Archstone Acquisition, the Company acquired interests in the following entities:

· Archstone Multifamily Partners AC LP (the “Archstone U.S. Fund”) — The Archstone U.S. Fund was formed in July 2011 and is fully invested. As of September 30, 2013, the Archstone U.S. Fund owns nine communities containing 1,728 apartment homes, one of which includes a marina containing 229 boat slips. Through subsidiaries the Company owns the general partner of the fund and holds a 28.6% interest in the fund.

Subsidiaries of the Archstone U.S. Fund have eight loans secured by individual assets with amounts outstanding in the aggregate of $330,315,000 with varying maturity dates, ranging from 2019 to 2022. The mortgage loans are payable by the subsidiaries of the Archstone U.S. Fund with operating cash flow or disposition proceeds from the underlying real estate. The Company has not guaranteed the debt of the Archstone U.S. Fund, nor does it have any obligation to fund this debt should the Archstone U.S. Fund be unable to do so.

· Archstone Multifamily Partners AC JV LP (“the AC JV”) — The AC JV is a joint venture in which the Company assumed Archstone’s 20% ownership interest. The AC JV was formed in 2011 and as of September 30, 2013 owned two apartment communities containing 818 apartment homes in Cambridge, MA and Herndon, VA. The AC JV partnership agreement contains provisions that require the Company to provide a right of first offer (“ROFO”) to the AC JV in connection with additional opportunities to acquire or develop additional interests in multifamily real estate assets within a specified geographic radius of the two existing assets, generally one mile or less. During the three months ended September 30, 2013, the Company provided the AC JV with the opportunity to acquire a parcel of land owned by the Company as required in the right of first offer provisions for the joint venture. The AC JV exercised its right to acquire the land parcel for development, where upon it commenced construction of an additional apartment community located in Cambridge, MA, which is expected to contain 103 apartment homes and be completed for a total capitalized cost of $28,000,000. The Company sold the parcel of land to the AC JV, in exchange for a cash payment and a capital account credit, and is overseeing the development in exchange for a developer fee. The Company owns one additional land parcel for the development of 301 apartment homes, classified as a Development Right in Cambridge, MA, acquired as part of the Archstone Acquisition that is subject to ROFO restrictions. The ROFO restriction expires in 2019.

As of September 30, 2013, subsidiaries of the AC JV have eight unsecured loans outstanding in the aggregate of $162,300,000 which mature in July 2021, and which were made by the investors in the venture, including us, in proportion to the investors’ respective equity ownership interest. The unsecured loans are payable by the subsidiaries of the AC JV with operating cash flow from the venture. The Company has not guaranteed the debt of the AC JV, nor does it have any obligation to fund this debt should the AC JV be unable to do so.

· Brandywine Apartments of Maryland, LLC (“Brandywine”) — Brandywine owns a 305 apartment home community located in Washington, DC. The community is managed by a third party. Brandywine is comprised of five members who hold various interests in the joint venture. In conjunction with the Archstone Acquisition, the Company assumed a 26.1% equity interest in the venture, and subsequently purchased an additional 2.6% interest such that as of September 30, 2013, the Company now holds a 28.7% equity interest in the venture.

Brandywine has an outstanding $24,960,000 fixed rate mortgage loan that is payable by the venture. The Company has not guaranteed the debt of Brandywine, nor does the Company have any obligation to fund this debt should Brandywine be unable to do so.

· Additionally, through subsidiaries the Company and Equity Residential entered into three limited liability company agreements (collectively, the “Residual JV”) through which the Company and Equity Residential acquired (i) certain assets of Archstone that the Company and Equity Residential plan to divest (to third parties or to the Company or Equity Residential) over time (the “Residual Assets”), and (ii) various liabilities of Archstone that the Company and Equity Residential agreed to assume in conjunction with the Archstone Acquisition (the “Residual Liabilities”). The Residual Assets include interests in apartment communities in Germany (including through a fund which Archstone managed), a 20.0% interest in a joint venture which owns and manages six apartment communities with 1,902 apartment homes in the United States, two land parcels, and various licenses, insurance policies, contracts, office leases and other miscellaneous assets. The Residual Liabilities generally include most existing or future litigation and claims related to Archstone’s operations for periods before the close of the Archstone Acquisition, except for (i) claims that principally relate to the physical condition of the assets acquired directly by the Company or Equity Residential, which generally remain the sole responsibility of the Company or Equity Residential, as applicable, and (ii) certain tax and other litigation between Archstone and various equity holders in Archstone related to periods before the close of the Archstone Acquisition, and claims which may arise due to changes in the capital structure of Archstone that occurred prior to closing, for which Lehman has agreed to indemnify the Company and Equity Residential. The Company and Equity Residential jointly control the Residual JV and the Company generally holds a 40% economic interest in the assets and liabilities of the Residual JV.

Investments_in_Real_Estate_Ent

Investments in Real Estate Entities	9 Months Ended
Investments in Real Estate Entities	Sep. 30, 2013
Investments in Real Estate Entities	'
Investments in Real Estate Entities	'
	6. Investments in Real Estate Entities

	Investment in unconsolidated entities

	As of September 30, 2013, including the interests in joint ventures acquired in the Archstone Acquisition, and excluding interest in the Residual JV, the Company had investments in seven unconsolidated real estate entities with ownership interest percentages ranging from 15.2% to 31.3%. 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 months ended September 30, 2013, AvalonBay Value Added Fund, LP (“Fund I”), a real estate discretionary investment fund in which the Company has an interest of approximately 15.2%, sold Avalon at Cedar Place, located in Columbia, MD. Avalon at Cedar Place, containing 156 homes, was sold for $26,000,000. The Company’s share of the gain in accordance with GAAP for the disposition was $688,000.

	During the three months ended September 30, 2013, the Company disposed of its interest in a for-sale joint venture, which held non-depreciable real estate assets, recognizing a gain in accordance with GAAP of $975,000, reported as a component of Equity in income (loss) of unconsolidated entities on the accompanying Condensed Consolidated Statements of Comprehensive Income. Previously, the Company recognized an impairment charge of $1,955,000 associated with this venture.

	The following is a combined summary of the financial position of the entities accounted for using the equity method, excluding those owned by the Residual JV, as of the dates presented (dollars in thousands):

		9/30/13			12/31/12
		(unaudited)			(unaudited)
	Assets:
	Real estate, net	$	2,053,602		$	1,337,084
	Other assets	100,304			73,252

	Total assets	$	2,153,906		$	1,410,336

	Liabilities and partners’ capital:
	Mortgage notes payable and credit facility	$	1,358,891		$	943,259
	Other liabilities	47,717			20,405
	Partners’ capital	747,298			446,672

	Total liabilities and partners’ capital	$	2,153,906		$	1,410,336

	The following is a combined summary of the operating results of the entities accounted for using the equity method, excluding those owned by the Residual JV, for the periods presented (dollars in thousands):

		For the three months ended						For the nine months ended
		(unaudited)						(unaudited)
		9/30/13			9/30/12			9/30/13			9/30/12

	Rental and other income	$	56,240		$	43,168		$	157,456		$	130,300
	Operating and other expenses	(22,866		)	(18,733		)	(63,575		)	(56,533		)
	Gain on sale of communities	5,395			44,723			70,662			57,457
	Interest expense, net	(15,376		)	(12,742		)	(46,474		)	(38,468		)
	Depreciation expense	(15,668		)	(11,947		)	(46,602		)	(37,244		)
	Net income	$	7,725		$	44,469		$	71,467		$	55,512

	In conjunction with the formation of Fund I and AvalonBay Value Added Fund II, L.P. (“Fund II”), the Company incurred costs in excess of its equity in the underlying net assets of the respective investments. These costs represent $6,237,000 at September 30, 2013 and $7,342,000 at December 31, 2012 of the respective investment balances.

	As part of the formation of Fund I and Fund II, the Company provided separate and distinct guarantees to one of the limited partners in each of the ventures. These guarantees are specific to the respective fund and any impacts or obligation of the Company to perform under one of the guarantees has no impact on the Company’s obligations with respect to the other guarantee. The guarantees provide that, if, upon final liquidation of Fund I or Fund II, the total amount of all distributions to the guaranteed partner during the life of the respective fund (whether from operating cash flow or property sales) does not equal the total capital contributions made by that partner, then the Company will pay the guaranteed partner an amount equal to the shortfall, but in no event more than 10% of the total capital contributions made by the guaranteed partner (maximum of approximately $7,500,000 for Fund I and approximately $8,910,000 for Fund II as of September 30, 2013). As of September 30, 2013, the expected realizable values of the real estate assets owned by Fund I and Fund II are considered adequate to cover such potential payments under a liquidation scenario. The estimated fair value of, and the Company’s obligation under, these guarantees, both at inception and as of September 30, 2013, was not significant and therefore the Company has not recorded any obligation for either of these guarantees as of September 30, 2013.

	Expensed Acquisition, Development and Other Pursuit Costs and Impairment of Long-Lived Assets

	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 capitalized pre-development costs are written off with a charge to expense. The Company expensed costs related to the abandonment of Development Rights as well as costs incurred in pursuing the acquisition of assets or costs incurred pursuing the disposition of assets for which such disposition activity did not occur, in the amounts of $351,000 and $608,000 for the three months ended September 30, 2013 and 2012, respectively, and $792,000 and $1,749,000 for the nine months ended September 30, 2013 and 2012, respectively. These costs are included in Expensed acquisition, development, and other pursuit costs 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.

	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 long-lived asset may not be recoverable, the Company assesses its recoverability by comparing the carrying amount of the 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 long-lived asset. Based on periodic tests of recoverability of long-lived assets, the Company did not record any impairment losses for the three and nine months ended September 30, 2013 and 2012.

	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. The Company did not recognize any impairment charges on its investment in land for the three and nine months ended September 30, 2013 and 2012.

	The Company also evaluates its unconsolidated investments for impairment, considering both the carrying value of the investment, estimated as the expected proceeds that it would receive if the entity were dissolved and the net assets were liquidated at their current GAAP basis, as well as the Company’s proportionate share of any impairment of assets held by unconsolidated investments. There were no impairment losses recognized by any of the Company’s investments in unconsolidated entities during the three and nine months ended September 30, 2013 and 2012.

Real_Estate_Disposition_Activi

Real Estate Disposition Activities	9 Months Ended
	Sep. 30, 2013
Real Estate Disposition Activities	'
Real Estate Disposition Activities	'
	7. Real Estate Disposition Activities

	During the three months ended September 30, 2013, the Company did not sell any consolidated communities.

	As of September 30, 2013, the Company had three communities that qualified as held for sale.

	The operations for any real estate assets sold from January 1, 2012 through September 30, 2013 have been presented as income from discontinued operations in the accompanying Condensed Consolidated Statements of Comprehensive Income. Accordingly, certain reclassifications have been made to prior years to reflect discontinued operations consistent with current year presentation.

	The following is a summary of income from discontinued operations for the periods presented (dollars in thousands):

		For the three months ended						For the nine months ended
		(unaudited)						(unaudited)
		9/30/13			9/30/12			9/30/13			9/30/12

	Rental income	$	7,176		$	10,583		$	25,321		$	38,156
	Operating and other expenses	(2,229		)	(2,995		)	(7,521		)	(11,718		)
	Interest expense, net	—			—			—			(133		)
	Loss on extinguishment of debt	—			—			—			(602		)
	Depreciation expense	(1,726		)	(3,248		)	(10,727		)	(10,641		)
	Income from discontinued operations	$	3,221		$	4,340		$	7,073		$	15,062

Segment_Reporting

Segment Reporting	9 Months Ended
Segment Reporting	Sep. 30, 2013
Segment Reporting	'
Segment Reporting	'
	8. Segment Reporting

	The Company’s reportable operating segments include Established Communities, Other Stabilized Communities, and Development/Redevelopment Communities. Annually as of January 1st, the Company determines which of its communities fall into each of these categories and unless disposition or redevelopment plans regarding a community change, maintains that classification throughout the year for the purpose of reporting segment operations.

	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 segments’ performance. The Company’s chief operating decision maker 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 revenue less direct property operating expenses. 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, 2013 and 2012 is as follows (dollars in thousands):

			For the three months ended						For the nine months ended
			9/30/13			9/30/12			9/30/13			9/30/12

	Net (loss) income		$	(10,885	)	$	86,747		$	100,681		$	301,178
	Indirect operating expenses, net of corporate income		10,780			7,396			30,673			24,049
	Investments and investment management expense		1,043			1,582			3,154			4,526
	Expensed acquisition, development and other pursuit costs		2,176			608			46,041			1,749
	Interest expense, net		43,945			33,985			127,772			100,804
	Loss on interest rate contract		53,484			—			51,000			—
	Loss on extinguishment of debt, net		—			—			—			1,179
	General and administrative expense		9,878			8,372			31,262			26,398
	Equity in (income) loss of unconsolidated entities		(3,260		)	(5,553		)	16,244			(9,801		)
	Depreciation expense		160,682			62,750			457,837			183,688
	Gain on sale of real estate assets		—			—			(118,413		)	(95,329		)
	Income from discontinued operations		(3,221		)	(4,340		)	(7,073		)	(15,062		)
	Gain on acquisition of unconsolidated real estate entity		—			(14,194		)	—			(14,194		)
	Net operating income		$	264,622		$	177,353		$	739,178		$	509,185

	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 as of the beginning of the given calendar year. Therefore, each year the composition of communities within each business segment is adjusted. Accordingly, the amounts between years are not directly comparable. Segment information for the three and nine months ended September 30, 2013 and 2012 have been adjusted for the real estate assets that were sold from January 1, 2012 through September 30, 2013, or otherwise qualify as discontinued operations as of September 30, 2013, as described in Note 7, “Real Estate Disposition Activities.”

			For the three months ended								For the nine months ended
			Total						% NOI change		Total						% NOI change		Gross
			revenue			NOI			from prior year		revenue			NOI			from prior year		real estate (1)

	For the period ended September 30, 2013

	Established
	New England		$	46,319		$	29,323		(0.6	)%	$	136,528		$	88,220		2	%	$	1,398,194
	Metro NY/NJ		63,103			43,327			3.4	%	186,897			129,215			4.6	%	1,919,151
	Mid-Atlantic		25,262			17,652			(1.0	)%	75,608			54,169			1.1	%	632,102
	Pacific Northwest		11,773			7,752			1.7	%	34,752			23,539			7.4	%	443,812
	Northern California		38,491			29,905			15	%	112,569			85,627			13.1	%	1,313,694
	Southern California		30,001			20,165			4.7	%	88,873			60,640			5.7	%	1,057,512
	Total Established		214,949			148,124			4.2	%	635,227			441,410			5.5	%	6,764,465

	Other Stabilized		142,795			95,044			N/A		357,342			243,626			N/A		6,683,016
	Development / Redevelopment		32,369			21,454			N/A		79,704			54,142			N/A		2,676,384
	Land Held for Future Development		N/A			N/A			N/A		N/A			N/A			N/A		282,285
	Non-allocated (2)		3,014			N/A			N/A		8,198			N/A			N/A		47,921

	Total		$	393,127		$	264,622		49.2	%	$	1,080,471		$	739,178		45.2	%	$	16,454,071

	For the period ended September 30, 2012

	Established
	New England		$	42,755		$	27,374		2.7	%	$	125,568		$	81,268		5.6	%	$	1,287,578
	Metro NY/NJ		55,257			38,155			5.5	%	162,608			112,757			7.4	%	1,779,699
	Mid-Atlantic		26,300			18,618			3.7	%	77,825			56,156			4.2	%	591,802
	Pacific Northwest		8,401			5,984			19.6	%	24,426			17,207			13.6	%	304,381
	Northern California		31,208			22,931			15.1	%	90,853			66,646			14.5	%	1,096,166
	Southern California		25,131			17,224			6.2	%	74,000			51,225			8.8	%	946,802
Total Established		189,052			130,286			6.9	%	555,280			385,259			8.1	%	6,006,428

Other Stabilized		34,469			22,384			N/A		96,282			61,924			N/A		1,249,203
Development / Redevelopment		35,267			24,683			N/A		90,692			62,002			N/A		1,871,336
Land Held for Future Development		N/A			N/A			N/A		N/A			N/A			N/A		304,295
Non-allocated (2)		2,533			N/A			N/A		7,852			N/A			N/A		54,828

Total		$	261,321		$	177,353		14.7	%	$	750,106		$	509,185		14.6	%	$	9,486,090

(1) Does not include gross real estate assets held for sale of $318,406 and $405,662 as of September 30, 2013 and 2012, respectively.

(2) Revenue represents third party management, asset management and developer fees and miscellaneous income which are not allocated to a reportable segment.

StockBased_Compensation_Plans

Stock-Based Compensation Plans	9 Months Ended
Stock-Based Compensation Plans	Sep. 30, 2013
Stock-Based Compensation Plans	'
Stock-Based Compensation Plans	'
	9. Stock-Based Compensation Plans

	Information with respect to stock options granted under the Company’s 1994 Stock Option and Incentive Plan (the “1994 Plan”) and its 2009 Stock Option and Incentive Plan (the “2009 Plan”) are as follows (dollars in thousands, other than per share amounts):

				Weighted				Weighted
				average				average
		2009 Plan		exercise price		1994 Plan		exercise price
		shares		per share		shares		per share

	Options Outstanding, December 31, 2012	307,554		$	112.67	719,830		$	105.4
	Exercised	(9,939	)	94.73		(23,961	)	79.84
	Granted	215,230		129.03		—		—
	Forfeited	(1,267	)	131.56		(4,012	)	127.56
	Options Outstanding, September 30, 2013	511,578		$	119.85	691,857		$	106.16
	Options Exercisable September 30, 2013	194,177		$	105.48	691,857		$	106.16

	The weighted average fair value of the options granted under the 2009 Plan during the nine months ended September 30, 2013 is estimated at $26.78 per share on the date of grant using the Black-Scholes option pricing model with the following weighted average assumptions: dividend yield of 3.7% over the expected life of the option, volatility of 34.0%, risk-free interest rate of 0.9% and an expected life of approximately 5 years.

	During 2013, the Company adopted a revised compensation framework under which share-based compensation will be granted, composed of annual awards and multiyear long term incentive performance awards. Annual awards will include restricted stock awards for which one third of the award will vest annually over a three year period following the measurement period. Under the multiyear long term incentive component of the revised framework, the Company will grant a target number of restricted stock units, with the ultimate award determined by the total shareholder return of the Company’s common stock over a three-year measurement period. The share-based compensation earned will be in the form of restricted stock, or upon election of the recipient up to 25% in the form of stock options, for which one third of the award will vest annually over a three year period following the measurement period.

	During the nine months ended September 30, 2013, the Company issued 123,977 shares of restricted stock with a fair value of $16,019,000. In addition, the Company granted awards for restricted stock units, with an estimated aggregate compensation cost of $21,011,000. The grant of restricted stock units includes an award which matures at the end of 2015 as well as two transitional awards that mature at the end of 2013 and 2014. The restricted stock units were valued using a Monte Carlo model with the following weighted average assumptions: baseline share value of $130.23, a dividend yield of 2.8%, estimated volatility figures over the life of the plan using 50% historical volatility and 50% implied volatility and risk free rates over the life of the plan ranging from 0.08% to 0.37%, resulting in an average estimated fair value per restricted stock unit of $110.00.

	At September 30, 2013, the Company had 190,144 outstanding unvested shares granted under restricted stock awards. Restricted stock vesting during the nine months ended September 30, 2013 totaled 134,209 shares and had fair values at the grant date ranging from $48.60 to $149.05 per share. The total grant date fair value of shares vested was $13,857,000 and $36,232,000 for the nine months ended September 30, 2013 and 2012, respectively.

	Total employee stock-based compensation cost recognized in income was $16,768,000 and $8,394,000 for the nine months ended September 30, 2013 and 2012, respectively, and total capitalized stock-based compensation cost was $5,911,000 and $3,877,000 for the nine months ended September 30, 2013 and 2012, respectively. At September 30, 2013, there was a total of $3,421,000 and $9,451,000 in unrecognized compensation cost for unvested stock options and unvested restricted stock, respectively, which does not include estimated forfeitures. The unrecognized compensation cost for unvested stock options and restricted stock is expected to be recognized over a weighted average period of 2.00 years and 2.62 years, respectively.

Related_Party_Arrangements

Related Party Arrangements	9 Months Ended
Related Party Arrangements	Sep. 30, 2013
Related Party Arrangements	'
Related Party Arrangements	'
	10. 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 $3,014,000 and $2,533,000 in the three months ended September 30, 2013 and 2012, respectively, and $8,198,000 and $7,852,000 for the nine months ended September 30, 2013 and 2012, respectively. These fees are included in management, development and other fees on the accompanying Condensed Consolidated Statements of Comprehensive Income. In addition, the Company has outstanding receivables associated with its management role of $3,670,000 and $3,484,000 as of September 30, 2013 and December 31, 2012, respectively.

	The Company is currently acting as the general contractor for redevelopment activity in the Archstone U.S. Fund, in which the Company has a 28.6% interest, and has outstanding receivables associated with the redevelopment activity of $12,629,000 as of September 30, 2013.

	Director Compensation

	The Company recorded non-employee director compensation expense relating to restricted stock grants and deferred stock awards in the amount of $250,000 and $240,000, in the three months ended September 30, 2013 and 2012, respectively, and $743,000 and $669,000 for the nine months ended September 30, 2013 and 2012, respectively, as a component of general and administrative expense. Deferred compensation relating to restricted stock grants and deferred stock awards to non-employee directors was $666,000 and $364,000 on September 30, 2013 and December 31, 2012, respectively.

Fair_Value

Fair Value	9 Months Ended
	Sep. 30, 2013
Fair Value	'
Fair Value	'
	11. Fair Value

	Financial Instruments Carried at Fair Value

	Derivative Financial Instruments

	Currently, the Company uses 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 minimizing 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, 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, 2013, 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.

	Hedge ineffectiveness did not have a material impact on earnings of the Company for any prior period, and the Company does not anticipate that it will have a material effect in the future.

	The following table summarizes the consolidated Hedging Derivatives at September 30, 2013, excluding derivatives executed to hedge debt on communities classified as held for sale (dollars in thousands):

			Non-
			designated			Cash Flow
			Hedges			Hedges
			Interest			Interest
			Rate Caps			Rate Caps

	Notional balance		$	612,089		$	134,315
	Weighted average interest rate (1)		2.6		%	2.5		%
	Weighted average capped interest rate		5.9		%	4.9		%
	Earliest maturity date		14-Mar			15-Apr
	Latest maturity date		18-Aug			15-Jun


	(1)This represents the weighted average interest rate on the debt.

	Excluding derivatives executed to hedge secured debt on communities classified as held for sale, the Company had three derivatives designated as cash flow hedges and 14 derivatives not designated as hedges at September 30, 2013. Other than the fair value change associated with the forward interest rate protection agreement discussed below, fair value changes for derivatives not in qualifying hedge relationships for the three and nine months ended at September 30, 2013 and 2012, were not material. To adjust the Hedging Derivatives in qualifying cash flow hedges to their fair value and recognize the impact of hedge accounting, the Company recorded an increase in other comprehensive loss of $23,767,000 during the nine months ended September 30, 2012. The Company reclassified $54,948,000 and $57,913,000 of deferred losses from accumulated other comprehensive income as a change to earnings, for the three and nine months ended September 30, 2013 primarily associated with the forward interest rate protection agreement discussed below. The Company anticipates reclassifying approximately $5,493,000 of hedging losses from accumulated other comprehensive income into earnings within the next 12 months to offset the variability of cash flows of the hedged item during this period. The Company did not have any derivatives designated as fair value hedges as of September 30, 2013 or December 31, 2012.

	The Company was party to a $215,000,000 forward interest rate protection agreement, which was entered into in 2011 to reduce the impact of variability in interest rates on a portion of its expected debt issuance activity in 2013. The Company settled this position at its maturity in May 2013 with a payment to the counterparty of $51,000,000, the fair value at the time of settlement. Based on changes in the Company’s capital markets outlook for the year, the Company deemed it was probable that it would not issue the anticipated debt for which this interest rate protection agreement was transacted. During the three months ended September 30, 2013, the Company recognized the deferred loss of $53,484,000 for the forward interest rate protection agreement in Loss on interest rate contract on the accompanying Condensed Consolidated Statements of Comprehensive Income.

	Redeemable Noncontrolling Interests

	The Company provided 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 related to three ventures, two of which were acquired as part of the Archstone Acquisition. 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 DownREITs which provide 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 in 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 principal protected accounts. 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.

	Other Financial Instruments

	Rents receivable, 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 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 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 table summarizes 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):

						Quoted Prices			Significant
						in Active			Other			Significant
						Markets for			Observable			Unobservable
			Total Fair Value			Identical Assets			Inputs			Inputs
	Description		9/30/13			(Level 1)			(Level 2)			(Level 3)

	Interest Rate Caps		$	118		$	—		$	118		$	—
	Puts		(16,866		)	—			—			(16,866		)
	DownREIT units		(953		)	(953		)	—			—
	Indebtedness		(6,018,766		)	(2,317,364		)	(3,701,402		)	—
Total		$	(6,036,467	)	$	(2,318,317	)	$	(3,701,284	)	$	(16,866	)

Subsequent_Events

Subsequent Events	9 Months Ended
Subsequent Events	Sep. 30, 2013
Subsequent Events	'
Subsequent Events	'
	12. 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 2013, the Company sold Archstone Vanoni Ranch, located in Ventura, CA. Archstone Vanoni Ranch contains 316 homes and was sold for $82,000,000.

	Also in October 2013, Fund I sold Avalon Sunset, located in Los Angeles, CA. Avalon Sunset contains 82 homes and was sold for $25,800,000.

	In November 2013, the Company sold Avalon on the Sound East, located in New Rochelle, NY. Avalon on the Sound East contains 588 homes and was sold for $210,000,000.

Organization_Basis_of_Presenta1

Organization, Basis of Presentation and Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2013
Organization, Basis of Presentation and Significant Accounting Policies	'
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 consolidated subsidiaries), is a Maryland corporation that elected to be taxed as a real estate investment trust (“REIT”) under the Internal Revenue Code of 1986 (the “Code”). The Company focuses on the development, acquisition, ownership and operation of apartment communities primarily in high barrier to entry markets of the United States. The Company’s primary markets are located in the New England, Metro New York/New Jersey, Mid-Atlantic, Pacific Northwest, and Northern and Southern California regions of the country.

	At September 30, 2013, excluding real estate investments owned through the Residual JV discussed in this Form 10-Q, the Company owned or held a direct or indirect ownership interest in 247 operating apartment communities containing 73,884 apartment homes in 12 states and the District of Columbia, of which five communities containing 1,712 apartment homes were under reconstruction. In addition, the Company owned or held a direct or indirect ownership interest in 29 communities under construction that are expected to contain an aggregate of 8,692 apartment homes when completed. The Company also owned or held a direct or indirect ownership interest in land or rights to land in which the Company expects to develop an additional 45 communities that, if developed as expected, will contain an estimated 13,089 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 2012 Annual Report on Form 10-K. The results of operations for the three and nine months ended September 30, 2013 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 the meaning as 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
		9/30/13			9/30/12			9/30/13			9/30/12
	Basic and diluted shares outstanding

	Weighted average common shares - basic	129,208,839			97,044,603			126,057,793			95,742,676

	Weighted average DownREIT units outstanding	7,500			7,500			7,500			7,500

	Effect of dilutive securities (1)	—			494,466			411,821			651,382

	Weighted average common shares - diluted	129,216,339			97,546,569			126,477,114			96,401,558

	Calculation of Earnings per Share - basic

	Net (loss) income attributable to common stockholders	$	(10,715	)	$	86,844		$	100,929		$	301,512
	Net loss (income) allocated to unvested restricted shares	16			(186		)	(166		)	(1,003		)
	Net (loss) income attributable to common stockholders, adjusted	$	(10,699	)	$	86,658		$	100,763		$	300,509

	Weighted average common shares - basic	129,208,839			97,044,603			126,057,793			95,742,676

	(Loss) earnings per common share - basic	$	(0.08	)	$	0.89		$	0.8		$	3.14

	Calculation of Earnings per Share - diluted

	Net (loss) income attributable to common stockholders	$	(10,715	)	$	86,844		$	100,929		$	301,512
	Add: noncontrolling interests of DownREIT unitholders in consolidated partnerships, including discontinued operations	8			7			24			21

	Adjusted net (loss) income attributable to common stockholders	$	(10,707	)	$	86,851		$	100,953		$	301,533

	Weighted average common shares - diluted	129,216,339			97,546,569			126,477,114			96,401,558

	(Loss) earnings per common share - diluted	$	(0.08	)	$	0.89		$	0.8		$	3.13

	(1) Securities considered antidilutive for the three months ended September 30, 2013 due to recognition of net loss.

	Certain options to purchase shares of common stock in the amounts of 605,899 and 418,177 were outstanding at September 30, 2013 and 2012, respectively, but were not included in the computation of diluted earnings per share because such options were anti-dilutive.

	The Company is required to estimate the forfeiture of stock options and recognize compensation cost net of the estimated forfeitures. The estimated forfeitures included in compensation cost are adjusted to reflect actual forfeitures at the end of the vesting period. The forfeiture rate at September 30, 2013 is based on the average forfeiture activity over a period equal to the estimated life of the stock options, and was 1.2%. The application of estimated forfeitures did not materially impact compensation expense for the three and nine months ended September 30, 2013 or 2012.
Derivative Instruments and Hedging Activities	'
	Derivative Instruments and Hedging Activities

	The Company enters into interest rate swap and interest rate cap agreements (collectively, the “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 derivative transactions for trading or other speculative purposes. The Company assesses both at inception and on an on-going basis, the effectiveness of qualifying cash flow and fair value hedges. Hedge ineffectiveness is reported as a component of general and administrative expenses. The fair values of the Hedging Derivatives that are in an asset position are recorded in prepaid expenses and other assets. The fair value of the Hedging Derivatives that are in a liability position are included in accrued expenses and other liabilities. Fair value changes for derivatives that are not in qualifying hedge relationships are reported as a component of interest expense, net. For the derivative positions that the Company has determined qualify as effective cash flow hedges, the Company has recorded the effective portion of cumulative changes in the fair value of the Hedging Derivatives in other comprehensive income. Amounts recorded in other comprehensive income 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 the Company’s business. While no assurances can be given, the Company does not believe that any of these outstanding litigation matters, individually or in the aggregate, will have a material adverse effect on the Company’s financial position or results of operations.
Acquisitions of Investments in Real Estate	'
	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 require the identifiable assets acquired, the liabilities assumed, and any noncontrolling interest in the acquiree to be recognized at fair value. Typical assets and liabilities acquired include land, building, furniture, fixtures, and equipment, and identified intangible assets and liabilities, consisting of the value of above-below market leases and in-place leases. In making estimates of fair values for purposes of allocating purchase price, we utilize various sources, including our own analysis of recently acquired and existing comparable properties in our portfolio and other market data.
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	'
	Reclassifications

	Certain reclassifications have been made to amounts in prior period financial statements to conform to current period presentations.

Organization_Basis_of_Presenta2

Organization, Basis of Presentation and Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2013
Organization, Basis of Presentation and Significant Accounting Policies	'
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
		9/30/13			9/30/12			9/30/13			9/30/12
	Basic and diluted shares outstanding

	Weighted average common shares - basic	129,208,839			97,044,603			126,057,793			95,742,676

	Weighted average DownREIT units outstanding	7,500			7,500			7,500			7,500

	Effect of dilutive securities (1)	—			494,466			411,821			651,382

	Weighted average common shares - diluted	129,216,339			97,546,569			126,477,114			96,401,558

	Calculation of Earnings per Share - basic

	Net (loss) income attributable to common stockholders	$	(10,715	)	$	86,844		$	100,929		$	301,512
	Net loss (income) allocated to unvested restricted shares	16			(186		)	(166		)	(1,003		)
	Net (loss) income attributable to common stockholders, adjusted	$	(10,699	)	$	86,658		$	100,763		$	300,509

	Weighted average common shares - basic	129,208,839			97,044,603			126,057,793			95,742,676

	(Loss) earnings per common share - basic	$	(0.08	)	$	0.89		$	0.8		$	3.14

	Calculation of Earnings per Share - diluted

	Net (loss) income attributable to common stockholders	$	(10,715	)	$	86,844		$	100,929		$	301,512
	Add: noncontrolling interests of DownREIT unitholders in consolidated partnerships, including discontinued operations	8			7			24			21

	Adjusted net (loss) income attributable to common stockholders	$	(10,707	)	$	86,851		$	100,953		$	301,533

	Weighted average common shares - diluted	129,216,339			97,546,569			126,477,114			96,401,558

	(Loss) earnings per common share - diluted	$	(0.08	)	$	0.89		$	0.8		$	3.13

	(1) Securities considered antidilutive for the three months ended September 30, 2013 due to recognition of net loss.

Notes_Payable_Unsecured_Notes_1

Notes Payable, Unsecured Notes and Credit Facility (Tables)	9 Months Ended
Notes Payable, Unsecured Notes and Credit Facility (Tables)	Sep. 30, 2013
Notes Payable, Unsecured Notes and Credit Facility	'
Summary of company's mortgage notes payable, unsecured notes and Credit Facility excluding mortgage notes secured by communities classified as held for sale	'
	The Company’s mortgage notes payable, unsecured notes and Credit Facility, as defined below, as of September 30, 2013 and December 31, 2012, are summarized below (dollars in thousands).
		9/30/13		12/31/12

	Fixed rate unsecured notes (1)	$	2,250,000	$	1,950,000
	Fixed rate mortgage notes payable - conventional and tax-exempt (2)	2,710,673		1,427,133
	Variable rate mortgage notes payable - conventional and tax-exempt(2)	1,011,609		476,935

	Total notes payable and unsecured notes	5,972,282		3,854,068

	Credit Facility	—		—

	Total mortgage notes payable, unsecured notes and Credit Facility	$	5,972,282	$	3,854,068

	(1) Balances at September 30, 2013 and December 31, 2012 exclude $4,809 and $4,202, respectively, of debt discount as reflected in unsecured notes on the Company’s Condensed Consolidated Balance Sheets.
	(2) Balances at September 30, 2013 and December 31, 2012 exclude $130,159 and $1,167, respectively of debt premium as reflected in mortgage notes payable on the Company’s Condensed Consolidated Balance Sheets.
Scheduled payments and maturities of mortgage notes payable and unsecured notes outstanding	'
	Scheduled payments and maturities of mortgage notes payable and unsecured notes outstanding at September 30, 2013 are as follows (dollars in thousands):

								Stated
		Secured		Secured		Unsecured		interest rate
		notes		notes		notes		of unsecured
	Year	payments		maturities		maturities		notes

	2013	$	4,395	$	—	$	—	—

	2014	18,056		—		150,000		5.375	%

	2015	16,722		904,011		—		—

	2016	17,951		16,255		250,000		5.75	%

	2017	19,033		710,491		250,000		5.7	%

	2018	18,398		77,189		—		—

	2019	7,125		610,814		—		—

	2020	6,190		50,824		250,000		6.1	%

						400,000		3.625	%

	2021	5,965		27,844		250,000		3.95	%

	2022	6,332		—		450,000		2.95	%

	2022	90,048		1,114,639		250,000		2.85	%

		$	210,215	$	3,512,067	$	2,250,000

Equity_Tables

Equity (Tables)	9 Months Ended
	Sep. 30, 2013
Equity	'
Summary of changes in stockholders' equity	'
	The following summarizes the changes in stockholders’ equity for the nine months ended September 30, 2013 (dollars in thousands):

						Accumulated			Accumulated			Total
				Additional		earnings			other			AvalonBay
		Common		paid-in		less			comprehensive			stockholders’			Noncontrolling		Total
		stock		capital		dividends			loss			equity			interests		equity

	Balance at December 31, 2012	$	1,144	$	7,086,407	$	(142,329	)	$	(108,007	)	$	6,837,215		$	3,578	$	6,840,793

	Net income attributable to common stockholders	—		—		100,929			—			100,929			—		100,929
	Cash flow hedge loss reclassified to earnings	—		—		—			57,913			57,913			—		57,913
	Change in redemption value of redeemable noncontrolling interest	—		—		(441		)	—			(441		)	—		(441		)
	Noncontrolling interests income allocation	—		—		—			—			—			1		1
	Dividends declared to common stockholders	—		—		(415,353		)	—			(415,353		)	—		(415,353		)
	Issuance of common stock, net of withholdings	150		1,872,684		(1,035		)	—			1,871,799			—		1,871,799
	Amortization of deferred compensation	—		17,689		—			—			17,689			—		17,689

	Balance at September 30, 2013	$	1,294	$	8,976,780	$	(458,229	)	$	(50,094	)	$	8,469,751		$	3,579	$	8,473,330

Archstone_Acquisition_Tables

Archstone Acquisition (Tables)	9 Months Ended
Archstone Acquisition (Tables)	Sep. 30, 2013
Archstone Acquisition	'
Summary of preliminary purchase price allocation	'
		Acquisition Date
		Preliminary Fair Value
		(dollars in thousands)
	Land and land improvements	$	1,760,100
	Buildings and improvements	3,729,422
	FF&E	52,290
	Construction-in-progress, including land and land held for development (1)	404,765
	In-place lease intangibles	182,467
	Other assets	85,829
	Total consolidated assets	$	6,214,873
	Interest in unconsolidated real estate entities	256,454
	Total assets	$	6,471,327
	Fair value of assumed mortgage notes payable	3,732,980
	Liability for preferred obligations	66,500
	Other liabilities	34,100
	Noncontrolling interest	13,262
	Net Assets Acquired	2,624,485
	Common shares issued	1,875,210
	Cash consideration	$	749,275

	(1) Includes amounts for in-place leases for development communities.
Schedule of information for assets acquired in the acquisition that is included in condensed consolidated statement of comprehensive income from the acquisition date	'
	The following table presents information for assets acquired in the Archstone Acquisition that is included in our Condensed Consolidated Statement of Comprehensive Income from the acquisition date, February 27, 2013, through September 30, 2013 (in thousands).

		For the period including
		February 28, 2013 through
		September 30, 2013
	Revenues	$	246,969
	Loss attributable to common shareholders (1)	$	(128,542	)

	(1) Amounts exclude acquisition costs for the Archstone Acquisition.
Schedule of company's supplemental consolidated pro forma information	'
	The following table presents the Company’s supplemental consolidated pro forma information as if the acquisition had occurred on January 1, 2012 (in thousands, except per share amounts):

		For the nine months			For the nine months
		ended September 30,			ended September 30,
		2013			2012
	Revenues	$	1,152,418		$	1,053,169
	Income from continuing operations	$	242,647		$	82,584
	Earnings per common share - diluted (from continuing operations)	$	1.87		$	0.64

Investments_in_Real_Estate_Ent1

Investments in Real Estate Entities (Tables)	9 Months Ended
Investments in Real Estate Entities (Tables)	Sep. 30, 2013
Investments in Real Estate Entities	'
Combined summary of the financial position of the entities accounted for using the equity method	'
	The following is a combined summary of the financial position of the entities accounted for using the equity method, excluding those owned by the Residual JV, as of the dates presented (dollars in thousands):

		9/30/13			12/31/12
		(unaudited)			(unaudited)
	Assets:
	Real estate, net	$	2,053,602		$	1,337,084
	Other assets	100,304			73,252

	Total assets	$	2,153,906		$	1,410,336

	Liabilities and partners’ capital:
	Mortgage notes payable and credit facility	$	1,358,891		$	943,259
	Other liabilities	47,717			20,405
	Partners’ capital	747,298			446,672

	Total liabilities and partners’ capital	$	2,153,906		$	1,410,336
Combined summary of the operating results of the entities accounted for using the equity method	'
	The following is a combined summary of the operating results of the entities accounted for using the equity method, excluding those owned by the Residual JV, for the periods presented (dollars in thousands):

		For the three months ended						For the nine months ended
		(unaudited)						(unaudited)
		9/30/13			9/30/12			9/30/13			9/30/12

	Rental and other income	$	56,240		$	43,168		$	157,456		$	130,300
	Operating and other expenses	(22,866		)	(18,733		)	(63,575		)	(56,533		)
	Gain on sale of communities	5,395			44,723			70,662			57,457
	Interest expense, net	(15,376		)	(12,742		)	(46,474		)	(38,468		)
	Depreciation expense	(15,668		)	(11,947		)	(46,602		)	(37,244		)
	Net income	$	7,725		$	44,469		$	71,467		$	55,512

Real_Estate_Disposition_Activi1

Real Estate Disposition Activities (Tables)	9 Months Ended
	Sep. 30, 2013
Real Estate Disposition Activities	'
Summary of income from discontinued operations	'
	The following is a summary of income from discontinued operations for the periods presented (dollars in thousands):

		For the three months ended						For the nine months ended
		(unaudited)						(unaudited)
		9/30/13			9/30/12			9/30/13			9/30/12

	Rental income	$	7,176		$	10,583		$	25,321		$	38,156
	Operating and other expenses	(2,229		)	(2,995		)	(7,521		)	(11,718		)
	Interest expense, net	—			—			—			(133		)
	Loss on extinguishment of debt	—			—			—			(602		)
	Depreciation expense	(1,726		)	(3,248		)	(10,727		)	(10,641		)
	Income from discontinued operations	$	3,221		$	4,340		$	7,073		$	15,062

Segment_Reporting_Tables

Segment Reporting (Tables)	9 Months Ended
Segment Reporting (Tables)	Sep. 30, 2013
Segment Reporting	'
Schedule of reconciliation of NOI to net income	'
	A reconciliation of NOI to net income for the three and nine months ended September 30, 2013 and 2012 is as follows (dollars in thousands):

		For the three months ended						For the nine months ended
		9/30/13			9/30/12			9/30/13			9/30/12

	Net (loss) income	$	(10,885	)	$	86,747		$	100,681		$	301,178
	Indirect operating expenses, net of corporate income	10,780			7,396			30,673			24,049
	Investments and investment management expense	1,043			1,582			3,154			4,526
	Expensed acquisition, development and other pursuit costs	2,176			608			46,041			1,749
	Interest expense, net	43,945			33,985			127,772			100,804
	Loss on interest rate contract	53,484			—			51,000			—
	Loss on extinguishment of debt, net	—			—			—			1,179
	General and administrative expense	9,878			8,372			31,262			26,398
	Equity in (income) loss of unconsolidated entities	(3,260		)	(5,553		)	16,244			(9,801		)
	Depreciation expense	160,682			62,750			457,837			183,688
	Gain on sale of real estate assets	—			—			(118,413		)	(95,329		)
	Income from discontinued operations	(3,221		)	(4,340		)	(7,073		)	(15,062		)
	Gain on acquisition of unconsolidated real estate entity	—			(14,194		)	—			(14,194		)
	Net operating income	$	264,622		$	177,353		$	739,178		$	509,185
Schedule of details of segment information	'
	The following table provides details of the Company’s segment information as of the dates specified (dollars in thousands).

		For the three months ended								For the nine months ended
		Total						% NOI change		Total					% NOI change		Gross
		revenue			NOI			from prior year		revenue			NOI		from prior year		real estate (1)

	For the period ended September 30, 2013

	Established
	New England	$	46,319		$	29,323		(0.6	)%	$	136,528		$	88,220	2	%	$	1,398,194
	Metro NY/NJ	63,103			43,327			3.4	%	186,897			129,215		4.6	%	1,919,151
	Mid-Atlantic	25,262			17,652			(1.0	)%	75,608			54,169		1.1	%	632,102
	Pacific Northwest	11,773			7,752			1.7	%	34,752			23,539		7.4	%	443,812
	Northern California	38,491			29,905			15	%	112,569			85,627		13.1	%	1,313,694
	Southern California	30,001			20,165			4.7	%	88,873			60,640		5.7	%	1,057,512
	Total Established	214,949			148,124			4.2	%	635,227			441,410		5.5	%	6,764,465

	Other Stabilized	142,795			95,044			N/A		357,342			243,626		N/A		6,683,016
	Development / Redevelopment	32,369			21,454			N/A		79,704			54,142		N/A		2,676,384
	Land Held for Future Development	N/A			N/A			N/A		N/A			N/A		N/A		282,285
	Non-allocated (2)	3,014			N/A			N/A		8,198			N/A		N/A		47,921

	Total	$	393,127		$	264,622		49.2	%	$	1,080,471		$	739,178	45.2	%	$	16,454,071

	For the period ended September 30, 2012

	Established
	New England	$	42,755		$	27,374		2.7	%	$	125,568		$	81,268	5.6	%	$	1,287,578
	Metro NY/NJ	55,257			38,155			5.5	%	162,608			112,757		7.4	%	1,779,699
	Mid-Atlantic	26,300			18,618			3.7	%	77,825			56,156		4.2	%	591,802
	Pacific Northwest	8,401			5,984			19.6	%	24,426			17,207		13.6	%	304,381
	Northern California	31,208			22,931			15.1	%	90,853			66,646		14.5	%	1,096,166
	Southern California	25,131			17,224			6.2	%	74,000			51,225		8.8	%	946,802
	Total Established	189,052			130,286			6.9	%	555,280			385,259		8.1	%	6,006,428

	Other Stabilized	34,469			22,384			N/A		96,282			61,924		N/A		1,249,203
	Development / Redevelopment	35,267			24,683			N/A		90,692			62,002		N/A		1,871,336
	Land Held for Future Development	N/A			N/A			N/A		N/A			N/A		N/A		304,295
	Non-allocated (2)	2,533			N/A			N/A		7,852			N/A		N/A		54,828

	Total	$	261,321		$	177,353		14.7	%	$	750,106		$	509,185	14.6	%	$	9,486,090

	(1) Does not include gross real estate assets held for sale of $318,406 and $405,662 as of September 30, 2013 and 2012, respectively.

	(2) Revenue represents third party management, asset management and developer fees and miscellaneous income which are not allocated to a reportable segment.

StockBased_Compensation_Plans_

Stock-Based Compensation Plans (Tables)	9 Months Ended
Stock-Based Compensation Plans (Tables)	Sep. 30, 2013
Stock-Based Compensation Plans	'
Schedule of information with respect to stock options granted	'
	Information with respect to stock options granted under the Company’s 1994 Stock Option and Incentive Plan (the “1994 Plan”) and its 2009 Stock Option and Incentive Plan (the “2009 Plan”) are as follows (dollars in thousands, other than per share amounts):

				Weighted				Weighted
				average				average
		2009 Plan		exercise price		1994 Plan		exercise price
		shares		per share		shares		per share

	Options Outstanding, December 31, 2012	307,554		$	112.67	719,830		$	105.4
	Exercised	(9,939	)	94.73		(23,961	)	79.84
	Granted	215,230		129.03		—		—
	Forfeited	(1,267	)	131.56		(4,012	)	127.56
	Options Outstanding, September 30, 2013	511,578		$	119.85	691,857		$	106.16
	Options Exercisable September 30, 2013	194,177		$	105.48	691,857		$	106.16

Fair_Value_Tables

Fair Value (Tables)	9 Months Ended
Fair Value (Tables)	Sep. 30, 2013
Fair Value	'
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 Hedging Derivatives at September 30, 2013, excluding derivatives executed to hedge debt on communities classified as held for sale (dollars in thousands):

		Non-
		designated			Cash Flow
		Hedges			Hedges
		Interest			Interest
		Rate Caps			Rate Caps

	Notional balance	$	612,089		$	134,315
	Weighted average interest rate (1)	2.6		%	2.5		%
	Weighted average capped interest rate	5.9		%	4.9		%
	Earliest maturity date	14-Mar			15-Apr
	Latest maturity date	18-Aug			15-Jun


	(1)This represents the weighted average interest rate on the debt.
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 table summarizes 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):

					Quoted Prices			Significant
					in Active			Other			Significant
					Markets for			Observable			Unobservable
		Total Fair Value			Identical Assets			Inputs			Inputs
	Description	9/30/13			(Level 1)			(Level 2)			(Level 3)

	Interest Rate Caps	$	118		$	—		$	118		$	—
	Puts	(16,866		)	—			—			(16,866		)
	DownREIT units	(953		)	(953		)	—			—
	Indebtedness	(6,018,766		)	(2,317,364		)	(3,701,402		)	—
	Total	$	(6,036,467	)	$	(2,318,317	)	$	(3,701,284	)	$	(16,866	)

Organization_Basis_of_Presenta3

Organization, Basis of Presentation and Significant Accounting Policies (Details)	Sep. 30, 2013
	state
	home
	community
Organization and Basis of Presentation	'
Number of operating apartment communities owned	247
Number of apartment homes included in operating apartment communities owned	73,884
Number of states where operating apartment communities owned are located	12
Number of communities with apartments under reconstruction	5
Number of apartment homes under reconstruction	1,712
Number of owned communities under construction	29
Expected number of apartment homes under construction	8,692
Communities under development rights	45
Estimated number of apartment homes in communities to be developed	13,089

Organization_Basis_of_Presenta4

Organization, Basis of Presentation and Significant Accounting Policies (Details 2) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Basic and diluted shares outstanding	'	'	'	'
Weighted average common shares - basic	129,208,839	97,044,603	126,057,793	95,742,676
Weighted average DownREIT units outstanding (in shares)	7,500	7,500	7,500	7,500
Effect of dilutive securities (in shares)	'	494,466	411,821	651,382
Weighted average common shares - diluted	129,216,339	97,546,569	126,477,114	96,401,558
Calculation of Earnings per Share - basic	'	'	'	'
Net (loss) income attributable to common stockholders	($10,715)	$86,844	$100,929	$301,512
Net loss (income) allocated to unvested restricted shares	16	-186	-166	-1,003
Net (loss) income attributable to common stockholders, adjusted	-10,699	86,658	100,763	300,509
Weighted average common shares - basic	129,208,839	97,044,603	126,057,793	95,742,676
(Loss) earnings per common share - basic (in dollars per share)	($0.08)	$0.89	$0.80	$3.14
Calculation of Earnings per Share - diluted	'	'	'	'
Net (loss) income attributable to common stockholders	-10,715	86,844	100,929	301,512
Add: noncontrolling interests of DownREIT unitholders in consolidated partnerships, including discontinued operations	8	7	24	21
Adjusted net (loss) income attributable to common stockholders	($10,707)	$86,851	$100,953	$301,533
Weighted average common shares - diluted	129,216,339	97,546,569	126,477,114	96,401,558
(Loss) earnings per common share - diluted (in dollars per share)	($0.08)	$0.89	$0.80	$3.13
Options to purchase shares of common stock excluded from computation of earnings per share amount (in shares)	'	'	605,899	418,177
Estimated forfeiture rate of stock options (as a percent)	'	'	1.20%	'

Interest_Capitalized_Details

Interest Capitalized (Details) (USD $)	3 Months Ended		9 Months Ended
Interest Capitalized (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Interest Capitalized	'	'	'	'
Capitalized interest during the development and redevelopment of real estate assets	$17,205,000	$12,504,000	$47,168,000	$37,449,000

Notes_Payable_Unsecured_Notes_2

Notes Payable, Unsecured Notes and Credit Facility (Details) (USD $)

Sep. 30, 2013

Dec. 31, 2012

Feb. 27, 2013

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Mar. 31, 2013

Sep. 30, 2013

Apr. 30, 2013

31-May-13

Archstone Enterprise LP

Unsecured notes

Mortgage notes payable

4.95% unsecured notes

3.63% unsecured notes

3.06% fixed rate secured mortgage loan

4.69% secured mortgage note

5.55% secured notes

3.08% fixed-rate secured mortgage loan

5.24% fixed rate secured mortgage note

Variable rate secured mortgage note

Notes Payable, Unsecured Notes and Credit Facility

Fixed rate notes

$2,250,000,000

$1,950,000,000

$2,710,673,000

$1,427,133,000

Variable rate notes

1,011,609,000

476,935,000

Total notes payable and unsecured notes

5,972,282,000

3,854,068,000

2,250,000,000

3,512,067,000

Total mortgage notes payable, unsecured notes and Credit Facility

5,972,282,000

3,854,068,000

Amount of debt discount

4,809,000

4,202,000

Amount of debt premium

130,159,000

1,167,000

Repayment of debt

1,477,720,000

100,000,000

Principal amount of notes issued

15,000,000

56,210,000

Principal amount of notes issued

400,000,000

47,000,000

Net proceeds from issuance of debt

396,212,000

Principal amount of debt repaid

170,125,000

5,393,000

52,806,000

Stated interest rate (as a percent)

3.63%

4.95%

3.63%

3.06%

4.69%

5.55%

3.08%

5.24%

Effective interest rate, percentage

3.79%

Assumed principal amount of indebtedness

$3,512,202,000

Notes_Payable_Unsecured_Notes_3

Notes Payable, Unsecured Notes and Credit Facility (Details 2) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Mortgage notes payable	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Net carrying value of apartment communities and improved land parcels securing debt	$4,697,609,000	'
Mortgage notes payable held by wholly owned subsidiaries guaranteed by the Company	309,358,000	'
Variable rate unsecured credit facility	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Available borrowing capacity	1,300,000,000	'
Line of credit facility, extension period	'1 year	'
Extension fee	1,950,000	'
Debt instrument, basis spread on variable rate (as a percent)	1.05%	'
Debt instrument variable rate	'LIBOR	'
Current interest rate (as a percent)	1.23%	'
Period of borrowing rate assumed	'1 month	'
Annual facility fee	1,950,000	'
Borrowings outstanding under the credit facility	0	0
Outstanding balance of letters of credit	$72,610,000	$44,883,000
Fixed rate mortgage notes payable	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Weighted average interest rate, debt (as a percent)	4.60%	5.80%
Variable rate mortgage notes payable and Credit Facility	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Weighted average interest rate, debt (as a percent)	2.40%	2.70%

Notes_Payable_Unsecured_Notes_4

Notes Payable, Unsecured Notes and Credit Facility (Details 3) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Notes Payable, Unsecured Notes and Credit Facility	'	'
Mortgage notes payable and unsecured notes	$5,972,282	$3,854,068
Unsecured notes	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Mortgage notes payable and unsecured notes	2,250,000	'
Stated interest rate of unsecured notes (as a percent)	3.63%	'
Unsecured notes \| Notes payable maturing in 2014	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Mortgage notes payable and unsecured notes	150,000	'
Stated interest rate of unsecured notes (as a percent)	5.38%	'
Unsecured notes \| Notes payable maturing in 2016	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Mortgage notes payable and unsecured notes	250,000	'
Stated interest rate of unsecured notes (as a percent)	5.75%	'
Unsecured notes \| Notes payable maturing in 2017	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Mortgage notes payable and unsecured notes	250,000	'
Stated interest rate of unsecured notes (as a percent)	5.70%	'
Unsecured notes \| Notes payable maturing in 2021	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Mortgage notes payable and unsecured notes	250,000	'
Stated interest rate of unsecured notes (as a percent)	3.95%	'
Unsecured notes \| Notes Payable 6.100 Percent Maturities 2020	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Mortgage notes payable and unsecured notes	250,000	'
Stated interest rate of unsecured notes (as a percent)	6.10%	'
Unsecured notes \| Notes Payable 3.625 Percent Maturities 2020	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Mortgage notes payable and unsecured notes	400,000	'
Stated interest rate of unsecured notes (as a percent)	3.63%	'
Unsecured notes \| Notes Payable 2.950 Percent Maturities 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 \| Notes Payable 2.850 Percent Maturities 2022	'	'
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%	'
Secured notes	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	210,215	'
Mortgage notes payable and unsecured notes	3,512,067	'
Secured notes \| Notes payable maturing in 2013	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	4,395	'
Secured notes \| Notes payable maturing in 2014	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	18,056	'
Secured notes \| Notes payable maturing in 2015	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	16,722	'
Mortgage notes payable and unsecured notes	904,011	'
Secured notes \| Notes payable maturing in 2016	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	17,951	'
Mortgage notes payable and unsecured notes	16,255	'
Secured notes \| Notes payable maturing in 2017	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	19,033	'
Mortgage notes payable and unsecured notes	710,491	'
Secured notes \| Notes payable maturing in 2018	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	18,398	'
Mortgage notes payable and unsecured notes	77,189	'
Secured notes \| Notes payable maturing in 2019	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	7,125	'
Mortgage notes payable and unsecured notes	610,814	'
Secured notes \| Notes payable maturing in 2021	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	5,965	'
Mortgage notes payable and unsecured notes	27,844	'
Secured notes \| Notes Payable 6.100 Percent Maturities 2020	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	6,190	'
Mortgage notes payable and unsecured notes	50,824	'
Secured notes \| Notes Payable 2.950 Percent Maturities 2022	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	6,332	'
Secured notes \| Notes Payable 2.850 Percent Maturities 2022	'	'
Notes Payable, Unsecured Notes and Credit Facility	'	'
Secured notes payments	90,048	'
Mortgage notes payable and unsecured notes	$1,114,639	'

Equity_Details

Equity (Details) (USD $)	3 Months Ended	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013
Changes in equity	'	'
Balance	'	$6,840,793
Net income attributable to common stockholders	'	100,929
Cash flow hedge loss reclassified to earnings	54,948	57,913
Change in redemption value of redeemable noncontrolling interest	'	-441
Noncontrolling interests income allocation	'	1
Dividends declared to common stockholders	'	-415,353
Issuance of common stock, net of withholdings	'	1,871,799
Amortization of deferred compensation	'	17,689
Balance	8,473,330	8,473,330
Common stock	'	'
Changes in equity	'	'
Balance	'	1,144
Issuance of common stock, net of withholdings	'	150
Balance	1,294	1,294
Additional paid-in capital	'	'
Changes in equity	'	'
Balance	'	7,086,407
Issuance of common stock, net of withholdings	'	1,872,684
Amortization of deferred compensation	'	17,689
Balance	8,976,780	8,976,780
Accumulated earnings less dividends	'	'
Changes in equity	'	'
Balance	'	-142,329
Net income attributable to common stockholders	'	100,929
Change in redemption value of redeemable noncontrolling interest	'	-441
Dividends declared to common stockholders	'	-415,353
Issuance of common stock, net of withholdings	'	-1,035
Balance	-458,229	-458,229
Accumulated other comprehensive loss	'	'
Changes in equity	'	'
Balance	'	-108,007
Cash flow hedge loss reclassified to earnings	'	57,913
Balance	-50,094	-50,094
Total AvalonBay stockholders' equity	'	'
Changes in equity	'	'
Balance	'	6,837,215
Net income attributable to common stockholders	'	100,929
Cash flow hedge loss reclassified to earnings	'	57,913
Change in redemption value of redeemable noncontrolling interest	'	-441
Dividends declared to common stockholders	'	-415,353
Issuance of common stock, net of withholdings	'	1,871,799
Amortization of deferred compensation	'	17,689
Balance	8,469,751	8,469,751
Noncontrolling interests	'	'
Changes in equity	'	'
Balance	'	3,578
Noncontrolling interests income allocation	'	1
Balance	$3,579	$3,579

Equity_Details_2

Equity (Details 2) (USD $)	9 Months Ended			0 Months Ended	9 Months Ended	1 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Feb. 27, 2013	Sep. 30, 2013	31-May-13	Aug. 31, 2012	Sep. 30, 2013
			Minimum	Archstone	Archstone	Archstone	CEP III	CEP III
			Lehman Brothers Holdings, Inc			Lehman Brothers Holdings, Inc
Equity	'	'	'	'	'	'	'	'
Common stock shares issued in connection with stock options exercised	33,900	'	'	'	'	'	'	'
Common stock shares issued through dividend reinvestment plan	1,465	1,830	'	'	'	'	'	'
Common stock shares issued in connection with stock grants	123,977	96,592	'	'	'	'	'	'
Number of shares of stock grants withheld	44,750	120,952	'	'	'	'	'	'
Restricted common stock shares forfeited	5,214	'	'	'	'	'	'	'
Number of shares issued	'	'	'	14,889,706	14,889,706	'	'	'
Ownership percentage of common stock considered as restriction to acquire additional forms of ownership	'	'	5.00%	'	'	'	'	'
Shares sold by Lehman	'	'	'	'	'	$7,870,000	'	'
Options of common stock granted to employees (in shares)	215,230	'	'	'	'	'	'	'
Maximum value of shares of common stock that can be sold (in dollars)	'	'	'	'	'	'	750,000,000	'
Period during which common stock can be sold	'	'	'	'	'	'	'36 months	'
Value of additional shares authorized for issuance	'	'	'	'	'	'	'	$646,274,000
Common stock shares issued	'	'	'	'	'	'	'	0

Archstone_Acquisition_Details

Archstone Acquisition (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended	3 Months Ended	9 Months Ended		0 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Feb. 27, 2013	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Feb. 27, 2013	Feb. 27, 2013
					Archstone	Archstone	Archstone	Archstone	Archstone	Archstone
									Apartment communities	Equity
Archstone Acquisition	'	'	'	'	'	'	'	'	'	'
Percentage of assets and liabilities acquired	'	'	'	'	40.00%	'	'	'	'	60.00%
Land and land improvements	'	'	'	'	$1,760,100,000	'	'	'	'	'
Buildings and improvements	'	'	'	'	3,729,422,000	'	'	'	'	'
FF&E	'	'	'	'	52,290,000	'	'	'	'	'
Construction-in-progress, including land and land held for development	'	'	'	'	404,765,000	'	'	'	'	'
In-place lease intangibles	'	'	'	'	182,467,000	'	'	'	'	'
Other assets	'	'	'	'	85,829,000	'	'	'	'	'
Total consolidated assets	'	'	'	'	6,214,873,000	'	'	'	'	'
Interest in unconsolidated real estate entities	'	'	'	'	256,454,000	'	'	'	'	'
Total assets	'	'	'	'	6,471,327,000	'	'	'	'	'
Fair value of assumed mortgage notes payable	'	'	'	'	3,732,980,000	'	'	'	'	'
Liability for preferred obligations	'	'	'	'	66,500,000	'	'	'	'	'
Other liabilities	'	'	'	'	34,100,000	'	'	'	'	'
Noncontrolling interest	'	'	'	'	13,262,000	'	'	'	'	'
Net Assets Acquired	'	'	'	'	2,624,485,000	'	'	'	'	'
Common shares issued	'	'	'	'	1,875,210,000	'	'	'	'	'
Cash consideration	'	'	'	'	749,275,000	'	'	'	'	'
Acquisition related expenses	'	'	'	'	'	'	'	'	'	'
Acquisition related expenses recognized	'	'	'	'	'	'	82,544,000	'	'	'
Acquisition related expenses reported as a component of equity in income (loss) of unconsolidated entities	3,260,000	5,553,000	-16,244,000	9,801,000	'	'	37,295,000	'	'	'
Consideration	'	'	'	'	'	'	'	'	'	'
Number of shares issued	'	'	'	'	14,889,706	'	14,889,706	'	'	'
Value of shares issued	'	'	'	'	1,875,210,000	'	'	'	'	'
Cash payment	'	'	'	'	749,275,000	'	'	'	'	'
Fair value of indebtedness assumed	'	'	'	'	3,732,979,000	'	'	'	'	'
Principal amount of consolidated indebtedness	'	'	'	'	3,512,202,000	3,512,202,000	3,512,202,000	'	'	'
Debt fair value exceeds the principal face value	'	'	'	'	220,777,000	'	'	'	'	'
Redemption value of preferred equity	'	'	'	'	66,500,000	66,500,000	66,500,000	'	'	'
Preferred redemption obligations proportionate share paid	'	'	'	'	'	'	33,300,000	'	'	'
Information for acquisition that is included in condensed consolidated statement of operations comprehensive income from the acquisition date	'	'	'	'	'	'	'	'	'	'
Revenues	393,127,000	261,321,000	1,080,471,000	750,106,000	'	'	246,969,000	'	'	'
Loss attributable to common shareholders	-10,715,000	86,844,000	100,929,000	301,512,000	'	'	-128,542,000	'	'	'
Supplemental consolidated pro forma information	'	'	'	'	'	'	'	'	'	'
Revenues	'	'	'	'	'	'	1,152,418,000	1,053,169,000	'	'
Income from continuing operations	'	'	'	'	'	'	242,647,000	82,584,000	'	'
Earnings per common share - diluted (from continuing operations) (in dollars per share)	'	'	'	'	'	'	$1.87	$0.64	'	'
Lease-up period assumed to achieve stabilized occupancy	'	'	'	'	'	'	'	'	'12 months	'
Depreciation expense for in-place lease intangibles	'	'	'	'	'	60,162,000	184,763,000	'	'	'
Debt fair value exceeds the principal face value relating to debt repaid	'	'	'	'	$70,479,000	'	'	'	'	'

Archstone_Acquisition_Details_

Archstone Acquisition (Details 2) (Archstone, USD $)

0 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

Feb. 27, 2013

Sep. 30, 2013

Feb. 27, 2013

Sep. 30, 2013

Feb. 27, 2013

Sep. 30, 2013

Feb. 27, 2013

Sep. 30, 2013

community

Archstone Legacy Entities

Archstone U.S. Fund

AC JV

Brandywine

Residual JV

entity

item

home

item

Maximum

community

item

community

home

item

community

Investments in Archstone Consolidated Entities

Number of operating communities in which Archstone Legacy Entities holds indirect interest

Number of operating communities acquired

Aggregate liquidation preference

$91,000,000

Number of entities previously entered into tax protection arrangements

Percentage of the economic cost of preferred redemption obligations

40.00%

Economic cost of preferred redemption obligations fair value, proportionate share of entity

36,000,000

Investments in Archstone Unconsolidated Entities

Equity interest held (as a percent)

40.00%

28.60%

20.00%

28.70%

26.10%

20.00%

Number of apartment homes to be constructed

103

Total capitalized costs of apartment homes to be constructed

28,000,000

Number of communities owned

Number of apartment homes in communities owned

1,728

818

305

1,902

Number of apartment homes in communities for development

301

Number of marina communities

Number of boat slips

229

Number of outstanding unsecured loans

Debt outstanding

$330,315,000

$162,300,000

$24,960,000

Number of existing assets within specified geographic radius considered for right of first offer

Maximum geographic radius for existing assets within considered for right of first offer

Number of members who hold various interests in the joint venture

Additional interest purchased

2.60%

Number of limited liability company agreements

Ownership interest held by subsidiaries of the entity (as a percent)

40.00%

Number of land parcels

Investments_in_Real_Estate_Ent2

Investments in Real Estate Entities (Details) (USD $)	3 Months Ended		9 Months Ended
Investments in Real Estate Entities (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Investment in Real Estate Entities	'	'	'	'
Gain on sale of communities	$5,395,000	$44,723,000	$70,662,000	$57,457,000
Gain on acquisition of unconsolidated real estate entity	'	14,194,000	'	14,194,000
Impairment of investment in an unconsolidated entities	0	0	0	0
Fund I \| Community located in Columbia, MD	'	'	'	'
Investment in Real Estate Entities	'	'	'	'
Number of homes sold	156	'	'	'
Proceeds from sale of real estate	26,000,000	'	'	'
Gain on sale of communities	688,000	'	'	'
Unconsolidated real estate entities	'	'	'	'
Investment in Real Estate Entities	'	'	'	'
Number of unconsolidated real estate entities	7	'	7	'
Gain on acquisition of unconsolidated real estate entity	975,000	'	'	'
Impairment of investment in an unconsolidated entities	$1,955,000	'	'	'
Unconsolidated real estate entities \| Minimum	'	'	'	'
Investment in Real Estate Entities	'	'	'	'
Ownership interest percentage	15.20%	'	15.20%	'
Unconsolidated real estate entities \| Maximum	'	'	'	'
Investment in Real Estate Entities	'	'	'	'
Ownership interest percentage	31.30%	'	31.30%	'

Investments_in_Real_Estate_Ent3

Investments in Real Estate Entities (Details 2) (USD $)	3 Months Ended		9 Months Ended
Investments in Real Estate Entities (Details 2) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Assets:	'	'	'	'	'
Real estate, net	$2,053,602,000	'	$2,053,602,000	'	$1,337,084,000
Other assets	100,304,000	'	100,304,000	'	73,252,000
Total assets	2,153,906,000	'	2,153,906,000	'	1,410,336,000
Liabilities and partners' capital:	'	'	'	'	'
Mortgage notes payable and credit facility	1,358,891,000	'	1,358,891,000	'	943,259,000
Other liabilities	47,717,000	'	47,717,000	'	20,405,000
Partners' capital	747,298,000	'	747,298,000	'	446,672,000
Total liabilities and partners' capital	2,153,906,000	'	2,153,906,000	'	1,410,336,000
Combined summary of the operating results of the accounted for using the equity method	'	'	'	'	'
Rental and other income	56,240,000	43,168,000	157,456,000	130,300,000	'
Operating and other expenses	-22,866,000	-18,733,000	-63,575,000	-56,533,000	'
Gain on sale of communities	5,395,000	44,723,000	70,662,000	57,457,000	'
Interest expense, net	-15,376,000	-12,742,000	-46,474,000	-38,468,000	'
Depreciation expense	-15,668,000	-11,947,000	-46,602,000	-37,244,000	'
Net income	7,725,000	44,469,000	71,467,000	55,512,000	'
Impairment of investment in an unconsolidated entities	0	0	0	0	'
Impairment loss	0	0	0	0	'
Expensed Acquisition, Development and Other Pursuit Costs and Impairment of Long-Lived Assets	'	'	'	'	'
Expensed costs related to acquisition, development and other pursuit costs and impairment of long-lived assets	351,000	608,000	792,000	1,749,000	'
Fund I and II	'	'	'	'	'
Combined summary of the operating results of the accounted for using the equity method	'	'	'	'	'
Costs in excess of equity in underlying net assets of the respective investments	6,237,000	'	6,237,000	'	7,342,000
Maximum amount that will be paid for capital contributions made by partners (as a percent)	'	'	10.00%	'	'
AvalonBay Value Added Fund, L.P.	'	'	'	'	'
Combined summary of the operating results of the accounted for using the equity method	'	'	'	'	'
Maximum amount that will be paid for capital contributions made by partners	7,500,000	'	7,500,000	'	'
AvalonBay Value Added Fund II, L.P	'	'	'	'	'
Combined summary of the operating results of the accounted for using the equity method	'	'	'	'	'
Maximum amount that will be paid for capital contributions made by partners	$8,910,000	'	$8,910,000	'	'

Real_Estate_Disposition_Activi2

Real Estate Disposition Activities (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Summary of income from discontinued operations	'	'	'	'
Rental income	$7,176	$10,583	$25,321	$38,156
Operating and other expenses	-2,229	-2,995	-7,521	-11,718
Interest expense, net	'	'	'	-133
Loss on extinguishment of debt	'	'	'	-602
Depreciation expense	-1,726	-3,248	-10,727	-10,641
Income from discontinued operations	$3,221	$4,340	$7,073	$15,062

Segment_Reporting_Details

Segment Reporting (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting	'	'	'	'
Net (loss) income	($10,885)	$86,747	$100,681	$301,178
Indirect operating expenses, net of corporate income	10,780	7,396	30,673	24,049
Investments and investment management expense	1,043	1,582	3,154	4,526
Expensed acquisition, development and other pursuit costs	2,176	608	46,041	1,749
Interest expense, net	43,945	33,985	127,772	100,804
Loss on interest rate contract	53,484	'	51,000	'
Loss on extinguishment of debt, net	'	'	'	1,179
General and administrative expense	9,878	8,372	31,262	26,398
Equity in (income) loss of unconsolidated entities	-3,260	-5,553	16,244	-9,801
Depreciation expense	160,682	62,750	457,837	183,688
Gain on sale of real estate assets	'	'	-118,413	-95,329
Income from discontinued operations	-3,221	-4,340	-7,073	-15,062
Gain on acquisition of unconsolidated real estate entity	'	-14,194	'	-14,194
Net operating income	$264,622	$177,353	$739,178	$509,185

Segment_Reporting_Details_2

Segment Reporting (Details 2) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting	'	'	'	'
Total revenue	$393,127	$261,321	$1,080,471	$750,106
NOI	264,622	177,353	739,178	509,185
% NOI change from prior year	49.20%	14.70%	45.20%	14.60%
Gross real estate	16,454,071	9,486,090	16,454,071	9,486,090
Gross real estate assets held for sale	318,406	405,662	318,406	405,662
Established	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	214,949	189,052	635,227	555,280
NOI	148,124	130,286	441,410	385,259
% NOI change from prior year	4.20%	6.90%	5.50%	8.10%
Gross real estate	6,764,465	6,006,428	6,764,465	6,006,428
Established \| New England	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	46,319	42,755	136,528	125,568
NOI	29,323	27,374	88,220	81,268
% NOI change from prior year	-0.60%	2.70%	2.00%	5.60%
Gross real estate	1,398,194	1,287,578	1,398,194	1,287,578
Established \| Metro NY/NJ	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	63,103	55,257	186,897	162,608
NOI	43,327	38,155	129,215	112,757
% NOI change from prior year	3.40%	5.50%	4.60%	7.40%
Gross real estate	1,919,151	1,779,699	1,919,151	1,779,699
Established \| Mid-Atlantic	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	25,262	26,300	75,608	77,825
NOI	17,652	18,618	54,169	56,156
% NOI change from prior year	-1.00%	3.70%	1.10%	4.20%
Gross real estate	632,102	591,802	632,102	591,802
Established \| Pacific Northwest	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	11,773	8,401	34,752	24,426
NOI	7,752	5,984	23,539	17,207
% NOI change from prior year	1.70%	19.60%	7.40%	13.60%
Gross real estate	443,812	304,381	443,812	304,381
Established \| Northern California	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	38,491	31,208	112,569	90,853
NOI	29,905	22,931	85,627	66,646
% NOI change from prior year	15.00%	15.10%	13.10%	14.50%
Gross real estate	1,313,694	1,096,166	1,313,694	1,096,166
Established \| Southern California	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	30,001	25,131	88,873	74,000
NOI	20,165	17,224	60,640	51,225
% NOI change from prior year	4.70%	6.20%	5.70%	8.80%
Gross real estate	1,057,512	946,802	1,057,512	946,802
Other Stabilized	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	142,795	34,469	357,342	96,282
NOI	95,044	22,384	243,626	61,924
Gross real estate	6,683,016	1,249,203	6,683,016	1,249,203
Development / Redevelopment	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	32,369	35,267	79,704	90,692
NOI	21,454	24,683	54,142	62,002
Gross real estate	2,676,384	1,871,336	2,676,384	1,871,336
Land Held for Future Development	'	'	'	'
Segment Reporting	'	'	'	'
Gross real estate	282,285	304,295	282,285	304,295
Non-allocated	'	'	'	'
Segment Reporting	'	'	'	'
Total revenue	3,014	2,533	8,198	7,852
Gross real estate	$47,921	$54,828	$47,921	$54,828

StockBased_Compensation_Plans_1

Stock-Based Compensation Plans (Details) (USD $)	9 Months Ended
Stock-Based Compensation Plans (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012
Shares	'	'
Exercised (in shares)	-33,900	'
Granted (in shares)	215,230	115,303
2009 Plan \| Stock Options	'	'
Shares	'	'
Options outstanding at the beginning of the period (in shares)	307,554	'
Exercised (in shares)	-9,939	'
Granted (in shares)	215,230	'
Forfeited (in shares)	-1,267	'
Options outstanding at the end of the period (in shares)	511,578	'
Options exercisable at the end of the period (in shares)	194,177	'
Weighted average exercise price per share	'	'
Options outstanding at the beginning of the period (in dollars per share)	112.67	'
Exercised (in dollars per share)	94.73	'
Granted (in dollars per share)	129.03	'
Forfeited (in dollars per share)	131.56	'
Options outstanding at the end of the period (in dollars per share)	119.85	'
Options exercisable at the end of the period (in dollars per share)	105.48	'
1994 Plan \| Stock Options	'	'
Shares	'	'
Options outstanding at the beginning of the period (in shares)	719,830	'
Exercised (in shares)	-23,961	'
Forfeited (in shares)	-4,012	'
Options outstanding at the end of the period (in shares)	691,857	'
Options exercisable at the end of the period (in shares)	691,857	'
Weighted average exercise price per share	'	'
Options outstanding at the beginning of the period (in dollars per share)	105.4	'
Exercised (in dollars per share)	79.84	'
Forfeited (in dollars per share)	127.56	'
Options outstanding at the end of the period (in dollars per share)	106.16	'
Options exercisable at the end of the period (in dollars per share)	106.16	'

StockBased_Compensation_Plans_2

Stock-Based Compensation Plans (Details 2) (USD $)	9 Months Ended
Stock-Based Compensation Plans (Details 2) (USD $)	Sep. 30, 2013	Sep. 30, 2012
Additional disclosures	'	'
Restricted stock awards issued	123,977	'
Estimated aggregate compensation cost related to restricted stock awards	$21,011,000	'
Stock-based compensation expense	16,768,000	8,394,000
Capitalized stock-based compensation cost	5,911,000	3,877,000
Stock Options	'	'
Additional disclosures	'	'
Unrecognized compensation cost for unvested stock options	3,421,000	'
Weighted average period for recognition of unrecognized compensation cost	'2 years	'
Restricted stock	'	'
Weighted average assumptions	'	'
Percentage of granted award which will vest	33.00%	'
Award vesting period	'3 years	'
Additional disclosures	'	'
Fair value of shares issued	16,019,000	'
Outstanding unvested shares granted	190,144	'
Shares vested	134,209	'
Total fair value of shares vested	13,857,000	36,232,000
Unrecognized compensation cost for unvested restricted stock	$9,451,000	'
Weighted average period for recognition of unrecognized compensation cost	'2 years 7 months 13 days	'
Restricted stock \| Minimum	'	'
Additional disclosures	'	'
Grant date fair value per share (in dollars per share)	$48.60	'
Restricted stock \| Maximum	'	'
Additional disclosures	'	'
Grant date fair value per share (in dollars per share)	$149.05	'
Restricted stock units	'	'
Weighted average assumptions	'	'
Dividend yield (as a percent)	2.80%	'
Percentage of granted award which will vest	33.00%	'
Award vesting period	'3 years	'
Measurement period for total shareholder return of the Company's common stock	'3 years	'
Additional disclosures	'	'
Number of transitional awards maturing at the end of 2013 and 2014	2	'
Baseline share value (in dollars per share)	$130.23	'
Historical volatility (as a percent)	50.00%	'
Implied volatility (as a percent)	50.00%	'
Risk-free interest rate, minimum (as a percent)	0.08%	'
Risk-free interest rate, maximum (as a percent)	0.37%	'
Average estimated fair value (in dollars per share)	$110	'
Restricted stock units \| Maximum	'	'
Weighted average assumptions	'	'
Percentage of stock based compensation elected to be received in the form of stock options upon the election of the recipient	25.00%	'
2009 Plan \| Stock Options	'	'
Additional disclosures	'	'
Weighted average fair value per share (in dollars per share)	$26.78	'
Weighted average assumptions	'	'
Dividend yield (as a percent)	3.70%	'
Volatility (as a percent)	34.00%	'
Risk-free interest rate (as a percent)	0.90%	'
Expected life of option	'5 years	'

Related_Party_Arrangements_Det

Related Party Arrangements (Details) (USD $)	3 Months Ended		9 Months Ended
Related Party Arrangements (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Related Party Arrangements	'	'	'	'	'
Compensation expense	'	'	$16,768,000	$8,394,000	'
Archstone U.S. Fund	'	'	'	'	'
Related Party Arrangements	'	'	'	'	'
Outstanding receivables	12,629,000	'	12,629,000	'	'
Interest in affiliate (as a percent)	'	'	28.60%	'	'
Unconsolidated real estate entities	'	'	'	'	'
Related Party Arrangements	'	'	'	'	'
Asset management, property management, development and redevelopment fee revenue	3,014,000	2,533,000	8,198,000	7,852,000	'
Outstanding receivables	3,670,000	'	3,670,000	'	3,484,000
Non-employee directors \| Restricted stock and deferred stock awards	'	'	'	'	'
Related Party Arrangements	'	'	'	'	'
Compensation expense	250,000	240,000	743,000	669,000	'
Amount of deferred compensation	$666,000	'	$666,000	'	$364,000

Fair_Value_Details

Fair Value (Details) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012
	derivative	derivative	Sep. 30, 2012
Derivative instruments and Hedging Activities	'	'	'
Amount of forward interest rate protection agreement	$215,000,000	$215,000,000	'
Payment for settlement of forward starting interest rate swap agreement	'	51,000,000	'
Charge for the reversal of the deferred loss	53,484,000	'	'
Cash Flow Hedges	'	'	'
Derivative instruments and Hedging Activities	'	'	'
Number of derivative instruments held	3	3	'
Amount of increase in comprehensive loss to adjust hedging derivatives	'	'	23,767,000
Hedging losses reclassified from accumulated other comprehensive income into earnings	54,948,000	57,913,000	'
Estimated hedging losses to be reclassified from accumulated other comprehensive loss into earnings within the next twelve months	'	5,493,000	'
Cash Flow Hedges \| Interest Rate Caps	'	'	'
Derivative instruments and Hedging Activities	'	'	'
Notional balance	134,315,000	134,315,000	'
Weighted average interest rate (as a percent)	2.50%	2.50%	'
Weighted average capped interest rate (as a percent)	4.90%	4.90%	'
Non-Designated Hedges	'	'	'
Derivative instruments and Hedging Activities	'	'	'
Number of derivative instruments held	14	14	'
Non-Designated Hedges \| Interest Rate Caps	'	'	'
Derivative instruments and Hedging Activities	'	'	'
Notional balance	$612,089,000	$612,089,000	'
Weighted average interest rate (as a percent)	2.60%	2.60%	'
Weighted average capped interest rate (as a percent)	5.90%	5.90%	'

Fair_Value_Details_2

Fair Value (Details 2) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
	item
Puts	'
Financial Instruments Measured/Discussed at Fair Value	'
Number of ventures in which the entity is required to purchase interest in the investment at guaranteed minimum amount	3
Puts \| Archstone	'
Financial Instruments Measured/Discussed at Fair Value	'
Number of ventures in which the entity is required to purchase interest in the investment at guaranteed minimum amount	2
Recurring basis \| Total Fair Value	'
Financial Instruments Measured/Discussed at Fair Value	'
DownREIT units	-953
Indebtedness	-6,018,946
Total	-6,031,839
Recurring basis \| Total Fair Value \| Puts	'
Financial Instruments Measured/Discussed at Fair Value	'
Fair value of remaining outstanding Puts	-12,058
Recurring basis \| Total Fair Value \| Interest Rate Caps	'
Financial Instruments Measured/Discussed at Fair Value	'
Derivative assets	118
Recurring basis \| Quoted Prices in Active Markets for Identical Assets (Level 1)	'
Financial Instruments Measured/Discussed at Fair Value	'
DownREIT units	-953
Indebtedness	-2,317,364
Total	-2,318,317
Recurring basis \| Significant Other Observable Inputs (Level 2)	'
Financial Instruments Measured/Discussed at Fair Value	'
Indebtedness	-3,701,582
Total	-3,701,464
Recurring basis \| Significant Other Observable Inputs (Level 2) \| Interest Rate Caps	'
Financial Instruments Measured/Discussed at Fair Value	'
Derivative assets	118
Recurring basis \| Significant Unobservable Inputs (Level 3)	'
Financial Instruments Measured/Discussed at Fair Value	'
Total	-12,058
Recurring basis \| Significant Unobservable Inputs (Level 3) \| Puts	'
Financial Instruments Measured/Discussed at Fair Value	'
Fair value of remaining outstanding Puts	-12,058

Subsequent_Events_Details

Subsequent Events (Details) (Subsequent event, USD $)	1 Months Ended
	Oct. 31, 2013	Oct. 31, 2013	Nov. 30, 2013
	Archstone Vanoni Ranch	Avalon Sunset	Avalon on the Sound East
	home	Fund I	home
		home
Subsequent events	'	'	'
Number of apartment homes sold	316	82	588
Proceeds from sale of real estate	$82,000,000	$25,800,000	$210,000,000