Investments in Real Estate Entities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) community home loan extension agreement investor mi	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2016 USD ($)	Jan. 31, 2016 USD ($)	Feb. 27, 2013
Schedule of Equity Method Investments [Line Items]
Gain on sale of other real estate	$ 10,224	$ 9,647	$ 490
Gain on sale of communities	$ 196,749	98,899	333,221
Number of Communities Acquired | community	4
Gain (Loss) on Extinguishment of Debt	$ (7,075)	26,736	(412)
Number of Limited Liability Company Agreements | agreement	3
Number of Apartment Homes in Communities Owned | home	79,228
Payment for Redemption of Preferred Interest Obligation	$ 1,960	14,410	6,300
Investments in unconsolidated real estate entities	175,116	216,919
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity	38,015	40,978
Expensed acquisition, development and other pursuit costs, net of recoveries	$ 9,922	6,822	(3,717)
Avalon Hoboken [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Homes, Acquired | home	217
Purchase price	$ 129,700
Avalon Hoboken [Member] | Notes Payable Maturities 2020 [Member] | Secured notes
Schedule of Equity Method Investments [Line Items]
Assumed principal amount of indebtedness					$ 67,904
Debt Instrument, Interest Rate, Effective Percentage					4.18%
Avalon Potomac Yard [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Homes, Acquired | home	323
Purchase price	$ 108,250
Avalon Columbia Pike [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Homes, Acquired | home	269
Purchase price	$ 102,000
Avalon Columbia Pike [Member] | Notes Payable Maturities 2019 [Member] | Secured notes
Schedule of Equity Method Investments [Line Items]
Assumed principal amount of indebtedness				$ 70,507
Debt Instrument, Interest Rate, Effective Percentage				3.38%
Studio 77 [Member]
Schedule of Equity Method Investments [Line Items]
Number of Apartment Homes, Acquired | home	156
Purchase price	$ 72,100
Acquired Real Estate [Member]
Schedule of Equity Method Investments [Line Items]
Expensed acquisition, development and other pursuit costs, net of recoveries	$ 5,139	3,806	(7,681)
Archstone Enterprise LP
Schedule of Equity Method Investments [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired						40.00%
Equity Residential and its Operating Partnership and ERP Operating Limited Partnership [Member] | Archstone Enterprise LP
Schedule of Equity Method Investments [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired						60.00%
Fund II
Schedule of Equity Method Investments [Line Items]
Number of Institutional Investors | investor	6
Real Estate Investments, Joint Ventures	$ 19,737
Equity Method Investment, Ownership Percentage	31.30%
Number of apartment communities sold | community	3
Number of Apartment Homes Sold | home	1,514
Gain on sale of communities	$ 41,501	$ 29,726	21,624
Repayments of secured mortgages	156,248
Gain (Loss) on Extinguishment of Debt	$ (1,768)
Percentage of Right of Distribution	20.00%
Percentage of Right of Remaining Distribution	80.00%
Equity in income of unconsolidated entities relating to the Company's recognition of promoted interest	$ 7,985
Number of loans secured by individual assets | loan	4
Debt outstanding	$ 128,008
Fund II | Eaves Rancho San Diego [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Real Estate	158,000
Fund II | Eaves Tustin [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Real Estate	163,550
Fund II | Eaves Rockville [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Real Estate	$ 61,400
US Fund
Schedule of Equity Method Investments [Line Items]
Number of Institutional Investors | investor	6
Real Estate Investments, Joint Ventures	$ 49,693
Equity Method Investment, Ownership Percentage	28.60%
Number of apartment communities sold | community	2
Number of Apartment Homes Sold | home	461
Gain on sale of communities	$ 16,568
Repayments of secured mortgages	94,822
Gain (Loss) on Extinguishment of Debt	$ 2,003
Number of loans secured by individual assets | loan	8
Debt outstanding	$ 274,255
Number of extension options | extension	2
Period of extension (in years)	1 year
US Fund | Archstone Boca Town Center [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Real Estate	$ 56,300
US Fund | Avalon Kips Bay [Member]
Schedule of Equity Method Investments [Line Items]
Proceeds from Sale of Real Estate	$ 173,000
ACJV
Schedule of Equity Method Investments [Line Items]
Number of Institutional Investors | investor	4
Real Estate Investments, Joint Ventures	$ 50,674
Equity Method Investment, Ownership Percentage	20.00%
Maximum geographic radius for existing assets within considered for right of first offer | mi	1
Number of loans secured by individual assets | loan	8
Debt outstanding	$ 162,300
MVPI LLC
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	25.00%
Percentage of Right of Distribution		45.00%
Equity in income of unconsolidated entities relating to the Company's recognition of promoted interest		$ 21,340	$ 930
Number of Apartment Homes in Communities Owned | home	313
MVPI LLC | Joint Venture Agreement Modification [Member]
Schedule of Equity Method Investments [Line Items]
Payments for (Proceeds from) Other Real Estate Partnerships		$ 20,680
Brandywine [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	28.70%
Debt outstanding	$ 23,307
Number of Apartment Homes in Communities Owned | home	305
Number of Members who Hold Various Interests in Joint Venture | investor	5
SWIB [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	20.00%
Residual JV
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	40.00%
Legacy JV [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	40.00%
Preferred Interest Obligation Liquidation Value	$ 39,921
Sudbury [Member]
Schedule of Equity Method Investments [Line Items]
Real Estate Investments, Joint Ventures	$ 6,680
Equity Method Investment, Ownership Percentage	60.00%
Avalon Clarendon [Member]
Schedule of Equity Method Investments [Line Items]
Real Estate Investments, Joint Ventures	$ 120,300
Number of Apartment Homes, Acquired | home	300
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain	$ 4,322
Investments in unconsolidated real estate entities	115,848
AVA North Point [Member]
Schedule of Equity Method Investments [Line Items]
Real Estate Investments, Joint Ventures	$ 12,398
Equity Method Investment, Ownership Percentage	55.00%
Gain on sale of other real estate	$ 10,621
Number of Apartment Homes in Communities Owned | home	265
AVA North Point [Member] | Joint Venture Partner [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	45.00%
Sheepshead Bay [Member]
Schedule of Equity Method Investments [Line Items]
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	70.00%
Variable Interest Entity, Ownership Interest by Partner	30.00%
Due from Related Parties	$ 27,241