Disposals and Other Significant Transactions (Details Textual) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2016 USD ($) Property	Mar. 31, 2015 USD ($)	Dec. 31, 2015 Property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(Loss) income before income taxes and gain on disposition | $	$ 23,698	$ 18,457
Wholly And Partially Owned Consolidated Properties [Member] | Assets Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Apartment Communities	0
Disposal Group Disposed Of By Sale, Prior Year [Member] | Wholly And Partially Owned Consolidated Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Apartment communities sold			11
Apartment homes sold			3,855
(Loss) income before income taxes and gain on disposition | $		$ 4,100