Commitments and Contingencies (Details Textual) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Long-term Purchase Commitment [Line Items]
Contract to purchase apartment community currently under construction	$ 320.0
Payment deposits for purchase of apartment community under construction		$ 25.0
Commitments related to development, redevelopment and capital improvement activities [Member]
Long-term Purchase Commitment [Line Items]
Commitments related to capital spending activities	$ 85.0
Time Period of Long-term Purchase Commitment	12 months
Expected Additional Investment in Construction Projects	$ 7.0
Long-term construction loan commitment	$ 20.1
Minimum [Member]
Long-term Purchase Commitment [Line Items]
Compliance Period For Low Income Housing Tax Credit Syndication Agreements	1 year
Maximum [Member]
Long-term Purchase Commitment [Line Items]
Compliance Period For Low Income Housing Tax Credit Syndication Agreements	10 years
Maximum [Member] | Commitments related to operations [Member]
Long-term Purchase Commitment [Line Items]
Time Period of Long-term Purchase Commitment	1 year