Real Estate Disposition Activities (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012 home community	Dec. 31, 2011	Dec. 31, 2010
Summary of income from discontinued operations
Gross sales price	$ 280,550,000	$ 292,965,000	$ 198,600,000
Number of communities sold	4
Number of communities held for sale	1
South Clark (Land)
Summary of income from discontinued operations
Gross sales price	12,300,000
Net proceeds	10,849,000
Waterford, Avalon Arlintgon Heights, Avalon Wildreed and Avalon Highgrove
Summary of income from discontinued operations
Apartment homes	1,578	1,038	1,007
Net proceeds	274,018,000	287,358,000	194,009,000
Waterford
Summary of income from discontinued operations
Apartment homes	544
Gross sales price	86,500,000
Net proceeds	84,488,000
Avalon Arlington Heights
Summary of income from discontinued operations
Apartment homes	409
Gross sales price	87,250,000
Net proceeds	86,888,000
Avalon Wildreed
Summary of income from discontinued operations
Apartment homes	234
Gross sales price	35,000,000
Net proceeds	33,994,000
Avalon HighGrove
Summary of income from discontinued operations
Apartment homes	391
Gross sales price	59,500,000
Net proceeds	$ 57,799,000