Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Acquisition I [Member]
Subsequent Event [Line Items]
Subsequent event, date	Jan. 31, 2012
Subsequent event, description	In January 2012, the Company acquired Bon Terra, a 60-unit community located adjacent to Delano in Redmond, Washington for 16.0 million.
Number of units	60
Subsequent event, amount	$ 16.0
Acquisition II [Member]
Subsequent Event [Line Items]
Subsequent event, date	Jan. 31, 2012
Subsequent event, description	Also in January, the Company acquired Reed Square, a 100-unit community located in Sunnyvale, California for 23.0 million.
Number of units	100
Subsequent event, amount	23.0
Sale [Member]
Subsequent Event [Line Items]
Subsequent event, description	The Company is in contract to sell two communities located in San Diego, California for approximately 28.4 million for a gain by the end of the first quarter of 2012
Number of communities	2
Subsequent event, amount	$ 28.4