The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References+ Details

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 16

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

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-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 35

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-URI http://asc.fasb.org/extlink&oid=16383099&loc=d3e25351-111560

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-2/124-2

-Paragraph 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Investments in Real Estate Entities (Details) (USD $)	3 Months Ended		9 Months Ended
Investments in Real Estate Entities (Details) (USD $)	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Investment in Real Estate Entities
Gain on sale of communities	$ 5,395,000	$ 44,723,000	$ 70,662,000	$ 57,457,000
Gain on acquisition of unconsolidated real estate entity		14,194,000		14,194,000
Impairment of investment in an unconsolidated entities	0	0	0	0
Fund I \| Community located in Columbia, MD
Investment in Real Estate Entities
Number of homes sold	156
Proceeds from sale of real estate	26,000,000
Gain on sale of communities	688,000
Unconsolidated real estate entities
Investment in Real Estate Entities
Number of unconsolidated real estate entities	7		7
Gain on acquisition of unconsolidated real estate entity	975,000
Impairment of investment in an unconsolidated entities	$ 1,955,000
Unconsolidated real estate entities \| Minimum
Investment in Real Estate Entities
Ownership interest percentage	15.20%		15.20%
Unconsolidated real estate entities \| Maximum
Investment in Real Estate Entities
Ownership interest percentage	31.30%		31.30%