Real Estate Entities and Investments in Affiliates - Investments in Affiliates (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012
Investments in and Advances to Affiliates [Line Items]
Investments in affiliates	$ 31,338,000	$ 30,799,000	$ 30,257,000
Joint Venture Unconsolidated [Member]
Investments in and Advances to Affiliates [Line Items]
Equity Method Investment, Summarized Financial Information, Assets	166,601,000	166,112,000	156,992,000
Equity Method Investments Summarized Financial Information Net Assets	95,490,000	92,106,000	85,162,000
Investments in affiliates	31,338,000	30,799,000	30,257,000
Joint Venture Unconsolidated [Member] | Other Affiliates [Member]
Investments in and Advances to Affiliates [Line Items]
Equity Method Investments	31,338,000	30,799,000	30,257,000
Joint Venture Unconsolidated [Member] | Equity Method Investments in Non Real Estate Affiliate [Member]
Investments in and Advances to Affiliates [Line Items]
Equity Method Investments	10,850,000	11,024,000	11,384,000
Real Estate Segment [Member] | Joint Venture Unconsolidated [Member] | Equity Method investments in Real Estate Affiliates [Member] | Real Estate Entities [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Investments in and Advances to Affiliates [Line Items]
Equity Method Investments	20,488,000	19,775,000	18,873,000
Real Estate Segment [Member] | Joint Venture Unconsolidated [Member] | Residential real estate [Member] | Equity Method investments in Real Estate Affiliates [Member] | Real Estate Entities [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Investments in and Advances to Affiliates [Line Items]
Equity Method Investments	14,000,000	13,800,000	12,800,000
Real Estate Segment [Member] | Joint Venture Unconsolidated [Member] | Minimum [Member] | Real Estate Entities [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Investments in and Advances to Affiliates [Line Items]
Real Estate Development Projects Range of Total Assets	1,900,000
Real Estate Segment [Member] | Joint Venture Unconsolidated [Member] | Maximum [Member] | Real Estate Entities [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Investments in and Advances to Affiliates [Line Items]
Real Estate Development Projects Range of Total Assets	$ 49,700,000