Real Estate Entities and Investments in Affiliates - Investments in Affiliates (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Investments in and Advances to Affiliates [Line Items]
Investments in affiliates	$ 31,421,000	$ 30,799,000	$ 28,521,000
Joint Venture Unconsolidated [Member]
Investments in and Advances to Affiliates [Line Items]
Equity Method Investment, Summarized Financial Information, Assets	160,422,000	166,112,000	158,431,000
Equity Method Investments Summarized Financial Information Net Assets	93,771,000	92,106,000	87,197,000
Investments in affiliates	31,421,000	30,799,000	28,521,000
Joint Venture Unconsolidated [Member] | Other Affiliates [Member]
Investments in and Advances to Affiliates [Line Items]
Equity Method Investments	31,421,000	30,799,000	28,521,000
Joint Venture Unconsolidated [Member] | Equity Method Investments in Non Real Estate Affiliate [Member]
Investments in and Advances to Affiliates [Line Items]
Equity Method Investments	11,043,000	11,024,000	10,958,000
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	20,378,000	19,775,000	17,563,000
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	14,085,000	13,813,000	12,217,000
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	$ 47,200,000