Fair Value Measurements (Details 3) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012 Level 3	Dec. 31, 2011 Level 3	Jun. 30, 2012 Carrying Value	Sep. 30, 2012 Carrying Value Level 3	Dec. 31, 2011 Carrying Value Level 3
Fair Value, Balance Sheet Grouping [Line Items]
Debt	$ 1,391,966	$ 1,184,309		$ 1,357,730	$ 1,154,254
Notes receivable	75,729	71,297		70,000	70,000
CMBS	3,619	6,701		2,049	3,777
Other securities	$ 10,800	$ 1,230	$ 7,100	$ 8,301	$ 1,230

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investments accounted for under the cost method of accounting as of the balance sheet date.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents securitized, pay-through debt securities collateralized by real estate mortgage loans (mortgages) as of the balance sheet date which have been categorized as available-for-sale.

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