Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Inputs, Level 3 [Member]
Fair Value, Balance Sheet Grouping [Line Items]
Debt	$ 1,744,702	$ 1,674,019
Notes receivable	43,630	43,957
CMBS	3,560	2,980
Other securities	12,889	10,800
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping [Line Items]
Debt	1,704,986	1,633,452
Notes receivable	40,000	40,000
CMBS	2,096	2,075
Other securities	$ 8,301	$ 8,301

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.

+ References+ Details

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.

+ References+ Details