Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012 Carrying (Reported) Amount, Fair Value Disclosure [Member]	Jun. 30, 2012 Carrying (Reported) Amount, Fair Value Disclosure [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2011 Carrying (Reported) Amount, Fair Value Disclosure [Member] Fair Value, Inputs, Level 3 [Member]		Jun. 30, 2012 Estimate of Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 3 [Member]		Dec. 31, 2011 Estimate of Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning balance	$ 1,419	$ 0	$ 1,419	$ 0
Fair Value Assets Gains Or Losses Realized And Unrealized [Abstract]
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Gain Loss Included In Earnings 1	0	66	0	66
Purchases	0	1,617	0	1,617
Ending balance	1,419	1,683	1,419	1,683
Change in Unrealized Gain (Loss) Included in Other Income	0	66	0	66
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt						1,276,174	[1]	1,154,254	[1]	1,309,329	[1]	1,184,309	[1]
CMBS						2,028	[2]	3,777	[2]	3,392	[2]	6,701	[2]
Notes Receivable						70,000	[1]	70,000	[1]	75,134	[1]	71,297	[1]
Other securities					$ 7,100	$ 8,301	[3]	$ 1,230	[3]	$ 10,800	[3]	$ 1,230	[3]

[1] We determined the estimated fair value of our debt and notes receivable instruments using a discounted cash flow model with rates that take into account the credit of the tenants and interest rate risk. We also considered the value of the underlying collateral taking into account the quality of the collateral, the credit quality of the company, the time until maturity and the current interest rate.

[2] The carrying value of our commercial mortgage-backed securities (“CMBS”) represents historical cost, as we have deemed these securities to be held-to-maturity, and is inclusive of impairment charges recognized during 2012 and 2009. There were no purchases or sales during the six months ended June 30, 2012.

[3] During June 2012, we acquired equity securities in a warehouse and logistics company for a total cost of $7.1 million, representing a follow-on transaction of our $1.2 million investment that we made during 2011.