Subsequent Events (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	9 Months Ended
Oct. 31, 2011	Sep. 30, 2011
Subsequent Events [Abstract]
Date Dividends Declared		2011-10
Date Dividends Will Be Paid		2011-11
Common Stock, Dividends Per Share, Declared (dollars per share)		$ 0.1451875
Preferred Stock Class D, Dividends Per Share, Declared (dollars per share)		$ 0.1536459
Preferred Stock Class E, Dividends Per Share, Declared (dollars per share)		$ 0.140625
Proceeds from note receivable issued in connection with a Crest property sale	$ 2.9
Friendly Ice Cream Corporation Bankruptcy of Tenant [Member]
Subsequent Event [Line Items]
Subsequent Event Date	2011-10
Subsequent Events Description	In October 2011, Friendly Ice Cream Corporation, or Friendly's, one of our tenants, filed for voluntary reorganization under Chapter 11 of the U.S. Bankruptcy Code. Friendly's leases 121 properties from us that, as of September 30, 2011, represented 3.6% of our rental revenue. Friendly's rejected 15 of the 121 locations in October 2011. We do not anticipate that this filing will have a material impact on our operations and financial position, or on our ability to pay and increase the amount of the monthly dividend.
Leased Properties	121
Rental Revenue Percentage Tenant in Bankruptcy (in hundredths)		3.60%
Leased Property Locations Rejected	15

Number of locations contractually leased by client in bankruptcy proceedings.

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Number of locations rejected by client in bankruptcy proceedings.

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Aggregate dividends declared during the period for each share of preferred stock class D outstanding.

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Rental revenue percentage of total contractually obligated by client in bankruptcy proceedings.

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The date of subsequent event occurrence or of indication that subsequent event occurred.

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Month and year subsequent event occurrence or of indication that subsequent event occurred.

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Aggregate dividends declared during the period for each share of common stock outstanding.

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The month and year (YYYY-MM) that the dividend declared as of or prior to the financial reporting date will be paid in the subsequent period.

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The cash inflow associated with principal collections from a borrowing supported by a written promise to pay an obligation.

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Describes the event or transaction that occurred between the balance sheet date and the date the financial statements are issued or available to be issued.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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