Discontinued Operations (Narrative) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014 property	Dec. 31, 2013 property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	13
Number of properties held for sale	7	8
Property held for sale	$ 73.0	$ 155.0
Property held for sale, accumulated depreciation		32.4
Gross property included in discontinued operations		68.6
Accumulated depreciation for properties included in discontinued operations		$ 13.2
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	12	20
Number of properties held for sale		8
Discontinued Operations [Member] | California [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold		1
Discontinued Operations [Member] | Florida [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	2	3
Number of properties held for sale		2
Discontinued Operations [Member] | Georgia [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	3
Number of properties held for sale		3
Discontinued Operations [Member] | Louisiana [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	2
Discontinued Operations [Member] | Nevada [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold		1
Discontinued Operations [Member] | New Mexico [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold		2
Discontinued Operations [Member] | North Carolina [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	2	3
Number of properties held for sale		1
Discontinued Operations [Member] | Tennessee [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold		1
Discontinued Operations [Member] | Texas [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	3	9
Number of properties held for sale		2
Discontinued Operations [Member] | Center Sold Not Including Held For Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	4