Investments In Real Estate (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	May 07, 2015 property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of investments in real estate		$ 126,500,000
Assets	9,408,426,000	9,526,784,000
Total liabilities	5,550,565,000	5,612,546,000
Consideration received on sale of property	45,300,000
Net gain on sale of discontinued operation	17,800,000
Midwest and Northeast Regions
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties		5
Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties	2	5
Assets	81,700,000	120,500,000
Total liabilities	3,200,000	5,800,000
Number of properties sold	2
Number of properties reclassified	1
Catch up depreciation	300,000
Held-for-sale | Assets Identified for Disposal Subsequent to First Quarter 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets	15,600,000
Total liabilities	$ 300,000
Held-for-sale | Subsequent Event | Assets Identified for Disposal Subsequent to First Quarter 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties			1
Fiscal Year-End 2014 Identified Properties for Disposal
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties	3