Property Transactions Property Transactions (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended		12 Months Ended
	Mar. 31, 2014 Lakeshore Park Plaza Birmingham [Member] sqft	Dec. 31, 2013 Lakeshore Park Plaza Birmingham [Member] sqft	Mar. 31, 2014 Six Hundred University Park Place Birmingham [Member] sqft	Dec. 31, 2013 Six Hundred University Park Place Birmingham [Member] sqft	Dec. 31, 2013 Tiffany Springs MarketCenter Kansas City [Member] sqft	Dec. 31, 2013 Inhibitex Suburban Atlanta [Member] sqft
Business Acquisition [Line Items]
Area of Real Estate Property	197,000	197,000	123,000	123,000	238,000	51,000
Sales Price of Property Sold Discontinued Operations			$ 19,700		$ 53,500	$ 8,300