Investment in Unconsolidated Joint Ventures (Crawford Long—CPI, LLC) (Details) (Crawford Long CPI LLC [Member], USD $)	Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]
Cash balance of joint venture	$ 3,000,000
Emory University [Member]
Schedule of Equity Method Investments [Line Items]
Ownership Percentage of partner joint venture (percent)	50.00%
Midtown Atlanta Georgia [Member]
Schedule of Equity Method Investments [Line Items]
Square footage of real estate property (square feet)	358,000
Secured Mortgage Note Payable [Member]
Schedule of Equity Method Investments [Line Items]
Outstanding amount of mortgage note payable of joint venture	$ 46,500,000
Interest rate on mortgage loan (percent)	5.90%