Fair Value of Financial Instruments (Valuation Techniques Used to Measure the Fair Value of the Plan's Level 3 Investments) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Comm Drive, LLC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 8,557
Capitalization rate	8.50%
Discount rate	9.50%
Duration (in years)	10 years
CTE Drive, LLC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	6,922
Capitalization rate	8.50%
Discount rate	10.00%
Duration (in years)	15 years
Oakbrook Parkway LLC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	24,955
Capitalization rate	8.50%
Discount rate	10.50%
Duration (in years)	10 years
West Jefferson, LLC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	29,318
Capitalization rate	8.50%
Discount rate	10.50%
Duration (in years)	10 years
MacCorkle Ave SE, LLC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	15,987
Capitalization rate	8.85%
S Pike Road West, LLC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,079
Capitalization rate	10.50%
N US 131, LLC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,063
Capitalization rate	10.00%
E Stockton Blvd, LLC [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 5,170
Capitalization rate	9.00%