Fair Value Fair Value (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage notes payable	$ 288,355,000	$ 272,613,000
Unsecured debt	536,000,000	476,500,000
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage notes payable	0	0
Unsecured debt	0	0
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage notes payable	0	0
Unsecured debt	541,524,000	489,558,000
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage notes payable	307,558,000	283,728,000
Unsecured debt	$ 0	$ 0
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan to value ratios	41.00%
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loan to value ratios	52.00%