Real Estate Investments (Development Activities) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) development_project	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Land and construction in progress	$ 10,700		$ 20,000
Number of development projects completed | development_project	36
Aggregate cost to date	$ 52,300
Number of remaining projects to be completed | development_project	1
Estimated completion period for remaining projects	6 months
Number of development projects placed into service | development_project	4
Aggregate cost of projects placed in service	$ 11,300
Capitalized interest expense	200	$ 300
Total commitment	800
Land and Construction in Progress [Member]
Business Acquisition [Line Items]
Tenant Improvements	$ 7,100
2016 Acquisitions [Member]
Business Acquisition [Line Items]
Development projects in progress | development_project	2
Investment to date	$ 3,581
Estimated cost to complete	1,937
Total Investment	$ 5,518