Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended		1 Months Ended
	Dec. 31, 2014 property sqft	Dec. 31, 2013	Jan. 29, 2015 property sqft	Jan. 23, 2015 sqft property	Feb. 11, 2015 property sqft
Subsequent Event [Line Items]
Number of buildings	126				11
Area of real estate property	9,300,000.0				641,593.0
Purchase price	$ 236.7	$ 212.4
Industrial Building In Washington, D.C. [Member]
Subsequent Event [Line Items]
Number of buildings			6
Area of real estate property			820,207.0
Purchase price			115.5
Subsequent Event [Member] | Industrial Building In Doral, Florida [Member]
Subsequent Event [Line Items]
Number of buildings				1
Area of real estate property				106,810.0
Purchase price				$ 9.9