Subsequent Events - Narrative (Details) $ in Millions	1 Months Ended		9 Months Ended
	Oct. 31, 2015 USD ($) ft² property building	Jan. 31, 2013 property building	Sep. 30, 2015 ft² property building	Sep. 30, 2014 ft²
Subsequent Event [Line Items]
Number of properties sold or agreed to be sold | property		3
Number of buildings sold		18
Property square feet | ft²			25,286,000	42,919,000
Disposed of by Sale
Subsequent Event [Line Items]
Number of properties sold or agreed to be sold | property			82
Number of buildings sold			117
Property square feet | ft²			16,368,645
Subsequent event | Disposed of by Sale
Subsequent Event [Line Items]
Number of properties sold or agreed to be sold | property	7
Number of buildings sold	13
Property square feet | ft²	1,263,809
Gross proceeds from sale of real estate anticipated | $	$ 131.2