Potential Acquisitions - Additional Information (Detail) $ in Millions			3 Months Ended		9 Months Ended
	Sep. 19, 2016 USD ($) Property	Mar. 25, 2016 USD ($) Property	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) Property	Sep. 30, 2015 USD ($)
Business Acquisition [Line Items]
Number of self storage facilities | Property					66
Business acquisition, purchase price | $			$ 1.1	$ 0.3	$ 11.8	$ 3.1
Potential Acquisition of 27 Property Portfolio
Business Acquisition [Line Items]
Business acquisition purchase price | $		$ 371.0
Number of self storage facilities | Property		22
Potential Acquisition of 27 Property Portfolio | First Phase
Business Acquisition [Line Items]
Business acquisition purchase price | $		$ 275.0
Number of self storage facilities | Property		11
Aurora Colorado
Business Acquisition [Line Items]
Number of self storage facilities | Property	1
Business acquisition, purchase price | $	$ 10.1