Investment in Storage Facilities and Intangible Assets - Additional Information (Detail) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) Property $ / shares	Mar. 31, 2017 USD ($)
Real Estate [Abstract]
Number of storage facilities acquired | Property	0
Amortization period for in-place customer leases on a straight-line basis	12 months
Amortization expense related to in-place customer leases	$ 0.0	$ 12.8
Increase in depreciation expense due to facility replacement	$ 0.3
Accelerated depreciation reduced basic and diluted earnings per share | $ / shares	$ 0.01