Organization - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2017 segment store state
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of operating storage facilities in which the entity has equity interests (in stores)	1,020
Number of stores owned by franchisees and third parties	421
Number of operating stores owned and/or managed	1,441
Number of states in which operating storage facilities are located | state	38
Number of reportable segments | segment	3
Rental Revenue [Member] | Customer Concentration Risk [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Percentage of rental income accounted for by any single tenant (no more than)	5.00%