Quarterly report pursuant to Section 13 or 15(d)

Investment in Joint Ventures - Additional Information (Detail)

v3.4.0.3
Investment in Joint Ventures - Additional Information (Detail)
3 Months Ended 12 Months Ended
Mar. 31, 2016
USD ($)
Property
Mar. 31, 2015
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Property
Dec. 31, 2013
USD ($)
Dec. 31, 2012
USD ($)
Property
Dec. 31, 2011
USD ($)
Property
Dec. 31, 2008
USD ($)
Property
Schedule of Equity Method Investments [Line Items]                
Investment at carrying value $ 64,985,000   $ 62,520,000          
Equity in income of joint ventures $ 915,000 $ 646,000            
Sovran HHF Storage Holdings LLC [Member]                
Schedule of Equity Method Investments [Line Items]                
Percentage ownership in unconsolidated joint venture 20.00%              
Investment at carrying value $ 44,300,000   44,600,000          
Payment for property acquisition       $ 187,200,000       $ 171,500,000
Number of properties owned and managed under twenty-percent stake joint venture | Property 39             25
Additional number of properties owned and managed under twenty-percent stake joint venture | Property       14        
Contribution of company to joint venture as share in capital       $ 28,600,000   $ 1,200,000   $ 18,600,000
Receipt of return of capital distribution         $ 3,400,000      
Excess of investment over net asset due to capitalization of acquisition related costs $ 1,700,000              
Other-than-temporary impairment recorded on investment 0              
Sovran HHF Storage Holdings LLC [Member] | Acquisitions 2014 [Member]                
Schedule of Equity Method Investments [Line Items]                
Contribution of company to joint venture as share in capital     400,000          
Sovran HHF Storage Holdings II LLC [Member]                
Schedule of Equity Method Investments [Line Items]                
Investment at carrying value $ 13,900,000   13,900,000          
Payment for property acquisition           29,000,000 $ 166,100,000  
Contribution of company to joint venture as share in capital     1,700,000     $ 2,400,000 $ 12,800,000  
Percentage of variable interest ownership in unconsolidated joint venture 15.00%              
Number of properties owned and managed under fifteen-percent stake joint venture | Property 30         10 20  
Sovran HHF and Sovran HHF II [Member]                
Schedule of Equity Method Investments [Line Items]                
Management and call center fee as a percentage of revenues 7.00%              
Management and call center fee earned $ 1,200,000 1,200,000            
Equity in income of joint ventures $ 800,000 600,000            
Urban Box Coralway Storage, LLC [Member]                
Schedule of Equity Method Investments [Line Items]                
Percentage ownership in unconsolidated joint venture 85.00%              
Contribution of company to joint venture as share in capital     4,000,000          
Management and call center fee as a percentage of revenues 6.00%              
Management and call center fee earned $ 0   0          
Iskalo Office Holdings, LLC [Member]                
Schedule of Equity Method Investments [Line Items]                
Percentage ownership in unconsolidated joint venture 49.00%              
Equity in income of joint ventures $ 59,000 58,000            
Investment liability at carrying value (500,000)   (500,000)          
Rent paid during the period $ 300,000 $ 300,000            
SNL/Orix 1200 McDonald Ave., LLC [Member]                
Schedule of Equity Method Investments [Line Items]                
Percentage ownership in unconsolidated joint venture 5.00%              
Management and call center fee earned $ 0   $ 0          
SNL/Orix 1200 McDonald Ave., LLC [Member] | Common Stock Shares [Member]                
Schedule of Equity Method Investments [Line Items]                
Contribution of company to joint venture as share in capital 400,000              
SNL/Orix 1200 McDonald Ave., LLC [Member] | Preferred Stock [Member]                
Schedule of Equity Method Investments [Line Items]                
Contribution of company to joint venture as share in capital $ 2,300,000