Annual report pursuant to Section 13 and 15(d)

Investment in Storage Facilities and Intangible Assets - Additional Information (Detail)

v3.10.0.1
Investment in Storage Facilities and Intangible Assets - Additional Information (Detail)
12 Months Ended
Dec. 31, 2018
USD ($)
Property
$ / shares
Dec. 31, 2017
USD ($)
Property
$ / shares
Dec. 31, 2016
USD ($)
Property
$ / shares
Dec. 31, 2015
USD ($)
Investment Holdings [Line Items]        
Number of storage facilities acquired | Property 8 2    
Cash paid for properties acquired   $ 22,600,000    
Deposits paid at the time of contract     $ 600,000 $ 500,000
Net other liabilities assumed $ 198,000 12,000 7,200,000  
Issuance of Operating Partnership Units 3,547,000   9,500,000  
Fair value of mortgage assumed $ 1,392,000   11,300,000  
Amortization period for in-place customer leases on a straight-line basis 12 months      
Amortization expense related to in-place customer leases $ 200,000 24,800,000 29,900,000  
Amortization expense to be expected for 2019 1,000,000      
Net proceeds from the sale of non-strategic properties $ 92,280,000 $ 18,872,000 34,697,000  
Sale leaseback transaction, lease terms The Company has subsequently leased one of the properties sold during 2017 and will continue to operate the property through November 2019.      
Number of properties sold, leased back | Property   1    
Sale leaseback transaction, period till property continues to operate 2019-11      
Increase in depreciation expense due to facility replacement $ 3,100,000 $ 3,700,000    
Increase in depreciation expense due to signs $ 0 $ 500,000 $ 8,200,000  
Accelerated depreciation reduced basic and diluted earnings per share | $ / shares $ 0.07 $ 0.09 $ 0.19  
Non-strategic Properties [Member]        
Investment Holdings [Line Items]        
Number of properties sold | Property 13 2 8  
Net proceeds from the sale of non-strategic properties $ 91,300,000 $ 16,900,000 $ 34,100,000  
Life Storage-HIERS Storage LLC [Member]        
Investment Holdings [Line Items]        
Company ownership interest 20.00%      
Equity investment received in joint venture $ 9,100,000      
Life Storage-HIERS Storage LLC [Member] | Non-strategic Properties [Member]        
Investment Holdings [Line Items]        
Number of properties sold | Property 12      
Gain on sale of non-strategic property $ 55,500,000