Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.8.0.1
Summary of Significant Accounting Policies - Additional Information (Detail)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
USD ($)
shares
Dec. 31, 2016
USD ($)
Property
shares
Dec. 31, 2015
USD ($)
$ / shares
Schedule Of Significant Accounting Policies [Line Items]        
Percentage of ownership interest of the subsidiary and its limited partnership which controls the operations of the Operating Partnership   99.50%    
Units of redeemable noncontrolling interest in operating partnership | shares   217,481 217,481  
Noncontrolling limited partnership unit redemption value   one common share or cash    
Number of units issued for acquisition | shares     90,477  
Fair value of units, issued for acquisition     $ 9,516,000  
Number of partnership Units redeemed | shares     41,862  
Allowance for doubtful accounts   $ 700,000 $ 1,000,000  
Advertising costs   12,300,000 9,500,000 $ 7,300,000
Acquisition related costs   0 29,542,000 2,991,000
Depreciation expenses   102,700,000 87,200,000 55,100,000
Capitalized interest   300,000 100,000 100,000
Impairment charges   0    
Cash held in escrow for encumbered properties   292,000 238,000  
Property deposits   900,000 2,400,000  
Write-off of acquired property deposits   0 $ 1,783,000 0
Number of acquisitions cancelled | Property     2  
Federal and state income tax expense, current   1,500,000    
Deferred income taxes   (2,578,000)    
Unrecognized tax benefits   0 $ 0  
Interest or penalties related to uncertain tax provisions   0 0  
Prepaid taxes   100,000 400,000  
Deferred tax assets   3,600,000 1,500,000  
Deferred tax liability   $ 1,700,000 2,200,000  
Corporate income tax rate   35.00%    
Stock option expense   $ 15,000 89,000 210,000
Amortization of non-vested stock grants   $ 7,100,000 $ 7,200,000 $ 6,300,000
Weighted-average fair value of options granted | $ / shares       $ 9.90
Options granted during period | shares   0 0  
Scenario Forecast [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Corporate income tax rate 21.00%      
General and Administrative Expense [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Federal and state income tax expense   $ (1,000,000) $ 400,000 $ 1,300,000
Minimum [Member] | Sales Revenue, Net | Product Concentration [Member] | Revenue From Rental Products [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Concentration risk, percentage   90.00%    
Building and Improvements [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Estimated useful lives, (in years)   40 years    
Furniture, Fixtures and Equipment [Member] | Minimum [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Estimated useful lives, (in years)   5 years    
Furniture, Fixtures and Equipment [Member] | Maximum [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Estimated useful lives, (in years)   20 years    
Life Storage Solutions, LLC [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Percentage of ownership by subsidiary   60.00%