Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

v3.10.0.1
Summary of Significant Accounting Policies - Additional Information (Detail)
3 Months Ended 12 Months Ended
Mar. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Property
shares
Dec. 31, 2017
USD ($)
Property
shares
Dec. 31, 2016
USD ($)
Property
shares
Schedule Of Significant Accounting Policies [Line Items]        
Noncontrolling limited partnership unit redemption value   one common share or cash    
Number of units issued for acquisition | shares   35,457    
Fair value of units, issued for acquisition   $ 3,547,000    
Number of partnership unit redeemed | shares   3,972    
Allowance for doubtful accounts   $ 500,000 $ 700,000  
Advertising costs   11,300,000 12,300,000 $ 9,500,000
Acquisition related costs   0 0 29,542,000
Depreciation expense   102,300,000 102,700,000 87,200,000
Capitalized interest   600,000 300,000 100,000
Impairment charges   0 0 0
Property deposits   1,100,000 900,000  
Write-off of acquired property deposits   0 0 $ 1,783,000
Number of acquisitions cancelled | Property       2
Federal and state income tax expense, current   1,700,000    
Deferred income taxes   1,386,000 (2,578,000)  
Unrecognized tax benefits   0 0  
Interest or penalties related to uncertain tax provisions   0 0  
Prepaid taxes   100,000 100,000  
Deferred tax assets   2,100,000 3,600,000  
Deferred tax liability   $ 1,600,000 $ 1,700,000  
Corporate income tax rate   21.00% 35.00%  
Number of leased real estate properties under extension options, operates for self-storage facilities | Property   2    
Number of leased properties under purchase options | Property   1    
Option to purchase property under lease   $ 13,300,000    
Number of properties acquired | Property   8 2  
Stock option expense   $ 7,000 $ 15,000 $ 89,000
Amortization of non-vested stock grants   $ 6,000,000 $ 7,100,000 $ 7,200,000
Options granted during period | shares   0 0 0
Chief Executive Officer, David Rogers [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Compensation expense   $ 900,000    
Scenario Forecast [Member] | Chief Executive Officer, David Rogers [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Compensation expense $ 400,000      
ASU 2016-02 [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Right-of-use asset and related lease liability   $ 16,000,000    
ASU 2017-01 [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Number of properties acquired | Property   8 0  
General and Administrative Expense [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Federal and state income tax expense (benefit)   $ 3,100,000 $ (1,000,000) $ 400,000
Minimum [Member] | ASU 2016-02 [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Percentage of remaining economic life of asset to define the lease term, major part   75.00%    
Percentage of fair value of underlying asset to define the lease term, substantially all   90.00%    
Minimum [Member] | Revenue [Member] | Product Concentration [Member] | Revenue From Rental Products [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Concentration risk, percentage   90.00%    
Maximum [Member] | ASU 2016-02 [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Percentage of total economic life of underlying asset to define the lease term, at or near the end   25.00%    
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 LP [Member]        
Schedule Of Significant Accounting Policies [Line Items]        
Units of redeemable noncontrolling interest in operating partnership | shares   248,966 217,481  
Acquisition related costs       29,542,000
Write-off of acquired property deposits       1,783,000
Deferred income taxes   $ 1,386,000 $ (2,578,000)  
Stock option expense   $ 7,000 $ 15,000 $ 89,000
Life Storage LP [Member]        
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%    
Warehouse Anywhere LLC [Member] | Life Storage Solutions, LLC [Member]        
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   60.00%