Annual report pursuant to Section 13 and 15(d)

INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURE - Narrative (Details)

v3.6.0.2
INVESTMENT IN UNCONSOLIDATED REAL ESTATE VENTURE - Narrative (Details)
$ in Thousands, ft² in Millions
12 Months Ended
Oct. 04, 2016
USD ($)
ft²
storage_unit
state
property
$ / property
Dec. 31, 2016
USD ($)
ft²
storage_unit
state
property
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Business Acquisition [Line Items]        
Goodwill   $ 5,750 $ 0  
Pro forma revenue   234,525 204,580 $ 127,943
Pro forma net income   $ 40,209 (7,906) (2,220)
Schedule of Equity Method Investments [Line Items]        
Number of self storage properties | property   382    
Total rentable square feet in self storage properties | ft²   23.1    
Number of storage units owned | storage_unit   184,000    
Number of states that self storage properties are owned in | state   20    
Investment in unconsolidated real estate venture   $ 81,486 0  
Equity in losses of unconsolidated real estate venture   (1,484) 0 $ 0
Property Management Platform [Member]        
Business Acquisition [Line Items]        
Aggregate purchase price $ 20,000      
Tangible fixed assets acquired 400      
Goodwill 5,800      
Pro forma revenue   4,900 6,300  
Pro forma net income   $ 600 $ 700  
Property Management Platform [Member] | Trade Names [Member]        
Business Acquisition [Line Items]        
Trade name acquired 3,200      
Service Agreements [Member] | Property Management Platform [Member]        
Business Acquisition [Line Items]        
Management contract acquired $ 10,600      
Amortization period of acquired management contract asset   15 years    
Joint Venture [Member]        
Schedule of Equity Method Investments [Line Items]        
Equity method investment, monthly property management fee, percent 6.00%      
Equity method investment, annual call center fee, percent 1.00%      
Equity method investment, monthly platform fee (in dollars per property) | $ / property 1,250      
Equity method investment, acquisition fee, percent 0.65%      
Equity method investment, acquisition fee, term 4 years      
Equity method investment, development management fee, percent 3.00%      
Equity method investment, warranty protection exchange, proceeds given in exchange, percent 50.00%      
Investment in unconsolidated real estate venture   $ 81,500    
Equity in losses of unconsolidated real estate venture   (1,500)    
Joint Venture [Member] | IStorage Facilities [Member]        
Schedule of Equity Method Investments [Line Items]        
Aggregate purchase price of JV portfolio $ 630,000      
Number of self storage properties | property 66      
Total rentable square feet in self storage properties | ft² 4.5      
Number of storage units owned | storage_unit 36,000      
Number of states that self storage properties are owned in | state 12      
Total equity contributed by JV Partners to Joint Venture $ 320,000      
Equity contributed by JV Partner to Joint Venture $ 80,000      
Equity method investment, ownership percentage 25.00%      
State Pension Fund [Member] | Joint Venture [Member] | IStorage Facilities [Member]        
Schedule of Equity Method Investments [Line Items]        
Equity contributed by JV Partner to Joint Venture $ 240,000      
Equity method investment, ownership percentage 75.00%      
Joint Venture [Member]        
Schedule of Equity Method Investments [Line Items]        
Management and other fees   1,800    
Outside basis capitalized in investment in unconsolidated real estate venture   $ 3,200    
Line of Credit [Member] | Revolving line of credit [Member] | Credit Facility [Member]        
Business Acquisition [Line Items]        
Effective interest rate   2.17% 2.03% 2.66%