Quarterly report pursuant to Section 13 or 15(d)

ORGANIZATION AND NATURE OF OPERATIONS (Details)

v2.4.1.9
ORGANIZATION AND NATURE OF OPERATIONS (Details) (USD $)
In Millions, except Share data, unless otherwise specified
3 Months Ended 0 Months Ended 1 Months Ended
Mar. 31, 2015
Apr. 28, 2015
May 18, 2015
Dec. 31, 2014
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]        
Number of self storage properties owned 225us-gaap_NumberOfRealEstateProperties      
Number of states that self storage properties are owned in 13us-gaap_NumberOfStatesInWhichEntityOperates      
Rentable square feet in self storage properties 12,400,000us-gaap_NetRentableArea      
Number of storage units owned 100,000nsa_NumberofStorageUnits      
Number of participating regional operators 5nsa_NumberOfBusinessesOperatedByAffiliates      
National Storage Affiliates Holdings LLC [Member] | National Storage Affiliates Trust [Member]        
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]        
Percentage of NSA owned by NSA Holdings 100.00%nsa_InvestmentOwnershipPercentage
/ dei_LegalEntityAxis
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National Storage Affiliates Holdings LLC [Member] | National Storage Affiliates Trust [Member] | Common Shares [Member]        
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]        
Shares owned by NSA Holdings (in shares) 1,000us-gaap_InvestmentOwnedBalanceShares
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommonStockMember
/ dei_LegalEntityAxis
= nsa_NationalStorageAffiliatesHoldingsLLCMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= nsa_NationalStorageAffiliatesTrustMember
     
National Storage Affiliates Holdings LLC [Member] | NSA OP, LP [Member] | OP units [Member]        
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]        
Shares owned by NSA Holdings (in shares) 126,400us-gaap_InvestmentOwnedBalanceShares
/ us-gaap_InvestmentTypeAxis
= nsa_ClassAUnitsMember
/ dei_LegalEntityAxis
= nsa_NationalStorageAffiliatesHoldingsLLCMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= nsa_NSAOPLPMember
    126,400us-gaap_InvestmentOwnedBalanceShares
/ us-gaap_InvestmentTypeAxis
= nsa_ClassAUnitsMember
/ dei_LegalEntityAxis
= nsa_NationalStorageAffiliatesHoldingsLLCMember
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= nsa_NSAOPLPMember
Subsequent Event [Member] | Common Shares [Member] | IPO [Member]        
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]        
Shares offered including underwriters option   20,000,000us-gaap_StockIssuedDuringPeriodSharesNewIssues
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/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_IPOMember
   
Total net proceeds from initial public offering   $ 236.4us-gaap_ProceedsFromIssuanceInitialPublicOffering
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_CommonStockMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
/ us-gaap_SubsidiarySaleOfStockAxis
= us-gaap_IPOMember
   
Subsequent Event [Member] | National Storage Affiliates Holdings LLC [Member] | National Storage Affiliates Trust [Member] | Common Shares [Member]        
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]        
Shares owned by NSA Holdings (in shares)   1,000us-gaap_InvestmentOwnedBalanceShares
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommonStockMember
/ dei_LegalEntityAxis
= nsa_NationalStorageAffiliatesHoldingsLLCMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= nsa_NationalStorageAffiliatesTrustMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
   
Common Shares [Member]        
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]        
Common share par value (in dollars per share) 0.01us-gaap_CommonStockNoParValue
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Common Shares [Member] | Subsequent Event [Member]        
Subsidiary of Limited Liability Company or Limited Partnership [Line Items]        
Shares offered including underwriters option     23,000,000us-gaap_StockIssuedDuringPeriodSharesNewIssues
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Total net proceeds from initial public offering     $ 273.0us-gaap_ProceedsFromIssuanceInitialPublicOffering
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