Quarterly report pursuant to Section 13 or 15(d)

RELATED PARTY TRANSACTIONS (Details)

v2.4.1.9
RELATED PARTY TRANSACTIONS (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
0 Months Ended 1 Months Ended 3 Months Ended 2 Months Ended 12 Months Ended 0 Months Ended
Jan. 01, 2015
property
Jan. 31, 2015
property
Mar. 31, 2015
property
Mar. 31, 2014
May 31, 2015
property
Dec. 31, 2014
property
Apr. 01, 2015
Jul. 01, 2014
Related Party Transaction [Line Items]                
Property operating expenses     $ 9,842us-gaap_CostOfRealEstateRevenue $ 4,922us-gaap_CostOfRealEstateRevenue        
General and administrative expenses     3,613us-gaap_GeneralAndAdministrativeExpense 1,338us-gaap_GeneralAndAdministrativeExpense        
Note receivable from PRO     0us-gaap_NotesReceivableRelatedParties     1,778us-gaap_NotesReceivableRelatedParties    
Loan receivable settled in self storage property acquisition     1,778nsa_BusinessCombinationConsiderationTransferredNotesReceivable          
Number of self storage properties acquired 5us-gaap_NumberOfBusinessesAcquired 6us-gaap_NumberOfBusinessesAcquired 6us-gaap_NumberOfBusinessesAcquired          
Subsequent Event [Member]                
Related Party Transaction [Line Items]                
Number of self storage properties acquired         21us-gaap_NumberOfBusinessesAcquired
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
     
Participating Regional Operator [Member] | Management [Member]                
Related Party Transaction [Line Items]                
Note receivable from PRO               8,000us-gaap_NotesReceivableRelatedParties
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
Loan receivable settled in self storage property acquisition           6,200nsa_BusinessCombinationConsiderationTransferredNotesReceivable
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
   
Number of self storage properties acquired   2us-gaap_NumberOfBusinessesAcquired
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
      13us-gaap_NumberOfBusinessesAcquired
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
   
Supervisory and Administrative Fee Agreement [Member] | Participating Regional Operator [Member] | Management [Member]                
Related Party Transaction [Line Items]                
General and administrative expenses     1,600us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RelatedPartyTransactionAxis
= nsa_SupervisoryandAdministrativeFeeAgreementMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
800us-gaap_GeneralAndAdministrativeExpense
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RelatedPartyTransactionAxis
= nsa_SupervisoryandAdministrativeFeeAgreementMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
       
Supervisory and Administrative Fee Agreement [Member] | Participating Regional Operator [Member] | Minimum [Member] | Management [Member]                
Related Party Transaction [Line Items]                
Fee agreement on gross revenue, percent     5.00%nsa_RelatedPartyTransactionManagementAgreementPercentOfRevenue
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
/ us-gaap_RelatedPartyTransactionAxis
= nsa_SupervisoryandAdministrativeFeeAgreementMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
         
Supervisory and Administrative Fee Agreement [Member] | Participating Regional Operator [Member] | Maximum [Member] | Management [Member]                
Related Party Transaction [Line Items]                
Fee agreement on gross revenue, percent     6.00%nsa_RelatedPartyTransactionManagementAgreementPercentOfRevenue
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
/ us-gaap_RelatedPartyTransactionAxis
= nsa_SupervisoryandAdministrativeFeeAgreementMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
         
Payroll Services [Member] | Participating Regional Operator [Member] | Management [Member]                
Related Party Transaction [Line Items]                
Property operating expenses     2,900us-gaap_CostOfRealEstateRevenue
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RelatedPartyTransactionAxis
= nsa_PayrollServicesMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
1,500us-gaap_CostOfRealEstateRevenue
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RelatedPartyTransactionAxis
= nsa_PayrollServicesMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember
       
Call Center Services [Member] | SecuCare Self Storage Inc. [Member] | Affiliated Entity [Member]                
Related Party Transaction [Line Items]                
Property operating expenses     200us-gaap_CostOfRealEstateRevenue
/ us-gaap_CounterpartyNameAxis
= nsa_SecuCareSelfStorageInc.Member
/ us-gaap_RelatedPartyTransactionAxis
= nsa_CallCenterServicesMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_AffiliatedEntityMember
100us-gaap_CostOfRealEstateRevenue
/ us-gaap_CounterpartyNameAxis
= nsa_SecuCareSelfStorageInc.Member
/ us-gaap_RelatedPartyTransactionAxis
= nsa_CallCenterServicesMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_AffiliatedEntityMember
       
Area occupied by related party     1,500us-gaap_AreaOfRealEstateProperty
/ us-gaap_CounterpartyNameAxis
= nsa_SecuCareSelfStorageInc.Member
/ us-gaap_RelatedPartyTransactionAxis
= nsa_CallCenterServicesMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_AffiliatedEntityMember
         
Annual rent     25nsa_LessorLeasingArrangementsOperatingLeasesTermOfContractAnnualizedBaseRent
/ us-gaap_CounterpartyNameAxis
= nsa_SecuCareSelfStorageInc.Member
/ us-gaap_RelatedPartyTransactionAxis
= nsa_CallCenterServicesMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_AffiliatedEntityMember
         
Call Center [Member] | Call Center Services [Member] | SecuCare Self Storage Inc. [Member] | Affiliated Entity [Member] | Subsequent Event [Member]                
Related Party Transaction [Line Items]                
Issuance of OP units and subordinated performance units for acquisition of call center             50,000nsa_NoncashOrPartNoncashAcquisitionNoncashFinancialOrEquityInstrumentConsiderationUnitsIssued
/ us-gaap_CounterpartyNameAxis
= nsa_SecuCareSelfStorageInc.Member
/ us-gaap_NoncashOrPartNoncashAcquisitionsByUniqueDescriptionAxis
= nsa_CallCenterMember
/ us-gaap_RelatedPartyTransactionAxis
= nsa_CallCenterServicesMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_AffiliatedEntityMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
 
Other assets, net [Member] | Participating Regional Operator [Member] | Management [Member]                
Related Party Transaction [Line Items]                
Note receivable from PRO           $ 1,800us-gaap_NotesReceivableRelatedParties
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherAssetsMember
/ us-gaap_CounterpartyNameAxis
= nsa_ParticipatingRegionalOperatorMember
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= us-gaap_ManagementMember