Quarterly report pursuant to Section 13 or 15(d)

SELF STORAGE PROPERTY ACQUISITIONS - Pro Forma Information (Details)

v2.4.1.9
SELF STORAGE PROPERTY ACQUISITIONS - Pro Forma Information (Details) (USD $)
In Thousands, except Per Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Business Combination, Pro Forma Information [Line Items]    
Pro forma revenue $ 31,198us-gaap_BusinessAcquisitionsProFormaRevenue $ 16,964us-gaap_BusinessAcquisitionsProFormaRevenue
Pro forma net income (loss) (992)us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss (4,205)us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
Earnings (loss) per common share (in dollars per share) $ 0.00nsa_BusinessAcquisitionProFormaEarningsPerShareBasicandDiluted $ 0.00nsa_BusinessAcquisitionProFormaEarningsPerShareBasicandDiluted
Pro forma net income (loss) 599us-gaap_BusinessCombinationAcquisitionRelatedCosts 182us-gaap_BusinessCombinationAcquisitionRelatedCosts
April - May 2015 Acquisitions [Member]    
Business Combination, Pro Forma Information [Line Items]    
Pro forma revenue 2,821us-gaap_BusinessAcquisitionsProFormaRevenue
/ us-gaap_BusinessAcquisitionAxis
= nsa_AprilToMay2015AcquisitionsMember
2,586us-gaap_BusinessAcquisitionsProFormaRevenue
/ us-gaap_BusinessAcquisitionAxis
= nsa_AprilToMay2015AcquisitionsMember
Pro forma net income (loss) 888us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
/ us-gaap_BusinessAcquisitionAxis
= nsa_AprilToMay2015AcquisitionsMember
(563)us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
/ us-gaap_BusinessAcquisitionAxis
= nsa_AprilToMay2015AcquisitionsMember
January 2015 Acquisitions [Member]    
Business Combination, Pro Forma Information [Line Items]    
Pro forma revenue 86us-gaap_BusinessAcquisitionsProFormaRevenue
/ us-gaap_BusinessAcquisitionAxis
= nsa_January2015AcquisitionsMember
1,217us-gaap_BusinessAcquisitionsProFormaRevenue
/ us-gaap_BusinessAcquisitionAxis
= nsa_January2015AcquisitionsMember
Pro forma net income (loss) 891us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
/ us-gaap_BusinessAcquisitionAxis
= nsa_January2015AcquisitionsMember
(839)us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
/ us-gaap_BusinessAcquisitionAxis
= nsa_January2015AcquisitionsMember
Consolidated Entities Excluding Acquirees [Member]    
Business Combination, Pro Forma Information [Line Items]    
Pro forma revenue 28,291us-gaap_BusinessAcquisitionsProFormaRevenue
/ dei_LegalEntityAxis
= nsa_ConsolidatedEntitiesExcludingAcquireesMember
13,161us-gaap_BusinessAcquisitionsProFormaRevenue
/ dei_LegalEntityAxis
= nsa_ConsolidatedEntitiesExcludingAcquireesMember
Pro forma net income (loss) $ (2,771)us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
/ dei_LegalEntityAxis
= nsa_ConsolidatedEntitiesExcludingAcquireesMember
$ (2,803)us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss
/ dei_LegalEntityAxis
= nsa_ConsolidatedEntitiesExcludingAcquireesMember
Earnings (loss) per common share (in dollars per share) $ 0.00nsa_BusinessAcquisitionProFormaEarningsPerShareBasicandDiluted
/ dei_LegalEntityAxis
= nsa_ConsolidatedEntitiesExcludingAcquireesMember
$ 0.00nsa_BusinessAcquisitionProFormaEarningsPerShareBasicandDiluted
/ dei_LegalEntityAxis
= nsa_ConsolidatedEntitiesExcludingAcquireesMember
Credit Facility [Member] | Line of Credit [Member] | Revolving line of credit [Member]    
Business Combination, Pro Forma Information [Line Items]    
Effective interest rate 2.78%us-gaap_DebtInstrumentInterestRateEffectivePercentage
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_DebtInstrumentAxis
= nsa_CreditFacilityMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember