Quarterly report pursuant to Section 13 or 15(d)

NONCONTROLLING INTERESTS - Equity Interests (Details)

v2.4.1.9
NONCONTROLLING INTERESTS - Equity Interests (Details)
Mar. 31, 2015
Dec. 31, 2014
Partnership Subsidiaries [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 35,949,747us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_PartnershipSubsidiariesMember 		34,240,410us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_PartnershipSubsidiariesMember
OP units [Member] | NSA OP, LP [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 19,235,556us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_NSAOPLPMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_ClassAUnitsMember 		18,817,088us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_NSAOPLPMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_ClassAUnitsMember
OP units [Member] | DownREIT Partnership [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 1,415,349us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_DownREITPartnershipMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_ClassAUnitsMember 		1,275,979us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_DownREITPartnershipMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_ClassAUnitsMember
Subordinated performance units [Member] | NSA OP, LP [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 8,886,097us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_NSAOPLPMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_ClassBUnitMember 		8,447,679us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_NSAOPLPMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_ClassBUnitMember
Subordinated performance units [Member] | DownREIT Partnership [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 3,688,205us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_DownREITPartnershipMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_ClassBUnitMember 		3,009,884us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_DownREITPartnershipMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_ClassBUnitMember
LTIP units [Member] | NSA OP, LP [Member]    
Noncontrolling Interest [Line Items]    
Outstanding equity interest (in shares) 2,724,540us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_NSAOPLPMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_LongTermIncentivePlanUnitMember 		2,689,780us-gaap_LimitedPartnersCapitalAccountUnitsOutstanding
/ dei_LegalEntityAxis
= nsa_NSAOPLPMember
/ us-gaap_LimitedPartnersCapitalAccountByClassAxis
= nsa_LongTermIncentivePlanUnitMember