National Storage Affiliates Trust Quarterly report pursuant to Section 13 or 15(d)

Quarterly report pursuant to Section 13 or 15(d)

DEBT FINANCING - Narrative (Details)

DEBT FINANCING - Narrative (Details) - Subsequent Event Type [Domain]			1 Months Ended		2 Months Ended	3 Months Ended		6 Months Ended
	Jan. 01, 2015 property	Apr. 01, 2014 USD ($) component financial_institution	Jun. 03, 2015 USD ($)	Jan. 31, 2015 property	May. 31, 2015 property	Jun. 30, 2015 USD ($) property	Mar. 31, 2015 USD ($) property	Jun. 30, 2015 USD ($) property	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Debt financing						$ 407,816,000		$ 407,816,000		$ 597,691,000
Number of self storage properties acquired \| property	5			6	21	21	6	27
Liabilities assumed, mortgages						$ 30,547,000	$ 16,442,000	$ 46,989,000
Repayment of long term debt								257,084,000	$ 143,564,000
Line of Credit [Member] \| Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 425,000,000.0
Number of financial institutions in lender agreement \| financial_institution		7
Number of lender agreement components \| component		2
Line of Credit [Member] \| Credit Facility [Member] \| Revolving line of credit [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 280,400,000.0				199,483,000.000		$ 199,483,000.000
Borrowing base calculation, minimum occupancy rate of property		75.00%
Extension fee, percent								0.20%
Repayment of line of credit			$ 96,300,000
Debt financing						$ 80,917,000		$ 80,917,000		166,217,000
Effective interest rate						1.79%		1.79%
Line of Credit [Member] \| Credit Facility [Member] \| Revolving line of credit [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Reduced borrowing rate								1.60%
Line of Credit [Member] \| Credit Facility [Member] \| Revolving line of credit [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Unused borrowing capacity, percent		0.20%
Line of Credit [Member] \| Credit Facility [Member] \| Revolving line of credit [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Unused borrowing capacity, percent		0.30%
Line of Credit [Member] \| Credit Facility [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 144,600,000
Debt financing						$ 144,558,000		$ 144,558,000		144,558,000
Effective interest rate						2.75%		2.75%
Line of Credit [Member] \| Credit Facility [Member] \| Term Loan [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Reduced borrowing rate								1.50%
Loans Payable [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Number of lenders \| financial_institution		3
Debt financing						$ 0		$ 0		50,000,000
Effective interest rate						0.00%		0.00%
Maturity date extension fee								$ 250,000
Repayment of long term debt								50,000,000
Extinguishment of debt, write-off of debt issuance costs								200,000
Loans Payable [Member] \| Unsecured Term Loan [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Reduced borrowing rate		5.00%
Mortgages [Member] \| Fixed Rate Mortgages [Member]
Debt Instrument [Line Items]
Debt financing						$ 182,341,000		$ 182,341,000		153,416,000
Effective interest rate						3.93%		3.93%
Minimum effective interest rate								2.20%
Maximum effective interest rate								5.00%
Number of self storage properties acquired \| property							16
Liabilities assumed, mortgages								$ 47,000,000
Repayment of long term debt								11,000,000
Mortgages [Member] \| Variable Rate Mortgages [Member]
Debt Instrument [Line Items]
Debt financing						$ 0		$ 0		$ 83,500,000
Effective interest rate						0.00%		0.00%
Minimum effective interest rate								2.43%
Maximum effective interest rate								9.65%
Repayment of long term debt								$ 83,500,000
Extinguishment of debt, write-off of debt issuance costs								200,000
Extinguishment of debt, prepayment penalty								$ 500,000