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)				3 Months Ended			9 Months Ended
DEBT FINANCING - Narrative (Details)	Aug. 13, 2015 USD ($)	Jan. 01, 2015 property	Apr. 01, 2014 USD ($) component financial_institution	Sep. 30, 2015 USD ($) property	Jun. 30, 2015 USD ($) property	Mar. 31, 2015 USD ($) property	Sep. 30, 2015 USD ($) property	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Repayment of long term debt							$ 324,247,000	$ 143,634,000
Loss on debt extinguishment							414,000	$ 344,000
Debt financing				$ 495,981,000			495,981,000		$ 597,691,000
Liabilities assumed, mortgages				$ 2,866,000	$ 30,547,000	$ 16,442,000	$ 49,855,000
Number of self storage properties acquired \| property		5		15	21	6	42
Line of Credit [Member] \| Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Increase (Decrease), Net	$ 125,000,000.0
Number of financial institutions in lender agreement \| financial_institution			11
Line of Credit Facility, Current Borrowing Capacity	550,000,000.0
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			$ 350,000,000.0	$ 238,025,000.000			$ 238,025,000.000
Borrowing base calculation, minimum occupancy rate of property			75.00%
Extension fee, percent							0.20%
Debt financing				111,975,000			$ 111,975,000		166,217,000
Line of Credit [Member] \| Credit Facility [Member] \| Revolving line of credit [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Borrowing rate spread							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			0.25%
Line of Credit [Member] \| Credit Facility [Member] \| Term Loan [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity			$ 200,000,000.0
Debt financing				200,000,000			$ 200,000,000		144,558,000
Line of Credit [Member] \| Credit Facility [Member] \| Term Loan [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Borrowing rate spread							1.50%
Line of Credit [Member] \| Amended Credit Facility [Member]
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 700,000,000.0
Loans Payable [Member] \| Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Number of lenders \| financial_institution			3
Repayment of long term debt							$ 50,000,000
Loss on debt extinguishment							200,000
Debt financing				0			0		50,000,000
Maturity date extension fee							250,000
Loans Payable [Member] \| Unsecured Term Loan [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Borrowing rate spread			5.00%
Mortgages [Member] \| Fixed Rate Mortgages [Member]
Debt Instrument [Line Items]
Repayment of long term debt							11,000,000
Debt financing				184,006,000			$ 184,006,000		153,416,000
Minimum effective interest rate							2.20%
Maximum effective interest rate							5.00%
Liabilities assumed, mortgages							$ 49,900,000
Number of self storage properties acquired \| property							17
Mortgages [Member] \| Variable Rate Mortgages [Member]
Debt Instrument [Line Items]
Repayment of long term debt							$ 83,500,000
Loss on debt extinguishment							200,000
Debt financing				$ 0			$ 0		$ 83,500,000
Minimum effective interest rate							2.43%
Maximum effective interest rate							9.65%
Extinguishment of debt, prepayment penalty							$ 500,000