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) - USD ($)		3 Months Ended
DEBT FINANCING - Narrative (Details) - USD ($)	Jan. 29, 2018	Mar. 31, 2018
Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 1,300,000,000
Unsecured Debt \| Amended Credit Facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 1,000,000,000
Unsecured Debt \| Amended Credit Facility \| Term loan A
Debt Instrument [Line Items]
Maximum borrowing capacity	235,000,000
Unsecured Debt \| Amended Credit Facility \| Term loan B
Debt Instrument [Line Items]
Maximum borrowing capacity	155,000,000
Unsecured Debt \| Amended Credit Facility \| Term loan C
Debt Instrument [Line Items]
Maximum borrowing capacity	105,000,000
Unsecured Debt \| Amended Credit Facility \| Term loan D
Debt Instrument [Line Items]
Term loan D principal amount	125,000,000
Maximum borrowing capacity	125,000,000
Credit facility expansion partial exercise	20,000,000
Unsecured Debt \| Credit Facility \| Term loan D \| Federal Funds Effective Swap Rate
Debt Instrument [Line Items]
Borrowing rate spread (percent)		0.50%
Unsecured Debt \| Credit Facility \| Term loan D \| LIBOR
Debt Instrument [Line Items]
Borrowing rate spread (percent)		1.00%
Unsecured Debt \| Credit Facility \| Term loan D \| Minimum \| LIBOR
Debt Instrument [Line Items]
Leverage based margin threshold (percent)		1.30%
Elective leverage based margin threshold (percent)		0.90%
Unsecured Debt \| Credit Facility \| Term loan D \| Minimum \| Base Rate
Debt Instrument [Line Items]
Leverage based margin threshold (percent)		0.30%
Elective leverage based margin threshold (percent)		0.00%
Unsecured Debt \| Credit Facility \| Term loan D \| Maximum \| LIBOR
Debt Instrument [Line Items]
Leverage based margin threshold (percent)		1.85%
Elective leverage based margin threshold (percent)		1.75%
Unsecured Debt \| Credit Facility \| Term loan D \| Maximum \| Base Rate
Debt Instrument [Line Items]
Leverage based margin threshold (percent)		0.85%
Elective leverage based margin threshold (percent)		0.75%
Unsecured Debt \| Expansion Option of Amended Credit Facility
Debt Instrument [Line Items]
Credit facility expansion option	300,000,000
Line of Credit \| Amended Credit Facility \| Revolving line of credit
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 400,000,000
Line of Credit \| Credit Facility \| Revolving line of credit
Debt Instrument [Line Items]
Revolving line of credit remaining borrowing capacity		$ 322,700,000
Line of Credit \| Credit Facility \| Letter of credit
Debt Instrument [Line Items]
Letters of credit outstanding		$ 4,700,000