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

ORGANIZATION AND NATURE OF OPERATIONS (Details) ft² in Millions	Jun. 30, 2019 ft² storage_unit state property
Schedule of Equity Method Investments [Line Items]
Number of self storage properties \| property	729
Number of states in which self storage properties are located \| state	35
Total rentable square feet in self storage properties \| ft²	46.5
Number of storage units \| storage_unit	373,000
Consolidated Properties
Schedule of Equity Method Investments [Line Items]
Number of self storage properties \| property	554
Number of states in which self storage properties are located \| state	29
Total rentable square feet in self storage properties \| ft²	33.8
Number of storage units \| storage_unit	269,000
Unconsolidated Properties \| Corporate Joint Venture
Schedule of Equity Method Investments [Line Items]
Number of self storage properties \| property	175
Number of states in which self storage properties are located \| state	21
Total rentable square feet in self storage properties \| ft²	12.7
Number of storage units \| storage_unit	104,000
Company's equity interest in unconsolidated real estate ventures (percent)	25.00%