National Storage Affiliates Trust Annual report pursuant to Section 13 and 15(d)

ORGANIZATION AND NATURE OF OPERATIONS - Narrative (Details) storage_unit in Thousands, ft² in Millions	12 Months Ended
	Dec. 31, 2021 ft² state property storage_unit metropolitan_statistical_area
Real Estate Properties [Line Items]
Number of top metropolitan statistical areas for focus of operations \| metropolitan_statistical_area	100
Number of self storage properties	1,050
Number of states in which self storage properties are located \| state	42
Total rentable square feet in self storage properties \| ft²	67.8
Number of storage units	533,000
Consolidated properties
Real Estate Properties [Line Items]
Number of self storage properties	873
Number of states in which self storage properties are located \| state	39
Total rentable square feet in self storage properties \| ft²	55.1
Number of storage units \| storage_unit	429
Unconsolidated properties \| Joint Venture
Real Estate Properties [Line Items]
Number of self storage properties	177
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	104,000