EARNINGS PER SHARE - Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Numerator
Net income	$ 29,771	$ 32,280	$ 95,088	$ 43,064	$ 45,476	$ 40,392	$ 157,139	$ 128,932
Net income attributable to noncontrolling interests	(11,070)			(13,827)			(62,349)	(41,290)
Net income attributable to National Storage Affiliates Trust	18,701			29,237			94,790	87,642
Distributions to preferred shareholders	(5,112)			(5,110)			(15,332)	(13,908)
Distributed and undistributed earnings allocated to participating securities	(9)			(13)			(34)	(44)
Net income attributable to common shareholders - basic	13,580			24,114			79,424	73,690
Effect of assumed conversion of dilutive securities	0			13,396			0	40,012
Net income attributable to common shareholders - diluted	$ 13,580			$ 37,510			$ 79,424	$ 113,702
Denominator
Weighted average shares outstanding - basic (in shares)	75,760			87,004			77,047	88,263
Weighted average OP units outstanding (in shares)	0			38,030			0	38,505
Weighted average DownREIT OP unit equivalents outstanding (in shares)	0			2,121			0	2,121
Weighted average LTIP units outstanding (in shares)	0			61			0	54
Weighted average subordinated performance units and DownREIT subordinated performance unit equivalents (in shares)	0			18,902			0	18,667
Weighted average shares outstanding - diluted (in shares)	75,760			146,118			77,047	147,610
Earnings per share - basic (in dollars per share)	$ 0.18			$ 0.28			$ 1.03	$ 0.83
Earnings per share - diluted (in dollars per share)	$ 0.18			$ 0.26			$ 1.03	$ 0.77