EARNINGS PER SHARE - Schedule of the Computation of Basic and Diluted Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Numerator
Net income	$ 116,274	$ 183,270	$ 236,988
Net income attributable to noncontrolling interests	(42,490)	(71,752)	(80,319)
Net income attributable to National Storage Affiliates Trust	73,784	111,518	156,669
Distributions to preferred shareholders	(20,462)	(20,445)	(19,019)
Distributed and undistributed earnings allocated to participating securities	(55)	(45)	(57)
Net income attributable to common shareholders - basic	53,267	91,028	137,593
Effect of assumed conversion of dilutive securities	0	0	78,196
Net income attributable to common shareholders - diluted	$ 53,267	$ 91,028	$ 215,789
Denominator
Weighted average shares outstanding - basic (in shares)	76,638	76,844	86,846
Effect of dilutive securities:
Weighted average OP units outstanding (in shares)	0	0	38,302
Weighted average DownREIT OP unit equivalents outstanding (in shares)	0	0	2,120
Weighted average LTIP units outstanding (in shares)	0	0	60
Weighted average subordinated performance units and DownREIT Subordinated performance unit equivalents (in shares)	0	0	18,695
Weighted average shares outstanding - diluted (in shares)	76,638	76,844	146,023
Earnings per share - basic (in dollars per share)	$ 0.69	$ 1.18	$ 1.58
Earnings per share - diluted (in dollars per share)	0.69	1.18	1.48
Dividends declared per common share (in dollars per share)	$ 2.28	$ 2.25	$ 2.23