EARNINGS PER SHARE AND UNIT AND SHAREHOLDERS' EQUITY AND CAPITAL - Earnings Per Share and Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Basic and diluted earnings per common share
Net income	$ 103,073			$ 113,440			$ 299,298	$ 210,300
Noncontrolling interests in the Operating Partnership	(640)			(733)			(1,870)	(1,404)
Noncontrolling interest in subsidiaries	212			181			662	505
NET INCOME ATTRIBUTABLE TO THE COMPANY'S COMMON SHAREHOLDERS	$ 102,645			$ 112,888			$ 298,090	$ 209,401
Weighted average basic shares outstanding (in shares)	225,467,000			225,023,000			225,380,000	224,883,000
Share options and restricted share units (in shares)	743,000			943,000			826,000	998,000
Weighted-average diluted shares outstanding (in shares)	226,210,000			225,966,000			226,206,000	225,881,000
Basic earnings per share attributable to common shareholders (in dollars per share)	$ 0.46			$ 0.50			$ 1.32	$ 0.93
Diluted earnings per share attributable to common shareholders (in dollars per share)	$ 0.45			$ 0.50			$ 1.32	$ 0.93
Basic and diluted earnings per common unit
Noncontrolling interests in the Operating Partnership	$ (640)			$ (733)			$ (1,870)	$ (1,404)
Weighted average basic shares outstanding (in shares)	225,467,000			225,023,000			225,380,000	224,883,000
Share options and restricted share units (in shares)	743,000			943,000			826,000	998,000
Weighted-average diluted shares outstanding (in shares)	226,210,000			225,966,000			226,206,000	225,881,000
Diluted earnings per share attributable to common shareholders (in dollars per share)	$ 0.45			$ 0.50			$ 1.32	$ 0.93
Potentially dilutive shares not included in the earnings per share calculation as their effect is antidilutive (in shares)	700,000			300,000			700,000	300,000
Common stock, cash dividends declared (in dollars per share)	$ 0.49	$ 0.49	$ 0.49	$ 0.43	$ 0.43	$ 0.43	$ 1.47	$ 1.29
OP units outstanding (in shares)	1,360,549			1,460,520			1,360,549	1,460,520	1,426,549
Common shares, shares outstanding	224,859,021			224,568,376			224,859,021	224,568,376	224,603,462
Operating Partnership [Member]
Basic and diluted earnings per common unit
Potentially dilutive shares not included in the earnings per share calculation as their effect is antidilutive (in shares)	1,400,000			1,500,000			1,400,000	1,500,000
CubeSmart, L.P. and Subsidiaries
Basic and diluted earnings per common share
Net income							$ 299,298	$ 210,300
Noncontrolling interests in the Operating Partnership	$ (640)			$ (733)			$ (1,870)	$ (1,404)
Weighted average basic shares outstanding (in shares)	225,467,000			225,023,000			225,380,000	224,883,000
Share options and restricted share units (in shares)	743,000			943,000			826,000	998,000
Weighted-average diluted shares outstanding (in shares)	226,210,000			225,966,000			226,206,000	225,881,000
Diluted earnings per share attributable to common shareholders (in dollars per share)	$ 0.45			$ 0.50			$ 1.32	$ 0.93
Basic and diluted earnings per common unit
Net Income	$ 103,073			$ 113,440			$ 299,298	$ 210,300
Noncontrolling interests in the Operating Partnership	(640)			(733)			(1,870)	(1,404)
Noncontrolling interest in subsidiaries	212			181			662	505
Net income attributable to common unitholders	$ 102,645			$ 112,888			$ 298,090	$ 209,401
Weighted average basic shares outstanding (in shares)	225,467,000			225,023,000			225,380,000	224,883,000
Share options and restricted share units (in shares)	743,000			943,000			826,000	998,000
Weighted-average diluted shares outstanding (in shares)	226,210,000			225,966,000			226,206,000	225,881,000
Basic earnings per unit attributable to common unitholders (in dollars per share)	$ 0.46			$ 0.50			$ 1.32	$ 0.93
Diluted earnings per share attributable to common shareholders (in dollars per share)	$ 0.45			$ 0.50			$ 1.32	$ 0.93