NONCONTROLLING INTERESTS - Operating Partnership Ownership (Details) - USD ($) $ in Thousands			9 Months Ended		12 Months Ended
	Apr. 18, 2016	May 14, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Operating Partnership Ownership
OP Units outstanding which are not owned by the general partner (as a percent)			1.20%		1.20%
OP units issued (in shares)	61,224	20,408
Issuance of OP Units	$ 1,500	$ 500
Increase (decrease) to OP units owned by third parties and a corresponding decrease to capital			$ (6,404)	$ 12,166
CubeSmart, L.P. and Subsidiaries
Operating Partnership Ownership
OP units outstanding (in shares)			2,220,874		2,159,650
Number of trading days used to determine average of the closing prices of the common shares			10 days
Increase (decrease) to OP units owned by third parties and a corresponding decrease to capital			$ (6,404)	$ 12,166	$ (19,600)