NONCONTROLLING INTERESTS - Operating Partnership Ownership (Details) - USD ($) $ in Thousands						12 Months Ended
	Dec. 16, 2019	Jul. 23, 2018	Jan. 31, 2018	May 09, 2017	Apr. 12, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Partnership Ownership
OP Units outstanding which are not owned by the general partner (as a percent)						1.00%	1.00%
Elimination of noncontrolling interest in subsidiaries due to acquisition						$ 40,605		$ 9,033
Adjustment for noncontrolling interest in the Operating Partnership						$ (5,918)	$ (299)	(3,965)
California
Operating Partnership Ownership
OP units issued (in shares)	106,738
Issuance of OP Shares	$ 3,600
Total consideration	18,500
Cash paid for acquisition	$ 14,900
Illinois
Operating Partnership Ownership
Total consideration					$ 11,200
Cash paid for acquisition					$ 9,700			$ 9,700
Units issued (in shares)		46,322						58,400
Maryland
Operating Partnership Ownership
Total consideration				$ 18,200
Amount of mortgage loan commitment				$ 5,900
Units issued (in shares)				440,160
Units issued				$ 12,300
Texas
Operating Partnership Ownership
Total consideration			$ 12,200
Cash paid for acquisition			200
Amount of mortgage loan commitment			$ 7,200
Units issued (in shares)			168,011
Units issued			$ 4,800
Capital Unit Class C | Illinois
Operating Partnership Ownership
Units redeemed		58,400
Units issued (in shares)		46,322			58,400
Cubesmart, L P and Subsidiaries
Operating Partnership Ownership
OP units outstanding (in shares)						1,972,308	1,945,570
Number of trading days used to determine average of the closing prices of the shares						10 days	10 days
Elimination of noncontrolling interest in subsidiaries due to acquisition						$ 40,605	$ 169	$ 9,033
Adjustment for noncontrolling interest in the Operating Partnership						$ (5,918)	$ (299)	$ (3,965)