SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reclassifications (Details) - USD ($) $ in Thousands |
9 Months Ended | |
|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
|
| New Accounting Pronouncements or Change in Accounting Principle [Line Items] | ||
| Cash paid upon vesting of restricted shares | $ (2,034) | $ (1,631) |
| Accounting Standards Update 2016-09 | Reclassifications | ||
| New Accounting Pronouncements or Change in Accounting Principle [Line Items] | ||
| Cash paid upon vesting of restricted shares | 1,600 | |
| CubeSmart, L.P. and Subsidiaries | ||
| New Accounting Pronouncements or Change in Accounting Principle [Line Items] | ||
| Cash paid upon vesting of restricted shares | $ (2,034) | $ (1,631) |