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SHARE-BASED COMPENSATION PLANS (Details) (USD $)
In Millions, except Share data, unless otherwise specified
0 Months Ended 12 Months Ended 0 Months Ended
May 30, 2012
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Jan. 24, 2014
Jan. 25, 2013
Jan. 25, 2012
Chief executive officer                
Share options, additional general disclosures                
Aggregate grant date fair value of share based awards issued (in dollars) $ 3.0cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardShareBasedAwardsGrantsInPeriodAggregateGrantDateFairValue
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ChiefExecutiveOfficerMember
             
Number of Non-Vested Restricted Shares                
Granted (in shares) 274,668us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ChiefExecutiveOfficerMember
             
Restricted share, additional disclosure                
Period for calculation of total return to shareholders 2 years              
Share Options                
Assumptions used for estimating the fair value of share options using the Black-Scholes option-pricing model                
Risk-free interest rate (as a percent)   1.90%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
2.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Expected dividend yield (as a percent)   3.20%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
3.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
4.50%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Volatility (as a percent)   37.98%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
42.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
52.22%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Weighted average expected life of the options   6 years 6 years 9 years 7 months 2 days        
Weighted average grant date fair value of options granted per share (in dollars per share)   $ 4.33us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 4.28us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 3.94us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Share options, additional general disclosures                
Compensation expense recognized (in dollars)   0.9us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
0.9us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1.2us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Aggregate grant date fair value of share based awards issued (in dollars)   1.0cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardShareBasedAwardsGrantsInPeriodAggregateGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
           
Unrecognized compensation cost   1.0us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
           
Unrecognized compensation cost recorded, period   3 years            
Number of Shares Under Option                
Balance at the beginning of the period (in shares)   4,904,613us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
5,257,864us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
5,255,718us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Options granted (in shares)   223,590us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
182,297us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
222,421us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Options canceled (in shares)   (10,731)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(24,000)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(10,375)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Options exercised (in shares)   (1,425,171)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(511,548)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(209,900)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Balance at the end of the period (in shares)   3,692,301us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
4,904,613us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
5,257,864us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
5,255,718us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Vested or expected to vest at the end of the period (in shares)   3,692,301us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
           
Exercisable at the end of the period (in shares)   3,271,474us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
           
Weighted Average Exercise Price                
Balance at the beginning of the period (in dollars per share)   $ 10.99us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 10.50us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 10.35us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Options granted (in dollars per share)   $ 15.73us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 14.84us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 11.48us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Options canceled (in dollars per share)   $ 17.38us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 13.57us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 9.01us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Options exercised (in dollars per share)   $ 9.69us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 7.24us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 7.89us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
       
Balance at the end of the period (in dollars per share)   $ 11.76us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 10.99us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 10.50us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 10.35us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Exercisable at the end of the period (in dollars per share)   $ 11.37us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
           
Vested or expected to vest at the end of the period (in dollars per share)   $ 11.76us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
           
Weighted Average Remaining Contractual Term                
Balance at the beginning of the period   4 years 1 month 28 days 4 years 7 months 28 days 5 years 5 months 27 days 6 years 3 months 29 days      
Options granted   9 years 29 days 9 years 29 days 9 years 1 month 21 days        
Options exercised   3 years 2 months 16 days 4 years 6 months 11 days 6 years 29 days        
Balance at the end of the period   4 years 1 month 28 days 4 years 7 months 28 days 5 years 5 months 27 days 6 years 3 months 29 days      
Vested or expected to vest at the end of the period   4 years 1 month 28 days            
Exercisable at the end of the period   3 years 7 months 6 days            
Aggregate intrinsic value                
Options, vested or expected to vest and exercisable (in dollars)   38.1cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAndExercisableAggregateIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
           
Options exercised (in dollars)   15.5us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
           
Share Options | Minimum                
Share options, additional general disclosures                
Vesting period   3 years            
Restricted Shares                
Share options, additional general disclosures                
Compensation expense recognized (in dollars)   3.5us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
5.4us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
3.9us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
       
Aggregate grant date fair value of share based awards issued (in dollars)   3.4cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardShareBasedAwardsGrantsInPeriodAggregateGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
3.4cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardShareBasedAwardsGrantsInPeriodAggregateGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
         
Unrecognized compensation cost   3.0us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
           
Unrecognized compensation cost recorded, period   4 years            
Number of Non-Vested Restricted Shares                
Non-vested at the beginning of the period (in shares)   711,631us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
           
Granted (in shares)   194,495us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
219,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
         
Vested (in shares)   (523,700)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
           
Forfeited (in shares)   (1,643)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
           
Non-vested at the end of the period (in shares)   380,783us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
711,631us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
         
Restricted Shares | Minimum                
Share options, additional general disclosures                
Vesting period   3 years            
Restricted Shares | Maximum                
Share options, additional general disclosures                
Vesting period   5 years            
Restricted share units                
Share options, additional general disclosures                
Aggregate grant date fair value of share based awards issued (in dollars)           $ 0.9cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardShareBasedAwardsGrantsInPeriodAggregateGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
$ 0.8cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardShareBasedAwardsGrantsInPeriodAggregateGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
$ 0.8cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardShareBasedAwardsGrantsInPeriodAggregateGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
Number of Non-Vested Restricted Shares                
Granted (in shares)           47,487us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
41,503us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
49,981us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockUnitsRSUMember
Restricted share, additional disclosure                
Period for calculation of total return to shareholders           3 years 3 years 3 years
Plans | Share Options | Maximum                
SHARE-BASED COMPENSATION PLANS                
Maximum term of options   10 years            
2007 Plan                
SHARE-BASED COMPENSATION PLANS                
Maximum number of fungible units available for issuance (in shares)   4,728,561cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfFungibleUnitsAuthorized
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
           
Additional fungible units available for grant upon expiration or forfeiture of options and restricted share awards   372,135cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardAdditionalNumberOfFungibleUnitsAvailableForGrant
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
           
Number of ratios used to establish an average   3cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardAverageNumberOfRatios
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
           
Maximum percentage limit of the average of three ratios   2.00%cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumRatiosLimit
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
           
Maximum number of awards that may be granted to an individual per calendar year (in shares)   1,000,000cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfAwardsPerEmployeePlanLimit
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
           
2007 Plan | Minimum                
SHARE-BASED COMPENSATION PLANS                
Share awards conversion ratio to be counted as units against the fungible pool limit     1.0cube_ShareBasedCompensationArrangementByShareBasedPaymentsSharesConvertedToFungiblePoolUnits
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
         
2007 Plan | Maximum                
SHARE-BASED COMPENSATION PLANS                
Share awards conversion ratio to be counted as units against the fungible pool limit     1.66cube_ShareBasedCompensationArrangementByShareBasedPaymentsSharesConvertedToFungiblePoolUnits
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
         
2007 Plan | Options or share appreciation rights                
SHARE-BASED COMPENSATION PLANS                
Share awards conversion ratio to be counted as units against the fungible pool limit   1.00cube_ShareBasedCompensationArrangementByShareBasedPaymentsSharesConvertedToFungiblePoolUnits
/ us-gaap_AwardTypeAxis
= cube_EmployeeStockOptionAndStockAppreciationRightsMember
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
           
2007 Plan | Restricted shares or restricted share units                
SHARE-BASED COMPENSATION PLANS                
Share awards conversion ratio to be counted as units against the fungible pool limit   1.66cube_ShareBasedCompensationArrangementByShareBasedPaymentsSharesConvertedToFungiblePoolUnits
/ us-gaap_AwardTypeAxis
= cube_RestrictedStockMemberAndRestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
           
2007 Plan | Restricted Shares                
SHARE-BASED COMPENSATION PLANS                
Numerator used to expand the number of Full-Value awards   1.5cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesOfRatiosNumeratorFullValueAwards
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_PlanNameAxis
= cube_Plan2007Member
           
2004 Plan                
SHARE-BASED COMPENSATION PLANS                
Maximum number of shares reserved for issuance   3,000,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_PlanNameAxis
= cube_Plan2004Member
           
2004 Plan | Options or share appreciation rights                
SHARE-BASED COMPENSATION PLANS                
Maximum number of awards that may be granted to an individual per calendar year (in shares)   400,000cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfAwardsPerEmployeePlanLimit
/ us-gaap_AwardTypeAxis
= cube_EmployeeStockOptionAndStockAppreciationRightsMember
/ us-gaap_PlanNameAxis
= cube_Plan2004Member
           
2004 Plan | Restricted shares or restricted share units                
SHARE-BASED COMPENSATION PLANS                
Maximum number of awards that may be granted to an individual per calendar year (in shares)   100,000cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfAwardsPerEmployeePlanLimit
/ us-gaap_AwardTypeAxis
= cube_RestrictedStockMemberAndRestrictedStockUnitsRSUMember
/ us-gaap_PlanNameAxis
= cube_Plan2004Member
           
2004 Plan | Other awards                
SHARE-BASED COMPENSATION PLANS                
Maximum number of awards that may be granted to an individual per calendar year (in shares)   250,000cube_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumNumberOfAwardsPerEmployeePlanLimit
/ us-gaap_AwardTypeAxis
= cube_OtherEquityAwardsMember
/ us-gaap_PlanNameAxis
= cube_Plan2004Member