Represents the fixed charge coverage ratio required by the financial covenant under the terms of the debt agreement.

No definition available.

Name:	cube_DebtInstrumentCovenantFixedChargeCoverageRatio
Namespace Prefix:	cube_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of net proceeds from equity issuances added to the minimum tangible net worth in calculating the financial covenant per the terms of the debt agreement.

+ References

No definition available.

+ Details

Name:	cube_DebtInstrumentCovenantPercentageOfProceedsFromEquityIssuancesAddedToTangibleNetWorth
Namespace Prefix:	cube_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the minimum tangible net worth required by the financial covenant under the terms of the debt agreement.

+ References

No definition available.

+ Details

Name:	cube_DebtInstrumentCovenantTangibleNetWorth
Namespace Prefix:	cube_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the total indebtedness to total asset value coverage ratio required by the financial covenant under the terms of the debt agreement.

+ References

No definition available.

+ Details

Name:	cube_DebtInstrumentCovenantTotalIndebtednessToTotalAssetValueRatio
Namespace Prefix:	cube_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of funds from operations that can be distributed on common shares as a condition under the covenant.

+ References

No definition available.

+ Details

Name:	cube_DebtInstrumentDistributionOnCommonSharesAsPercentageOfFundsFromOperationsCovenantCompliance
Namespace Prefix:	cube_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of unamortized cost written off during the period.

+ References

No definition available.

+ Details

Name:	cube_UnamortizedCostWriteOff
Namespace Prefix:	cube_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of unsecured term loans.

+ References

No definition available.

+ Details

Name:	cube_UnsecuredDebtNet
Namespace Prefix:	cube_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

+ Details

Name:	us-gaap_DeferredFinanceCostsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

Name:	us-gaap_ExtinguishmentOfDebtAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_UnsecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=cube_TermLoanFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cube_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cube_TermLoanOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditRatingMoodysAxis=us-gaap_MoodysBaa2RatingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cube_TermLoanTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cube_CreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cube_UnsecuredCreditFacilityRevolverMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=cube_UnsecuredTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cube_SeniorNotes4.375PercentDueOnDecember152023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cube_SeniorNotes4.00PercentDueOnNovember152025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

REVOLVING CREDIT FACILITY AND UNSECURED TERM LOANS (Details)						12 Months Ended
	Dec. 15, 2017 USD ($)	Nov. 15, 2017 USD ($)	Apr. 06, 2017 USD ($)	Apr. 04, 2017 USD ($)	Jun. 20, 2011 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Apr. 22, 2015 USD ($)
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Loan procurement costs capitalized						$ 21,400,000	$ 24,700,000
Loan procurement costs, net of amortization						1,592,000	2,150,000
Interest rate (as a percent)	4.375%
Unsecured term loan						299,396,000	398,749,000
Less: Loan procurement costs, net						(1,592,000)	(2,150,000)
Term Loan Facility \| Minimum
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Tangible net worth						$ 821,211,200
Term Loan Facility \| Maximum
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Percentage of funds from operations that can be distributed on common shares						95.00%
Term Loan Facility \| Term Loan
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Effective interest rate (as a percent)						3.05%
Term Loan Facility \| Term Loan A
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Maximum borrowing capacity					$ 100,000,000
Term of debt instrument					5 years
Write off of unamortized cost			$ 200,000
Repayment of outstanding debt			$ 100,000,000
Unsecured term loan							100,000,000
Term Loan Facility \| Term Loan A \| Baa2/BBB \| LIBOR
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Interest rate, basis spread (as a percent)						1.30%
Term Loan Facility \| Term Loan B
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Maximum borrowing capacity					$ 100,000,000
Term of debt instrument					7 years
Unsecured term loan						$ 100,000,000	100,000,000
Effective interest rate (as a percent)						3.62%
Term Loan Facility \| Term Loan B \| Baa2/BBB \| LIBOR
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Interest rate, basis spread (as a percent)						1.15%
Credit Facility
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Loan procurement costs, net of amortization						$ 604,000	1,251,000
Unsecured term loan						300,000,000	400,000,000
Less: Loan procurement costs, net						(604,000)	(1,251,000)
Total unsecured term loans, net						$ 299,396,000	398,749,000
Net proceeds from equity issuances added to minimum tangible net worth (as a percent)						75.00%
Credit Facility \| Minimum
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Fixed charge coverage ratio						1.50
Credit Facility \| Maximum
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Total indebtedness to total asset value ratio (as a percent)						60.00%
Credit Facility \| Revolver
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Maximum borrowing capacity								$ 500,000,000
Interest rate, basis spread (as a percent)						1.25%
Facility fee (as a percent)						0.15%
Remaining borrowing capacity						$ 417,600,000
Outstanding letter of credit						700,000
Credit Facility \| Unsecured term loan
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Unsecured term loan						$ 200,000,000	$ 200,000,000
Effective interest rate (as a percent)						2.86%
Senior notes 4.375% due 2023
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Proceeds from senior notes	$ 250,000,000			$ 50,000,000
Interest rate (as a percent)				4.375%		4.375%	4.375%
Effective interest rate (as a percent)						4.33%
Effective weighted average interest rate (as a percent)	4.501%			3.495%		4.33%
Senior notes 4.000% due 2025
SECURED CREDIT FACILITY, UNSECURED CREDIT FACILITY AND SECURED TERM LOANS
Proceeds from senior notes		$ 250,000,000		$ 50,000,000
Interest rate (as a percent)		4.00%		4.00%		4.00%	4.00%
Effective interest rate (as a percent)		4.032%		3.811%		3.99%
Effective weighted average interest rate (as a percent)						3.994%