Name:	ccoi_DebtInstrumentRedemptionPriceDueToChangeOfControlAsPercentageOfPrincipalAmount
Namespace Prefix:	ccoi_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Refers to the accrued interest expense related to the repurchase of debt.

No definition available.

Name:	ccoi_InterestExpenseDebtRelatedToRepurchaseOfDebt
Namespace Prefix:	ccoi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Face (par) amount of debt instrument at time of issuance.

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

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

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

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Name:	us-gaap_DebtInstrumentRedemptionPricePercentage
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Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Amount of gain (loss) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of the cost of borrowed funds accounted for as interest expense for debt.

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

- References

No definition available.