The number of days available for bank renewal of the accounts receivable securitization facility.

No definition available.

Name:	cbb_AccountsReceivableFacilityRenewalTerm
Namespace Prefix:	cbb_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of borrowings outstanding on the accounts receivable securitization facility as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	cbb_ReceivablesFacilityAmountOutstanding
Namespace Prefix:	cbb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The maximum borrowing availability under the accounts receivable securitization facility as of the balance sheet date, based on the quantity and quality of outstanding accounts receivable.

+ References

No definition available.

+ Details

Name:	cbb_ReceivablesFacilityMaximumBorrowingAvailability
Namespace Prefix:	cbb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity of the accounts receivable securitization facility based on the terms of the agreement.

+ References

No definition available.

+ Details

Name:	cbb_ReceivablesFacilityMaximumBorrowingCapacity
Namespace Prefix:	cbb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The remaining borrowing availability under the accounts receivable securitization facility as of the balance sheet date (after subtracting outstanding letters of credit), based on the quantity and quality of outstanding accounts receivable.

+ References

No definition available.

+ Details

Name:	cbb_ReceivablesFacilityRemainingBorrowingCapacity
Namespace Prefix:	cbb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

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 carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ 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))
-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 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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

- Details

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

- Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt - Credit Facility (Details) - USD ($) $ in Millions	3 Months Ended
Debt - Credit Facility (Details) - USD ($) $ in Millions	Jun. 30, 2017	Jun. 30, 2018	Mar. 31, 2018
Line of Credit Facility [Line Items]
Credit Agreement			$ 0.0
Line of Credit Facility, Remaining Borrowing Capacity			200.0
Receivables facility amount outstanding			0.0
Letters of Credit Outstanding, Amount			6.7
Receivables Facility Remaining Borrowing Capacity			92.5
Receivables Facility Maximum Borrowing Availability			99.2
Accounts Receivable Facility, Renewal Term	364
Receivables facility maximum borrowing capacity			$ 120.0
London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			3.75%
Base Rate [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			2.75%
Subsequent Event [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		3.25%
Subsequent Event [Member] \| Base Rate [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.25%