Debt and Financing Arrangements - Additional Information (Detail) - USD ($) $ in Millions		6 Months Ended
Apr. 03, 2018	Jun. 30, 2018
2018 Credit Facility [Member]
Debt Instrument [Line Items]
Credit agreement amendment date	Apr. 03, 2018
Unsecured credit facility	$ 400.0
Extension of maturity date	2023	2019
Revolving loan commitment	$ 400.0
Deferred financing costs		$ 1.1
2014 Credit Facility [Member]
Debt Instrument [Line Items]
Credit agreement amendment date		Jul. 28, 2014
2014 Credit Facility [Member] \| First Amendment [Member]
Debt Instrument [Line Items]
Credit agreement amendment date		Apr. 10, 2015
2014 Credit Facility [Member] \| Second Amendment [Member]
Debt Instrument [Line Items]
Credit agreement amendment date		Nov. 03, 2015

Credit agreement amendment date.

No definition available.

Name:	cbz_CreditAgreementAmendmentDate
Namespace Prefix:	cbz_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of credit facility maturity year.

+ References

No definition available.

+ Details

Name:	cbz_LineOfCreditFacilityMaturityYear
Namespace Prefix:	cbz_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- 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

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

+ Details

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

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Carrying value as of the balance sheet date of uncollateralized debt obligation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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

+ Details

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

- Details

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

- Details

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

- Details

Name:	us-gaap_CreditFacilityAxis=cbz_FirstAmendmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=cbz_SecondAmendmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: