Employee stock purchase plan expiration date.

No definition available.

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

- Definition

Employee stock purchase plan holding period of stock.

+ References

No definition available.

+ Details

Name:	cbz_EmployeeStockPurchasePlanHoldingPeriodOfStock
Namespace Prefix:	cbz_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee stock purchase plan purchase price of shares as a percentage of fair market value of common stock.

+ References

No definition available.

+ Details

Name:	cbz_EmployeeStockPurchasePlanPurchasePriceOfSharesAsPercentageOfFairMarketValueOfCommonStock
Namespace Prefix:	cbz_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee stock purchase plan share purchase maximum authorized amount per employee per year.

+ References

No definition available.

+ Details

Name:	cbz_EmployeeStockPurchasePlanSharePurchaseAuthorizedAmount
Namespace Prefix:	cbz_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Retirement Plans [Line Items]

+ References

No definition available.

+ Details

Name:	cbz_RetirementPlansLineItems
Namespace Prefix:	cbz_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award equity instruments other than options market value.

+ References

No definition available.

+ Details

Name:	cbz_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsMarketValue
Namespace Prefix:	cbz_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award expiration year.

+ References

No definition available.

+ Details

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

- Definition

Share based compensation arrangement by share based payment award number of shares available for future grant.

+ References

No definition available.

+ Details

Name:	cbz_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForFutureGrant
Namespace Prefix:	cbz_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

share based compensation arrangement by share based payment award options purchase price as a percentage of fair value.

+ References

No definition available.

+ Details

Name:	cbz_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsPurchasePriceAsPercentageOfFairValue
Namespace Prefix:	cbz_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award annual vesting percentage.

+ References

No definition available.

+ Details

Name:	cbz_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentage
Namespace Prefix:	cbz_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share-based compensation arrangement by share-based payment award vesting period from grant date.

+ References

No definition available.

+ Details

Name:	cbz_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPeriodFromGrantDate
Namespace Prefix:	cbz_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangements by share based payments award options weighted average fair value at the time of grant date.

+ References

No definition available.

+ Details

Name:	cbz_ShareBasedCompensationArrangementsByShareBasedPaymentsAwardOptionsWeightedAverageFairValueAtTimeOfGrantDate
Namespace Prefix:	cbz_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Share based compensation award equity instruments other than options outstanding release from restriction period range.

+ References

No definition available.

+ Details

Name:	cbz_ShareBasedCompensationAwardEquityInstrumentsOtherThanOptionsOutstandingReleaseFromRestrictionPeriodRange
Namespace Prefix:	cbz_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation share based payments voting power percentage.

+ References

No definition available.

+ Details

Name:	cbz_ShareBasedCompensationShareBasedPaymentsVotingPowerPercentage
Namespace Prefix:	cbz_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

+ References

No definition available.

+ Details

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

- Definition

Unrecognized cost of unvested options awarded to employees as compensation.

+ References

No definition available.

+ Details

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

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

For each plan, identification of the award pricing model or other valuation method used in calculating the weighted average fair values disclosed. The model is also used to calculate the compensation expense that is shown within the balance sheet, income statement, and cash flow. Examples of valuation techniques are lattice models (binomial model), closed-form models (Black-Scholes-Merton formula), and a Monte Carlo simulation technique. Fair value is the amount at which an asset or liability could be bought or incurred or sold or settled in a current transaction between willing parties, that is, other than in a forced or liquidation sale. May include disclosures about the assumptions underlying application of the method selected.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

Number of shares issued during the period as a result of an employee stock purchase plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30
-Article 5

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_RestrictedStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OptionIndexedToIssuersEquityTypeAxis=cbz_EmployeeStockPurchasePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_OptionIndexedToIssuersEquityTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PlanNameAxis=cbz_TwoThousandFourteenStockIncentivePlanMember
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_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Employee Share Plans - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Retirement Plans [Line Items]
Holding period of stock	1 year
Stock awards expiry	2024
Fair value of stock options granted	$ 2.34	$ 2.25	$ 1.96
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Method Used	Black-Scholes-Merton option-pricing model
Options awarded under the plans vesting period	4 years
Restricted Stock Awards [Member]
Retirement Plans [Line Items]
Maximum stock based compensation awards granted under the plan	9,600,000
Compensation cost for non-vested stock options weighted average period	1 year 2 months 12 days
Unrecognized compensation cost for restricted stock awards	$ 7,800,000
Total fair value of shares vested during period	3,100,000	$ 3,500,000	$ 3,000,000
Market value of shares awarded during period	$ 3,300,000	$ 4,100,000	$ 3,400,000
Employee Stock Purchase Plan [Member]
Retirement Plans [Line Items]
Price an employee pays for shares as percentage of fair market value	85.00%
Termination date of the Employee Stock Purchase Plan	Jun. 30, 2017
Stock Option [Member]
Retirement Plans [Line Items]
Percentage of incremental vesting schedule	25.00%	25.00%	25.00%
Incremental vesting schedule period	4 years
Stock options expiry date	6 years
Options awarded under the plans vesting period	4 years
Percentage of option price to fair market value	110.00%
Percentage of voting power of all classes of stock of CBIZ	10.00%
Weighted-average grant-date fair value of stock options granted	$ 2,100,000	$ 3,000,000	$ 3,000,000
Aggregate intrinsic value of stock options exercised	4,600,000	$ 2,300,000	$ 2,000,000
Unrecognized compensation cost for non-vested stock option	$ 5,800,000
Compensation cost for non-vested stock options weighted average period	1 year 3 months 18 days
2014 Stock Incentive Plan [Member]
Retirement Plans [Line Items]
Share available for future grant	9,100,000
Maximum [Member]
Retirement Plans [Line Items]
Shares purchased under ESPP	2,000,000
Restricted stock outstanding release from restriction period range	2016-02
Maximum [Member] \| Restricted Stock Awards [Member]
Retirement Plans [Line Items]
Options awarded under the plans vesting period	4 years
Maximum [Member] \| Employee Stock Purchase Plan [Member]
Retirement Plans [Line Items]
ESPP allows qualified employees to purchase shares of common stock	$ 25,000
Minimum [Member]
Retirement Plans [Line Items]
Restricted stock outstanding release from restriction period range	2019-05
Minimum [Member] \| Restricted Stock Awards [Member]
Retirement Plans [Line Items]
Options awarded under the plans vesting period	1 year