Accumulated Other Comprehensive Loss - Components of Accumulated Other Comprehensive Loss (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income Loss Net Of Tax [Abstract]
Unrealized gains (losses) on available for sale securities, income tax (benefit) expense	$ 157	$ 129
Unrealized gain on interest rate swaps, income tax expense	$ 419	$ 196

Accumulated Other Comprehensive Income Unrealized Holding Gain Loss On Derivatives Arising During Period Tax

No definition available.

Name:	cbz_AccumulatedOtherComprehensiveIncomeUnrealizedHoldingGainLossOnDerivativesArisingDuringPeriodTax
Namespace Prefix:	cbz_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant