Financial Instruments (Available-for-sale Debt Securities) - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Investments Debt And Equity Securities [Abstract]
Available-for-sale securities, debt securities, par value	$ 59.0	$ 55.7
Available-for-sale debt securities, maturity start date	2019-08
Available-for-sale debt securities, maturity end date	2024-02

Available-for-sale securities, debt securities, par value.

No definition available.

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