Interim Statement Presentation (Details) $ in Millions	9 Months Ended
Sep. 30, 2020 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
CARES Act Deferred Remittance of Employer Payroll Tax	$ 56

CARES Act Deferred Remittance of Employer Payroll Tax

No definition available.

Name:	cern_CARESActDeferredRemittanceOfEmployerPayrollTax
Namespace Prefix:	cern_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration