Receivables, net (Details Textual) - Customer	Sep. 26, 2020	Dec. 28, 2019
Receivables [Abstract]
Number of customers with receivables balance greater than ten percent of total balance	0	0
Percentage of receivables, net attributable to single customer	10.00%	10.00%

Number of customers with accounts receivable and installment contract receivable balance greater than ten percent of total balance.

No definition available.

Name:	cdns_NumberOfCustomersWithAccountsReceivableAndInstallmentContractReceivableBalanceGreaterThanTenPercentOfBalance
Namespace Prefix:	cdns_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant