Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Apr. 01, 2017
Americas:
Total Americas	$ 232,469	$ 213,190
Total revenue	517,313	476,911
United States [Member]
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Geographic areas, revenue from external customers	224,803	205,435
Other Americas [Member]
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Geographic areas, revenue from external customers	7,666	7,755
Asia [Member]
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Geographic areas, revenue from external customers	139,947	122,423
EMEA [Member]
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Geographic areas, revenue from external customers	104,708	98,321
Japan [Member]
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Geographic areas, revenue from external customers	$ 40,189	$ 42,977

Entity wide disclosure on geographic areas revenue from external customers attributed to country of domicile and other foreign countries.

No definition available.

+ Details

Name:	cdns_EntityWideDisclosureOnGeographicAreasRevenueFromExternalCustomersAttributedToCountryOfDomicileAndOtherForeignCountries
Namespace Prefix:	cdns_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Entity wide disclosure on geographic areas revenue from external customers attributed to entity's country of domicile and other foreign countries.

+ References

No definition available.

+ Details

Name:	cdns_EntityWideDisclosureOnGeographicAreasRevenueFromExternalCustomersAttributedToEntitysCountryOfDomicileAndOtherForeignCountriesAbstract
Namespace Prefix:	cdns_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

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

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

Name:	us-gaap_Revenues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

+ Details

Name:	us-gaap_SalesRevenueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_StatementGeographicalAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=cdns_OtherAmericaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=us-gaap_AsiaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=us-gaap_EMEAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=country_JP
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: