Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 30, 2013	Mar. 31, 2012
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Total revenue	$ 354,266	$ 315,830
Americas:
United States	149,171	130,455
Total Americas	153,786	138,579
Other Americas [Member]
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Geographic Areas, revenue from External Customers attributed to Individual Foreign Countries	4,615	8,124
Europe, Middle East and Africa [Member]
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Geographic Areas, revenue from External Customers attributed to Individual Foreign Countries	78,920	59,709
Japan [Member]
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Geographic Areas, revenue from External Customers attributed to Individual Foreign Countries	53,474	56,219
Asia [Member]
Entity Wide Disclosure on Geographic Areas Revenue from External Customers
Geographic Areas, revenue from External Customers attributed to Individual Foreign Countries	$ 68,086	$ 61,323

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

No definition available.

+ Details

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Namespace Prefix:	cdns_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Details

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- Definition

Revenues from external customers attributed to the entity's country of domicile.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 41

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 38

-Subparagraph a(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

Revenues from external customers attributed to all foreign countries in total from which the entity derives revenues.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 41

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 38

-Subparagraph a(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- 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

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=6880815&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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