Revenue (Details Textuals) $ in Millions	3 Months Ended	9 Months Ended
Sep. 29, 2018 USD ($)	Sep. 29, 2018 USD ($)
Revenue from Contract with Customer [Abstract]
Percentage of revenue mix recognizable over time	90.00%	90.00%
Revenue recognized from deferred revenue during the period	$ 39.9	$ 250.2
Unsatisfied performance obligations	$ 2,400.0	$ 2,400.0
Percent of remaining performance obligations, current	60.00%	60.00%
Revenue recognized from satisfaction of performance obligations	$ 10.8	$ 25.3
Capitalized contract costs, net	22.1	22.1
Amortization of capitalized contract costs	$ 5.8	$ 16.9

Percentage of Revenue Mix Recognizable Over Time

No definition available.

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- Definition

Percent of remaining performance obligation to be recognized in next twelve months.

+ References

No definition available.

+ Details

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- Definition

Revenue Recognized from Satisfaction of Performance Obligations

+ References

No definition available.

+ Details

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Namespace Prefix:	cdns_
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- Definition

Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054

+ Details

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- Definition

Amount, after accumulated amortization and accumulated impairment loss, of asset recognized from cost incurred to obtain or fulfill contract with customer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68051541&loc=SL49131252-203054

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- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

+ Details

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- References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130556-203045

+ Details

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