Convertible notes.

No definition available.

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

- Definition

Remaining principal amount of the liability component of convertible debt.

+ References

No definition available.

+ Details

Name:	cdns_RemainingPrincipalAmountOfLiabilityComponentOfConvertibleDebt
Namespace Prefix:	cdns_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Senior note warrants expiration date description.

+ References

No definition available.

+ Details

Name:	cdns_SeniorNoteWarrantsExpirationDateDescription
Namespace Prefix:	cdns_
Data Type:	us-types:dateStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Shares of common stock that can be purchased under warrants.

+ References

No definition available.

+ Details

Name:	cdns_SharesOfCommonStockThatCanBePurchasedUnderWarrants
Namespace Prefix:	cdns_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Warrants to purchase shares of common stock price per share.

+ References

No definition available.

+ Details

Name:	cdns_WarrantsToPurchaseSharesOfCommonStockPricePerShare
Namespace Prefix:	cdns_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(1))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Definition

The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 1A

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of cash paid for interest during the period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4297-108586

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

+ Details

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

- Definition

The cash outflow for derivative instruments during the period, which are classified as financing activities, excluding those designated as hedging instruments.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 23

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3505-108585

+ Details

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

- Definition

The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination.

+ References

No definition available.

+ Details

Name:	us-gaap_ProceedsFromDebtNetOfIssuanceCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow provided by derivative instruments during the period, which are classified as financing activities, excluding those designated as hedging instruments.

+ References

+ Details

Name:	us-gaap_ProceedsFromDerivativeInstrumentFinancingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from issuance of rights to purchase common shares at predetermined price (usually issued together with corporate debt).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 14

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3255-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfWarrants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow from the repayment of a long-term debt instrument which can be exchanged for a specified amount of another security, typically the entity's common stock, at the option of the issuer or the holder.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3291-108585

+ Details

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

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

+ Details

Name:	us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cdns_ConvertibleSeniorNotesDue2015Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=cdns_SeniorNotesDueTwentyTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (Details Textual) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		1 Months Ended	6 Months Ended
	Oct. 09, 2014	Jun. 30, 2010	Jul. 04, 2015	Jun. 28, 2014	Jan. 03, 2015
Debt Instrument [Line Items]
Payments of convertible notes			$ 349,999	$ 0
Cash paid for interest			(12,006)	(4,831)
Unamortized discount			1,267		$ 8,824
Convertible Notes (Textual) [Abstract]
Payment of convertible notes embedded conversion derivative liability			(530,643)	0
Proceeds from from convertible notes hedges			$ 530,643	$ 0
Senior Notes [Member] \| Convertible Senior Notes Due 2015 [Member]
Debt Instrument [Line Items]
Aggregate principal amount, issued		$ 350,000
Stated interest rate of Senior Notes			2.625%
Payments of convertible notes			$ 350,000
Cash paid for interest			(3,800)
Unamortized discount			0		7,500
Convertible Notes (Textual) [Abstract]
Principal amount outstanding			$ 0		349,999
Warrants to purchase shares of common stock price per share (in usd per share)			$ 10.78
Payment of convertible notes embedded conversion derivative liability			$ (530,600)
Proceeds from from convertible notes hedges			$ 530,600
Shares of common stock that can be purchased under warrants (in shares)			46.4
Amount received in cash proceeds from the sale of warrants		$ 37,500
Notes Warrants expiration date description			daily over a 70-day period between September and December 2015
Senior Notes [Member] \| Senior Notes Due 2024 [Member]
Debt Instrument [Line Items]
Aggregate principal amount, issued	$ 350,000		$ 350,000		350,000
Stated interest rate of Senior Notes	4.375%
Proceeds from Senior Notes, net	$ 342,400
Unamortized discount	1,400		$ 1,267		$ 1,324
Debt issuance costs	$ 6,200