Convertible Notes (Details Textual) (USD $)	9 Months Ended			9 Months Ended			1 Months Ended	9 Months Ended	12 Months Ended	1 Months Ended	3 Months Ended	9 Months Ended				3 Months Ended	9 Months Ended
	Oct. 02, 2010	Oct. 01, 2011	Jan. 01, 2011	Oct. 01, 2011 Notes Due 2011 [Member]	Oct. 02, 2010 Notes Due 2011 [Member]	Dec. 31, 2006 Notes Due 2011 [Member]	Dec. 31, 2006 Notes Due 2011 [Member] Notes Due 2013 [Member]	Oct. 01, 2011 Notes Due 2011 [Member] Notes Due 2013 [Member]	Jan. 01, 2011 Notes Due 2011 [Member] Notes Due 2013 [Member]	Jun. 30, 2010 Convertible Senior Notes Due 2015 [Member]	Oct. 01, 2011 Convertible Senior Notes Due 2015 [Member]	Oct. 01, 2011 Convertible Senior Notes Due 2015 [Member]	Jan. 01, 2011 Convertible Senior Notes Due 2015 [Member]	Oct. 01, 2011 Zero Coupon Zero Yield Senior Convertible Notes Due 2023 [Member]	Aug. 31, 2003 Zero Coupon Zero Yield Senior Convertible Notes Due 2023 [Member]	Jan. 01, 2011 Notes Due 2013 [Member]	Oct. 01, 2011 Notes Due 2013 [Member]	Oct. 02, 2010 Notes Due 2013 [Member]	Dec. 31, 2006 Notes Due 2013 [Member]
Convertible Notes (Textual) [Abstract]
Stated interest rate of Convertible Senior Notes				1.375%							2.625%	2.625%					1.50%
Maturity date of Convertible Senior Notes				Dec. 15, 2011								Jun. 01, 2015					Dec. 15, 2013
Interest rate payable term for Convertible Senior Notes								semi-annually each December 15th and June 15th				semi-annually each December 1st and June 1st
Event 1								During any calendar quarter, and only during such calendar quarter, if the closing price of Cadence’s common stock exceeds $27.50 for 20 or more of the final 30 trading days in the preceding calendar quarter;				During any fiscal quarter, and only during such fiscal quarter, if the closing price of Cadence’s common stock exceeds $9.81 for 20 or more of the final 30 trading days in the preceding fiscal quarter;
Minimum closing price of common stock for specified days for conversion of notes								$ 27.50				$ 9.81
Minimum number of trading days limit for which closing price exceeds fixed price for conversion of notes								20 days				20 days
Number of final trading days range with in which closing price exceeds the fixed price for conversion of notes								30 days				30 days
Event 2								Specified corporate transactions occur				Specified corporate transactions occur;
Event 3								The trading price of the 2011 Notes and the 2013 Notes falls below 98% of the product of (i) the closing sale price of Cadence’s common stock and (ii) the conversion rate on that date				The trading price of the 2015 Notes falls below 98% of the product of (i) the closing sale price of Cadence's common stock and (ii) the conversion rate on that date
Percentage of product closing sale price of common stock and conversion rate on that date below which notes will be converted								98.00%				98.00%
Net Liability of the 2015 Notes		$ 420,982,000	$ 406,404,000								$ 290,600,000	$ 290,600,000
Conversion rate of Notes								47.2813 shares of Cadence common stock per $1,000 principal amount of the 2011 Notes and the 2013 Notes				132.5205 shares of Cadence common stock per $1,000 principal amount of the 2015 Notes
Debt instrument principal amount conversion rate for specified shares of common stock								1,000				1,000
Conversion rate for Convertible Senior Notes per thousand principal amount of Notes								47.2813				132.5205
Conversion rate of Convertible Senior Notes subject to certain conversion rate adjustments								$ 21.15			$ 7.55	$ 7.55
Condition 1								If a fundamental change, as defined in the indentures for the 2011 Notes and the 2013 Notes (which includes certain fundamental corporate changes relating to Cadence, such as certain mergers, recapitalizations, or sales of substantially all of its assets, or the delisting of its common stock), were to occur prior to maturity and Cadence’s stock price were greater than $18.00 per share at that time, the holders may be entitled to a "make-whole" premium in the form of an increase to the conversion rate.				If a fundamental change, as defined in the indenture for the 2015 Notes (which includes certain fundamental corporate changes relating to Cadence, such as certain mergers, recapitalizations, or sales of substantially all of its assets, or the delisting of its common stock), were to occur prior to maturity of the 2015 Notes and Cadence's stock price were greater than $6.16 per share at that time, then the holders of the 2015 Notes would be entitled to a "make-whole" premium in the form of an increase to the conversion rate.
Minimum closing price of common stock to make whole premium in the form of increase to conversion rate								$ 18.00				$ 6.16
Fair Value of 2015 Notes Embedded Conversion Derivative at the time of issuance										76,600,000
Estimated Fair Value of 2015 Notes Embedded Conversion Derivative at the balance sheet date											179,700,000	179,700,000
Cost of 2015 Notes Hedges										76,600,000
Estimated Fair Value of 2015 Notes hedges at the balance sheet date											179,700,000	179,700,000
Shares of Common Stock that can be purchased under warrants								23,600,000				46,400,000
Amount received in cash proceeds from the sale of the 2015 Warrants	37,450,000									37,500,000
Warrants to purchase shares of common stock price per share								$ 31.50				$ 10.78
Principal amount, issued						250,000,000				350,000,000					420,000,000				250,000,000
Remaining principal amount outstanding				150,000,000										200,000			144,500,000
Principal amount repurchased					100,000,000											5,500,000		100,000,000
Total estimated fair value											481,500,000	481,500,000		200,000
Principal amount of Convertible Senior Notes								294,461,000	294,461,000	350,000,000	350,000,000	350,000,000	350,000,000
Maximum purchase of Cadence's common stock shares, price per share								$ 31.50
Aggregate cost of 2011 Notes and 2013 Notes Hedges								119,800,000
Portion of sold of 2011 Notes and 2013 Notes hedges representing options to purchase Cadence's common stock									9,700,000
Proceeds received from sale of 2011 Notes and 2013 Notes Hedges									400,000
Estimated fair value of the remaining 2011 Notes and 2013 Notes Hedges								1,900,000
Amount received in cash proceeds from the sale of the 2011 Notes and 2013 Notes Warrants							39,400,000
Number of shares underlying warrants purchased with purchase of 2011 Notes and 2013 Notes									9,700,000
Cost for repurchase of portion of 2011 Notes and 2013 Notes Warrants									100,000
Notes Warrants expiration date description				various dates from February 2012 through April 2012													various dates from February 2014 through April 2014
Total estimated fair value (including equity component)								288,700,000
Proceeds from Convertible Debt	350,000,000									350,000,000
Impact on Income statement related to fair value adjustments of 2015 Notes Embedded Conversion Derivative and 2015 Notes Hedges											$ 0	$ 0