Income Taxes (Details 7) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Jan. 01, 2011	Jan. 02, 2010
Unrecognized Tax Benefits
Unrecognized tax benefits at the beginning of the fiscal year	$ 131,545	$ 324,837	$ 322,742
Gross amount of the increases (decreases) in unrecognized tax benefits of tax positions taken during a prior year	(3,791)	(130,313)	(1,638)
Gross amount of the increases in unrecognized tax benefits as a result of tax positions taken during the current year	1,588	12,052	4,838
Amount of decreases in unrecognized tax benefits relating to settlements with taxing authorities, including the utilization of tax attributes	(30,115)	(74,890)	(1,061)
Reductions to unrecognized tax benefits resulting from the lapse of the applicable statute of limitations	(421)	(109)	(226)
Effect of foreign currency translation	6	(32)	182
Unrecognized tax benefits at the end of the fiscal year	98,812	131,545	324,837
Total amounts of unrecognized tax benefits that, if upon resolution of the uncertain tax positions would reduce Cadence's effective tax rate	75,057	83,676	257,589
Interest and penalties recognized in Statements of Operations
Interest	2,173	(46,268)	17,540
Penalties	(1,495)	4,471	1,043
Interest and penalties recognized in Balance Sheets
Interest	35,368	33,749
Penalties	$ 11,574	$ 15,260

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