Income Taxes (Details 6) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
		Sep. 30, 2015	Jan. 02, 2016	Jan. 03, 2015	Dec. 28, 2013
Unrecognized Tax Benefits
Unrecognized tax benefits at the beginning of the fiscal year			$ 97,224	$ 78,279	$ 92,378
Gross amount of the increases (decreases) in unrecognized tax benefits of tax positions taken during a prior year	[1]		(7,331)	8,301	6,196
Gross amount of the increases in unrecognized tax benefits as a result of tax positions taken during the current year			7,513	12,381	5,119
Amount of decreases in unrecognized tax benefits relating to settlements with taxing authorities, including the utilization of tax attributes		$ (1,200)	(9,571)	0	(15,171)
Reductions to unrecognized tax benefits resulting from the lapse of the applicable statute of limitations			(119)	(86)	(11,850)
Effect of foreign currency translation			104	(1,651)	1,607
Unrecognized tax benefits at the end of the fiscal year			87,820	97,224	78,279
Total amounts of unrecognized tax benefits that, if upon resolution of the uncertain tax positions would reduce Cadence's effective tax rate			48,335	57,127	49,458
Interest and penalties recognized in Income Statements
Interest			110	255	(12,470)
Penalties			(127)	(748)	$ (7,698)
Interest and penalties recognized in Balance Sheets
Interest			1,128	1,155
Penalties			$ 270	$ 446

[1] Includes unrecognized tax benefits of tax positions recorded in connection with acquisitions