Income Taxes (Details 6) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
		Sep. 30, 2015	Dec. 31, 2016	Jan. 02, 2016	Jan. 03, 2015
Unrecognized Tax Benefits
Unrecognized tax benefits at the beginning of the fiscal year			$ 87,820	$ 97,224	$ 78,279
Gross amount of the decreases in unrecognized tax benefits of tax positions taken during a prior year	[1]		(155)	(7,331)
Gross amount of the increases in unrecognized tax benefits as a result of tax positions taken during the current year	[1]				8,301
Gross amount of the increases in unrecognized tax benefits as a result of tax positions taken during the current year			11,342	7,513	12,381
Amount of decreases in unrecognized tax benefits relating to settlements with taxing authorities, including the utilization of tax attributes		$ (1,200)	0	(9,571)	0
Reductions to unrecognized tax benefits resulting from the lapse of the applicable statute of limitations			(149)	(119)	(86)
Decrease resulting from foreign currency translation			(318)		(1,651)
Increase resulting from foreign currency translation				104
Unrecognized tax benefits at the end of the fiscal year			98,540	87,820	97,224
Total amounts of unrecognized tax benefits that, if upon resolution of the uncertain tax positions would reduce Cadence's effective tax rate			56,248	48,335	57,127
Interest and penalties recognized in Income Statements
Interest			1,166	110	255
Penalties			3	(127)	$ (748)
Interest and penalties recognized in Balance Sheets
Interest			1,332	1,128
Penalties			$ 265	$ 270

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