Income Taxes (Details 2) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Mar. 31, 2018	[1],[2]	Dec. 30, 2017	[2]	Sep. 30, 2017	[2]	Jul. 01, 2017	[2]	Apr. 01, 2017	[3]	Dec. 31, 2016	[3]	Oct. 01, 2016	[3]	Jul. 02, 2016	[3]	Mar. 31, 2018	Apr. 01, 2017	Apr. 02, 2016
Income Tax Disclosure [Abstract]
Income before provision for taxes	$ 185,984		$ 195,169		$ 187,000		$ 182,259		$ 171,220		$ 162,580		$ 175,662		$ 181,618		$ 750,411	$ 691,080	$ 636,825
Federal statutory tax rate																	31.50%	35.00%	35.00%
Computed expected tax																	$ 236,668	$ 241,878	$ 222,889
State taxes, net of federal benefit																	10,338	1,741	3,177
Foreign earnings at lower tax rates																	(199,960)	(119,616)	(112,942)
Tax credits																	(19,708)	(34,146)	(25,211)
Transition tax																	208,523	0	0
Deferred tax remeasurement																	25,148	0	0
Excess benefits from stock-based compensation																	21,520	15,396	0
Other																	(1,459)	(5,893)	(1,955)
Total																	$ 238,030	$ 68,568	$ 85,958

[1] Income before income taxes for the fourth quarter of fiscal 2018 included executive transition costs of $33.4 million.

[2] Xilinx uses a 52- to 53-week fiscal year ending on the Saturday nearest March 31. Fiscal 2018 was a 52-week year and each quarter was a 13-week quarter.

[3] Xilinx uses a 52- to 53-week fiscal year ending on the Saturday nearest March 31. Fiscal 2017 was a 53-week year and each quarter was a 13-week quarter except the third quarter, which was a 14-week quarter.