Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 29, 2018	Mar. 31, 2018
Available-for-sale securities
Amortized Cost	$ 3,353,743	$ 3,515,826
Gross Unrealized Gains	526	1,404
Gross Unrealized Losses	(50,541)	(40,444)
Estimated Fair Value	3,303,728	3,476,786
Money Market Funds [Member]
Available-for-sale securities
Amortized Cost	376,673	1,291,891
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Fair Value	376,673	1,291,891
Financial institution securities [Member]
Available-for-sale securities
Amortized Cost	628,965	434,901
Gross Unrealized Gains	15	0
Gross Unrealized Losses	0	0
Estimated Fair Value	628,980	434,901
Non-financial institution securities [Member]
Available-for-sale securities
Amortized Cost	574,630	326,219
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,294)	(1,376)
Estimated Fair Value	573,336	324,843
U.S. Government and Agency Securities [Member]
Available-for-sale securities
Amortized Cost	293,600	58,913
Gross Unrealized Gains	22	1
Gross Unrealized Losses	(337)	(272)
Estimated Fair Value	293,285	58,642
Foreign Government and Agency Securities [Member]
Available-for-sale securities
Amortized Cost	370,788	179,957
Gross Unrealized Gains	3	0
Gross Unrealized Losses	0	0
Estimated Fair Value	370,791	179,957
Mortgage-Backed Securities [Member]
Available-for-sale securities
Amortized Cost	775,806	866,048
Gross Unrealized Gains	476	660
Gross Unrealized Losses	(26,856)	(22,311)
Estimated Fair Value	749,426	844,397
Asset-backed Securities [Member]
Available-for-sale securities
Amortized Cost	86,664	92,751
Gross Unrealized Gains	9	16
Gross Unrealized Losses	(1,252)	(1,378)
Estimated Fair Value	85,421	91,389
Debt Mutual Fund [Member]
Available-for-sale securities
Amortized Cost	101,350	101,350
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(16,424)	(11,680)
Estimated Fair Value	84,926	89,670
Commercial Mortgage Backed Securities [Member]
Available-for-sale securities
Amortized Cost	137,767	156,296
Gross Unrealized Gains	1	1
Gross Unrealized Losses	(3,579)	(3,427)
Estimated Fair Value	134,189	152,870
Equity Securities [Member]
Available-for-sale securities
Amortized Cost	7,500	7,500
Gross Unrealized Gains	0	726
Gross Unrealized Losses	(799)	0
Estimated Fair Value	$ 6,701	$ 8,226

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562

+ Details

Name:	us-gaap_AvailableForSaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=xlnx_FinancialinstitutionsecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=xlnx_NonfinancialinstitutionsecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_ForeignGovernmentDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=xlnx_DebtMutualFundMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: