Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

+ Details

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

- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267

+ Details

Name:	us-gaap_GoodwillAcquiredDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Definition

Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfReportingUnits
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_ReportingUnitAxis=mchp_SemiconductorProductsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ReportingUnitAxis=mchp_TechnologyLicensingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=mchp_MicrosemiCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Intangible Assets and Goodwill - Goodwill by Reporting Segment (Details) $ in Millions	12 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2020 reporting_unit	Mar. 31, 2020 unit	Mar. 31, 2019 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 6,663.9
Goodwill, ending balance	6,664.8			$ 6,663.9
Number of reporting units		2	2
Semiconductor Products Reporting Unit
Goodwill [Roll Forward]
Goodwill, beginning balance	6,644.7			2,279.8
Additions	0.9
Goodwill, ending balance	6,645.6			6,644.7
Technology Licensing Reporting Unit
Goodwill [Roll Forward]
Goodwill, beginning balance	19.2			19.2
Additions	0.0
Goodwill, ending balance	$ 19.2			19.2
Microsemi Corporation \| Semiconductor Products Reporting Unit
Goodwill [Roll Forward]
Additions				4,364.9
Microsemi Corporation \| Technology Licensing Reporting Unit
Goodwill [Roll Forward]
Additions				$ 0.0