GOODWILL AND INTANGIBLE ASSETS - Schedule of Intangible Assets (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
Oct. 28, 2017	Apr. 29, 2017
Finite-lived Intangible Assets [Roll Forward]
Gross	$ 93.8	$ 42.2
Accumulated Amortization	37.2	35.6
Net	56.6	6.6
Customer Relationships and Agreements
Finite-lived Intangible Assets [Roll Forward]
Gross	56.5	16.3
Accumulated Amortization	16.2	15.6
Net	$ 40.3	$ 0.7
Wtd. Avg. Remaining Amortization Periods (Years)	9 years 9 months 21 days	6 years 9 months 18 days
Trade Names, Patents and Technology Licenses
Finite-lived Intangible Assets [Roll Forward]
Gross	$ 37.3	$ 25.8
Accumulated Amortization	21.0	19.9
Net	$ 16.3	$ 5.9
Wtd. Avg. Remaining Amortization Periods (Years)	7 years 3 months 6 days	1 year 4 months 24 days
Covenants Not to Compete
Finite-lived Intangible Assets [Roll Forward]
Gross		$ 0.1
Accumulated Amortization		0.1
Net		$ 0.0
Wtd. Avg. Remaining Amortization Periods (Years)		4 months 24 days

Finite-Lived Intangible Assets, Weighted Average Remaining Amortization Period

No definition available.

Name:	mei_FiniteLivedIntangibleAssetsWeightedAverageRemainingAmortizationPeriod
Namespace Prefix:	mei_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

+ Details

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

- Definition

Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

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

- Definition

Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

+ Details

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

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

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=mei_TradeNamesPatentsAndTechnologyLicencesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_NoncompeteAgreementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: