The effective portion of gain reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

Name:	mli_DerivativeInstrumentsGainReclassifiedFromAccumulatedOciIntoIncomeEffectivePortionNoncontrollingInterest
Namespace Prefix:	mli
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of copper (in pounds) for which futures sales contracts have been written.

+ Details

Name:	mli_OpenCopperFuturesSalesContractsPounds
Namespace Prefix:	mli
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 45

-Subparagraph b(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 30

-Section 50

-Paragraph 1

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6887037&loc=d3e80748-113994

+ Details

Name:	us-gaap_CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount recognized in earnings related to the change in fair value during the period of derivative or nonderivative instruments designated as fair value hedging instruments.

+ References

+ Details

Name:	us-gaap_ChangeInUnrealizedGainLossOnFairValueHedgingInstruments
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount recognized in earnings related to the change in fair value during the period of the hedged item in a fair value hedge.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 45

-Subparagraph a(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 25

-Section 50

-Paragraph 1

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986

+ Details

Name:	us-gaap_ChangeInUnrealizedGainLossOnHedgedItemInFairValueHedge
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Fair value as of the balance sheet date of the gross assets less the gross liabilities of a derivative asset or group of derivative assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13495-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 45

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611

+ Details

Name:	us-gaap_DerivativeAssetFairValueNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6935481&loc=SL5624171-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 205G

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44C

-Subparagraph b

-Clause 2

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value as of the balance sheet date of the gross assets less the gross liabilities of a derivative liability or group of derivative liabilities.

+ References

+ Details

Name:	us-gaap_DerivativeLiabilityFairValueNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Aggregate notional amount of all derivatives. The notional amount relates to a number of currency units, shares, bushels, pounds, or other units specified in a derivative instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

+ Details

Name:	us-gaap_NotionalAmountOfDerivatives
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. This element is for unclassified presentations; for classified presentations there is a separate and distinct element.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 1

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-BRD

-Chapter 4

-Paragraph 80

-Subparagraph Exhibit 4-8, 3

-IssueDate 2006-05-01

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.1)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Derivative Instruments and Hedging Activities Part 2 (Details) (USD $)	9 Months Ended	12 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended
	Sep. 25, 2010	Oct. 01, 2012	Oct. 01, 2011	Oct. 01, 2011 Commodity contracts [Member]	Sep. 25, 2010 Commodity contracts [Member]	Oct. 01, 2011 Commodity contracts [Member]	Sep. 25, 2010 Commodity contracts [Member]	Oct. 01, 2011 Commodity contracts [Member] Fair Value Hedging [Member] Level 1 [Member] Cost of goods sold [Member]	Oct. 01, 2011 Commodity contracts [Member] Fair Value Hedging [Member] Level 1 [Member] Cost of goods sold [Member]	Oct. 01, 2011 Commodity contracts [Member] Fair Value Hedging [Member] Level 1 [Member] Inventory [Member]	Oct. 01, 2011 Commodity contracts [Member] Fair Value Hedging [Member] Level 1 [Member] Inventory [Member]	Oct. 01, 2011 Commodity contracts [Member] Cost of goods sold [Member]	Sep. 25, 2010 Commodity contracts [Member] Cost of goods sold [Member]	Oct. 01, 2011 Commodity contracts [Member] Cost of goods sold [Member]	Sep. 25, 2010 Commodity contracts [Member] Cost of goods sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) to be reclassified within the next twelve months		$ (4,400,000)
Open futures contracts to purchase commodities on related fixed price sales orders			28,400,000
Fair value of futures contracts loss position			(4,500,000)
Fair value of futures contracts gain position			1,800,000
Gain (loss) recognized in accumulated OCI (effective portion), net of tax				(2,386,000)	402,000	(1,593,000)	870,000
Gain (loss) recognized in accumulated OCI (effective portion), net of tax - noncontrolling portion	88,000											(790,000)	(69,000)	(1,816,000)	(727,000)
Open copper futures sales contracts			17,800,000
Gain on the hedged item in designated and qualifying fair value hedges								8,424,000	5,164,000
(Loss) on the derivatives in designated and qualifying fair value hedges										(7,915,000)	(4,987,000)
Recorded restricted cash related to open future contracts			$ 2,700,000