Name:	mli_ScheduleOfChangesInProjectedBenefitObligationsAndFairValueOfPlanAssetsTableTextBlock
Namespace Prefix:	mli_
Data Type:	dtr-types1:textBlockItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

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

Tabular disclosure of the major categories of plan assets of pension plans and/or other employee benefit plans. This information may include, but is not limited to, the target allocation of plan assets, the fair value of each major category of plan assets, and the level within the fair value hierarchy in which the fair value measurements fall.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 715
-SubTopic 20
-Subparagraph (d)(5)
-Name Accounting Standards Codification
-Paragraph 1
-Section 50
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Name:	us-gaap_ScheduleOfAllocationOfPlanAssetsTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of the amounts that are recognized in the balance sheet (or statement of financial position) for pension plans and/or other employee benefit plans, showing separately the assets and current and noncurrent liabilities (if applicable) recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Name:	us-gaap_ScheduleOfAmountsRecognizedInBalanceSheetTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of the net gain (loss) and net prior service cost or credit recognized in other comprehensive income (loss) for the period for pension plans and/or other employee benefit plans, and reclassification adjustments of other comprehensive income (loss) for the period, as those amounts, including amortization of the net transition asset or obligation, are recognized as components of net periodic benefit cost.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Name:	us-gaap_ScheduleOfAmountsRecognizedInOtherComprehensiveIncomeLossTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of assumption used to determine benefit obligation and net periodic benefit cost of defined benefit plan. Includes, but is not limited to, discount rate, rate of compensation increase, expected long-term rate of return on plan assets and interest crediting rate.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (k)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Name:	us-gaap_ScheduleOfAssumptionsUsedTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of the effect of fair value measurements using significant unobservable inputs (Level 3) on changes in plan assets of pension plans and/or other employee benefit plans for the period.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)(iv)(02)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Name:	us-gaap_ScheduleOfEffectOfSignificantUnobservableInputsChangesInPlanAssetsTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of benefits expected to be paid by pension plans and/or other employee benefit plans in each of the next five fiscal years and in the aggregate for the five fiscal years thereafter.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 715
-SubTopic 20
-Subparagraph (f)
-Name Accounting Standards Codification
-Paragraph 1
-Section 50
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Name:	us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 715
-SubTopic 20
-Subparagraph (h)
-Name Accounting Standards Codification
-Paragraph 1
-Section 50
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Name:	us-gaap_ScheduleOfNetBenefitCostsTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Tabular disclosure of net funded status of pension plans and/or other employee benefit plans.