XML 69 R51.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Segment Information - Summary of Segment Information (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 29, 2018 | Sep. 29, 2018 | Jun. 30, 2018 | Mar. 31, 2018 | Dec. 30, 2017 | Sep. 30, 2017 | Jul. 01, 2017 | Apr. 01, 2017 | Dec. 29, 2018 | Dec. 30, 2017 | Dec. 31, 2016
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales | $ 559,087 | $ 645,958 | $ 662,773 | $ 640,060 | $ 523,524 | $ 550,363 | $ 614,266 | $ 577,920 | $ 2,507,878 | $ 2,266,073 | [1] | $ 2,055,622 | [1]
Cost of goods sold |  |  |  |  |  |  |  |  | 2,150,400 | 1,940,617 | [1] | 1,723,499 | [1]
Depreciation and amortization |  |  |  |  |  |  |  |  | 39,555 | 33,944 | [1] | 35,133 | [1]
Selling, general, and administrative expense |  |  |  |  |  |  |  |  | 148,888 | 140,730 | [1] | 135,811 | [1]
Gain on sale of assets, net |  |  |  |  |  |  |  |  | (253) | (1,491) | [1],[2] | 0 | [1],[2]
(Gain) loss on sale of assets |  |  |  |  |  |  |  |  | 0 | (1,491) |  | 0 |
Insurance recovery |  |  |  |  |  |  |  |  | (3,681) | 0 | [1] | 0 | [1]
Impairment charges |  |  |  |  | 1,100 |  |  |  | 0 | 1,466 | [1],[2] | 6,778 | [1],[2]
Operating income |  |  |  |  |  |  |  |  | 172,969 | 150,807 | [1] | 154,401 | [1]
Interest expense |  |  |  |  |  |  |  |  | (25,199) | (19,502) | [1] | (7,387) | [1]
Environmental expense |  |  |  |  |  |  |  |  | (1,320) | (7,284) | [1] | (1,279) | [1]
Other income, net |  |  |  |  |  |  |  |  | 3,967 | 2,951 | [1] | 295 | [1]
Income before income taxes |  |  |  |  |  |  |  |  | 150,417 | 126,972 | [1] | 146,030 | [1]
Expenditures for long-lived assets |  |  |  |  |  |  |  |  | 124,936 | 48,155 |  | 61,688 |
Impairment charges |  |  |  |  | 1,100 |  |  |  | 0 | 1,466 | [1],[2] | 6,778 | [1],[2]
Segment assets | 1,369,549 |  |  |  | 1,320,173 |  |  |  | 1,369,549 | 1,320,173 |  | 1,447,476 |
Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 2,525,763 | 2,298,529 |  | 2,070,407 |
Intersegment Eliminations [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | (17,885) | (32,456) |  | (14,785) |
Cost of goods sold |  |  |  |  |  |  |  |  | (18,152) | (34,368) |  | (16,282) |
Depreciation and amortization |  |  |  |  |  |  |  |  | 3,114 | 2,138 |  | 2,113 |
Selling, general, and administrative expense |  |  |  |  |  |  |  |  | 43,597 | 43,252 |  | 45,029 |
Gain on sale of assets, net |  |  |  |  |  |  |  |  | 3,141 | 0 |  |  |
Insurance recovery |  |  |  |  |  |  |  |  | 0 |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 0 |  | 0 |
Operating income |  |  |  |  |  |  |  |  | (49,585) | (43,478) |  | (45,645) |
Impairment charges |  |  |  |  |  |  |  |  |  | 0 |  | 0 |
Corporate Segment [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Expenditures for long-lived assets |  |  |  |  |  |  |  |  | 37 | 22,518 |  | 55 |
Segment assets | 130,670 |  |  |  | 232,609 |  |  |  | 130,670 | 232,609 |  | 393,367 |
Piping Systems [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 1,645,633 | 1,564,950 |  | 1,429,589 |
Cost of goods sold |  |  |  |  |  |  |  |  | 1,426,729 | 1,369,161 |  | 1,228,949 |
Depreciation and amortization |  |  |  |  |  |  |  |  | 23,304 | 21,777 |  | 22,421 |
Selling, general, and administrative expense |  |  |  |  |  |  |  |  | 74,864 | 74,441 |  | 67,178 |
Gain on sale of assets, net |  |  |  |  |  |  |  |  | (2,093) | (1,491) |  |  |
(Gain) loss on sale of assets |  |  |  |  |  |  |  |  |  | (1,500) |  |  |
Insurance recovery |  |  |  |  |  |  |  |  | 0 |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 1,466 |  | 6,115 |
Operating income |  |  |  |  |  |  |  |  | 122,829 | 99,596 |  | 104,926 |
Expenditures for long-lived assets |  |  |  |  |  |  |  |  | 31,362 | 18,124 |  | 56,286 |
Impairment charges |  |  |  |  |  |  |  |  |  | 1,466 |  | 6,115 |
Segment assets | 818,303 |  |  |  | 801,468 |  |  |  | 818,303 | 801,468 |  | 826,663 |
Industrial Metals [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 651,061 | 602,131 |  | 521,060 |
Cost of goods sold |  |  |  |  |  |  |  |  | 559,367 | 506,973 |  | 420,905 |
Depreciation and amortization |  |  |  |  |  |  |  |  | 7,568 | 7,516 |  | 8,162 |
Selling, general, and administrative expense |  |  |  |  |  |  |  |  | 13,501 | 13,278 |  | 13,943 |
Gain on sale of assets, net |  |  |  |  |  |  |  |  | (1,301) | 0 |  |  |
Insurance recovery |  |  |  |  |  |  |  |  | (3,681) |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 0 |  | 663 |
Operating income |  |  |  |  |  |  |  |  | 75,607 | 74,364 |  | 77,387 |
Expenditures for long-lived assets |  |  |  |  |  |  |  |  | 8,066 | 5,322 |  | 3,302 |
Impairment charges |  |  |  |  |  |  |  |  |  | 0 |  | 663 |
Segment assets | 173,725 |  |  |  | 212,638 |  |  |  | 173,725 | 212,638 |  | 160,478 |
Climate [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 229,069 | 131,448 |  | 119,758 |
Cost of goods sold |  |  |  |  |  |  |  |  | 182,456 | 98,851 |  | 89,927 |
Depreciation and amortization |  |  |  |  |  |  |  |  | 5,569 | 2,513 |  | 2,437 |
Selling, general, and administrative expense |  |  |  |  |  |  |  |  | 16,926 | 9,759 |  | 9,661 |
Gain on sale of assets, net |  |  |  |  |  |  |  |  | 0 | 0 |  |  |
Insurance recovery |  |  |  |  |  |  |  |  | 0 |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 0 |  | 0 |
Operating income |  |  |  |  |  |  |  |  | 24,118 | 20,325 |  | 17,733 |
Expenditures for long-lived assets |  |  |  |  |  |  |  |  | 85,471 | 2,191 |  | 2,045 |
Impairment charges |  |  |  |  |  |  |  |  |  | 0 |  | 0 |
Segment assets | $ 246,851 |  |  |  | $ 73,458 |  |  |  | 246,851 | 73,458 |  | 66,968 |
Tube and fittings [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 1,352,875 | 1,238,258 |  | 1,045,031 |
Tube and fittings [Member] | Piping Systems [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 1,352,875 | 1,238,258 |  | 1,045,031 |
Tube and fittings [Member] | Industrial Metals [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 0 | 0 |  | 0 |
Tube and fittings [Member] | Climate [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 0 | 0 |  | 0 |
Brass rod and forgings [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 501,472 | 461,603 |  | 369,363 |
Brass rod and forgings [Member] | Piping Systems [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 0 | 0 |  | 0 |
Brass rod and forgings [Member] | Industrial Metals [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 501,472 | 461,603 |  | 369,363 |
Brass rod and forgings [Member] | Climate [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 0 | 0 |  | 0 |
OEM components, tube and assemblies [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 222,272 | 277,538 |  | 334,353 |
OEM components, tube and assemblies [Member] | Piping Systems [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 29,578 | 94,383 |  | 145,017 |
OEM components, tube and assemblies [Member] | Industrial Metals [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 53,581 | 51,707 |  | 69,578 |
OEM components, tube and assemblies [Member] | Climate [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 139,113 | 131,448 |  | 119,758 |
Valves and plumbing specialties [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 263,180 | 232,309 |  | 239,541 |
Valves and plumbing specialties [Member] | Piping Systems [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 263,180 | 232,309 |  | 239,541 |
Valves and plumbing specialties [Member] | Industrial Metals [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 0 | 0 |  | 0 |
Valves and plumbing specialties [Member] | Climate [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 0 | 0 |  | 0 |
Other products [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 185,964 | 88,821 |  | 82,119 |
Other products [Member] | Piping Systems [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 0 | 0 |  | 0 |
Other products [Member] | Industrial Metals [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | 96,008 | 88,821 |  | 82,119 |
Other products [Member] | Climate [Member] | Operating Segments [Member] |  |  |  |  |  |  |  |  |  |  |  |  |
Segment Reporting Information, Income (Loss) before Income Taxes [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |
Net sales |  |  |  |  |  |  |  |  | $ 89,956 | $ 0 |  | $ 0 |
[1] | The Consolidated Statements of Income for prior periods have been adjusted to reflect the adoption of ASU 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The components of net periodic benefit cost (income) other than the service cost component are included in other income, net in the Consolidated Statements of Income. Refer to Note 1 for further discussion.
[2] | The Consolidated Statements of Cash Flows for prior periods have been adjusted to reflect the adoption of ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The Consolidated Statements of Cash Flows reflect the changes during the periods in the total of cash, cash equivalents, and restricted cash. Therefore, restricted cash activity is included with cash when reconciling the beginning-of-period and end-of-period total amounts shown. Refer to Note 1 for further discussion.

X
- Definition Environmental Remediation Expense, Non-Operating Properties + References No definition available. + Details
Name: | mli_EnvironmentalRemediationExpenseNonOperatingProperties
Namespace Prefix: | mli_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228 + Details
Name: | us-gaap_AssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(11)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(12)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 + Details
Name: | us-gaap_Assets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(a),(d)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_CostOfGoodsAndServicesSold
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
Name: | us-gaap_DepreciationDepletionAndAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of gain (loss) on sale or disposal of assets, including but not limited to property plant and equipment, intangible assets and equity in securities of subsidiaries or equity method investee. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
Name: | us-gaap_GainLossOnDispositionOfAssets1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of gain (loss) from sale and disposal of integrated set of activities and assets capable of being conducted and managed for purpose of providing return in form of dividend, lower cost, or other economic benefit to investor, owner, member and participant. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1B -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109239629&loc=SL4582445-111684 + Details
Name: | us-gaap_GainLossOnSaleOfBusiness
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(1)(i)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of the cost of borrowed funds accounted for as interest expense. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (210.5-03(11)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.9) -URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260 + Details
Name: | us-gaap_InterestExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The net result for the period of deducting operating expenses from operating revenues. + References No definition available. + Details
Name: | us-gaap_OperatingIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of income (expense) related to nonoperating activities, classified as other. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.9) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_OtherNonoperatingIncomeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentAdditions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045 + Details
Name: | us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_SegmentReportingInformationIncomeLossBeforeIncomeTaxesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Direct selling expenses (for example, credit, warranty, and advertising) are expenses that can be directly linked to the sale of specific products. Indirect selling expenses are expenses that cannot be directly linked to the sale of specific products, for example telephone expenses, Internet, and postal charges. General and administrative expenses include salaries of non-sales personnel, rent, utilities, communication, etc. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=68048583&loc=d3e3636-108311 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.4) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 + Details
Name: | us-gaap_SellingGeneralAndAdministrativeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 5.P.3) -URI http://asc.fasb.org/extlink&oid=115931487&loc=d3e140864-122747 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 5.P.4(b)) -URI http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
Name: | us-gaap_SeveranceCosts1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidationItemsAxis=us-gaap_CorporateNonSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mli_PipingSystemsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mli_IndustrialMetalsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mli_ClimateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=mli_TubeAndFittingsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=mli_BrassRodAndForgingsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=mli_OemComponentsTubeAndAssembliesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=mli_ValvesAndPlumbingSpecialtiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ProductOrServiceAxis=mli_OtherProductsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |