Mueller Industries (MLI) 10-Q 21 Apr 21 2021 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 27, 2021	Apr. 16, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 27, 2021
Document Transition Report	false
Entity File Number	1-6770
Entity Registrant Name	MUELLER INDUSTRIES INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	25-0790410
Entity Address, Address Line One	150 Schilling Boulevard
Entity Address, Address Line Two	Suite 100
Entity Address, City or Town	Collierville
Entity Address, State or Province	TN
Entity Address, Postal Zip Code	38017
City Area Code	901
Local Phone Number	753-3200
Title of 12(b) Security	Common Stock
Trading Symbol	MLI
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		57,127,506
Entity Central Index Key	0000089439
Current Fiscal Year End Date	--12-25
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Income Statement [Abstract]
Net sales	$ 818,148	$ 602,919
Cost of goods sold	668,418	508,715
Depreciation and amortization	11,755	11,039
Selling, general, and administrative expense	45,435	42,752
Asset impairments	0	3,035
Litigation settlement, net	0	(21,933)
Operating income	92,540	59,311
Interest expense	(4,469)	(5,379)
Other income, net	577	278
Income before income taxes	88,648	54,210
Income tax expense	(21,761)	(14,144)
Loss from unconsolidated affiliates, net of foreign tax	(1,649)	(6,115)
Consolidated net income	65,238	33,951
Net income attributable to noncontrolling interests	(2,131)	(1,536)
Net income attributable to Mueller Industries, Inc.	$ 63,107	$ 32,415
Weighted average shares for basic earnings per share (in shares)	55,916	55,875
Effect of dilutive stock-based awards (in shares)	756	583
Adjusted weighted average shares for diluted earnings per share (in shares)	56,672	56,458
Basic earnings per share (in dollars per share)	$ 1.13	$ 0.58
Diluted earnings per share (in dollars per share)	1.11	0.57
Dividends per share (in dollars per share)	$ 0.13	$ 0.10

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Statement of Comprehensive Income [Abstract]
Consolidated net income	$ 65,238	$ 33,951
Other comprehensive income (loss), net of tax:
Foreign currency translation	4,387	(21,255)
Net change with respect to derivative instruments and hedging activities, net of tax of $(147) and $960	493	(3,357)
Net change in pension and postretirement obligation adjustments, net of tax of $56 and $(243)	(91)	739
Attributable to unconsolidated affiliates, net of tax of $(577) and $(548)	1,987	1,887
Total other comprehensive income (loss), net	6,776	(21,986)
Consolidated comprehensive income	72,014	11,965
Comprehensive income attributable to noncontrolling interests	(2,552)	(945)
Comprehensive income attributable to Mueller Industries, Inc.	$ 69,462	$ 11,020

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Statement of Comprehensive Income [Abstract]
Net change with respect to derivative instruments and hedging activities, tax (expense) benefit	$ (147)	$ 960
Net actuarial loss on pension and postretirement obligations, tax benefit (expense)	56	(243)
Attributable to unconsolidated affiliates, tax benefit (expense)	$ (577)	$ (548)

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Current assets:
Cash and cash equivalents	$ 129,876	$ 119,075
Accounts receivable, less allowance for doubtful accounts of $3,168 in 2021 and $1,538 in 2020	447,492	357,532
Inventories	365,457	315,002
Other current assets	43,710	33,752
Total current assets	986,535	825,361
Property, plant, and equipment, net	384,853	376,572
Operating lease right-of-use assets	28,494	29,301
Goodwill, net	168,207	167,764
Intangible assets, net	77,784	77,207
Investments in unconsolidated affiliates	38,891	37,976
Other assets	13,565	14,387
Total assets	1,698,329	1,528,568
Current liabilities:
Current portion of debt	106,164	41,283
Accounts payable	177,174	147,741
Accrued wages and other employee costs	39,426	46,299
Current portion of operating lease liabilities	6,567	6,259
Other current liabilities	115,157	98,061
Total current liabilities	444,488	339,643
Long-term debt, less current portion	286,576	286,593
Pension liabilities	12,183	13,552
Postretirement benefits other than pensions	13,285	13,289
Environmental reserves	21,322	21,256
Deferred income taxes	17,127	16,842
Noncurrent operating lease liabilities	20,832	21,602
Other noncurrent liabilities	14,503	14,731
Total liabilities	830,316	727,508
Mueller Industries, Inc. stockholders' equity:
Preferred stock - $1.00 par value; shares authorized 5,000,000; none outstanding	0	0
Common stock - $.01 par value; shares authorized 100,000,000; issued 80,183,004; outstanding 57,122,617 in 2021 and 57,087,432 in 2020	802	802
Additional paid-in capital	282,713	280,051
Retained earnings	1,075,410	1,019,694
Accumulated other comprehensive loss	(48,528)	(54,883)
Treasury common stock, at cost	(469,251)	(468,919)
Total Mueller Industries, Inc. stockholders' equity	841,146	776,745
Noncontrolling interests	26,867	24,315
Total equity	868,013	801,060
Total liabilities and equity	$ 1,698,329	$ 1,528,568

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 3,168	$ 1,538
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	80,183,004	80,183,004
Common stock, shares outstanding (in shares)	57,122,617	57,087,432

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Cash flows from operating activities
Consolidated net income	$ 65,238	$ 33,951
Reconciliation of consolidated net income to net cash (used in) provided by operating activities:
Depreciation and amortization	11,775	11,119
Stock-based compensation expense	2,109	1,985
Provision for doubtful accounts receivable	1,631	1,100
Loss from unconsolidated affiliates	1,649	6,115
(Gain) loss on disposals of properties	(936)	32
Impairment charges	0	3,035
Deferred income tax expense	142	213
Changes in assets and liabilities, net of effects of businesses acquired:
Receivables	(89,972)	(46,291)
Inventories	(45,590)	17,450
Other assets	1,230	8,010
Current liabilities	33,941	(10,821)
Other liabilities	(3,703)	(1,643)
Other, net	(95)	3,796
Net cash (used in) provided by operating activities	(22,581)	28,051
Cash flows from investing activities
Capital expenditures	(9,227)	(17,094)
Acquisition of businesses, net of cash acquired	(14,029)	(15,407)
Proceeds from sales of assets	1,730	0
Net cash used in investing activities	(21,526)	(32,501)
Cash flows from financing activities
Repurchase of common stock	0	(5,574)
Issuance of debt	100,000	110,000
Repayments of debt	(35,288)	(20,572)
Issuance of debt by consolidated joint ventures, net	45	189
Net cash received to settle stock-based awards	221	464
Net cash provided by financing activities	64,978	84,507
Effect of exchange rate changes on cash	784	(6,135)
Increase in cash, cash equivalents, and restricted cash	21,655	73,922
Cash, cash equivalents, and restricted cash at the beginning of the period	127,376	98,042
Cash, cash equivalents, and restricted cash at the end of the period	$ 149,031	$ 171,964

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Balance at beginning of period at Dec. 28, 2019		$ 802	$ 278,609	$ 903,070	$ (68,770)	$ (470,243)	$ 18,668
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Acquisition (issuance) of shares under incentive stock option plans			(397)			860
Stock-based compensation expense			1,985
Net income attributable to Mueller Industries, Inc.	$ 32,415			32,415
Dividends paid or payable to stockholders of Mueller Industries, Inc.				(5,675)
Total other comprehensive income (loss) attributable to Mueller Industries, Inc.	(21,986)				(21,395)
Repurchase of common stock						(5,574)
Net income attributable to noncontrolling interests	(1,536)						1,536
Foreign currency translation	(21,255)						(591)
Balance at end of period at Mar. 28, 2020		802	280,197	929,810	(90,165)	(474,957)	19,613
Balance at beginning of period at Dec. 26, 2020	801,060	802	280,051	1,019,694	(54,883)	(468,919)	24,315
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Acquisition (issuance) of shares under incentive stock option plans			553			(306)
Stock-based compensation expense			2,109
Net income attributable to Mueller Industries, Inc.	63,107			63,107
Dividends paid or payable to stockholders of Mueller Industries, Inc.				(7,391)
Total other comprehensive income (loss) attributable to Mueller Industries, Inc.	6,776				6,355
Repurchase of common stock						(26)
Net income attributable to noncontrolling interests	(2,131)						2,131
Foreign currency translation	4,387						421
Balance at end of period at Mar. 27, 2021	$ 868,013	$ 802	$ 282,713	$ 1,075,410	$ (48,528)	$ (469,251)	$ 26,867

Recent Accounting Standards

Recent Accounting Standards	3 Months Ended
	Mar. 27, 2021
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Standards	Recent Accounting Standards Adopted In October 2020, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2020-10, Codification Improvements: An Amendment of the FASB Accounting Standards Codification . The ASU facilitates updates to the Accounting Standards Codification for technical corrections such as conforming amendments, clarifications to guidance, simplifications to wording or structure of guidance, and other minor improvements. The Company adopted the ASU during the first quarter of 2021 using a retrospective approach. The adoption of the ASU did not have a material impact on the Company’s Condensed Consolidated Financial Statements. In January 2020, the FASB issued ASU No. 2020-01, Investments - Equity Securities (Topic 321), Investments - Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815): Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 . The new guidance addresses accounting for the transition into and out of the equity method and measuring certain purchased options and forward contracts to acquire investments. The Company adopted the ASU during the first quarter of 2021 using a prospective approach. The adoption of the ASU did not have a material impact on the Company’s Condensed Consolidated Financial Statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes: Simplifying the Accounting for Income Taxes . The new guidance affects general principles within Topic 740, Income Taxes. The amendments of ASU 2019-12 are meant to simplify and reduce the cost of accounting for income taxes. The Company adopted the ASU during the first quarter of 2021 using a prospective approach. The adoption of the ASU did not have a material impact on the Company’s Condensed Consolidated Financial Statements. Issued In January 2021, the FASB issued ASU No. 2021-01, Reference Rate Reform (Topic 848): An Amendment of the FASB Accounting Standards Codification. The new guidance was issued in response to concerns about structural risks of interbank offered rates, and, particularly, the risk of cessation of the London Interbank Offered Rate (LIBOR). Regulators in numerous jurisdictions around the world have undertaken reference rate reform initiatives to identify alternative reference rates that are more observable or transaction based and less susceptible to manipulation. The ASU is effective in 2021 but can be applied through December 31, 2022. The updated guidance requires retrospective adoption, and early adoption is permitted. The Company does not expect the adoption of the ASU to have a material impact on its Condensed Consolidated Financial Statements.

Earnings per Common Share

Earnings per Common Share	3 Months Ended
	Mar. 27, 2021
Earnings Per Share [Abstract]
Earnings per Common Share	Earnings per Common ShareBasic per share amounts have been computed based on the average number of common shares outstanding.  Diluted per share amounts reflect the increase in average common shares outstanding that would result from the assumed exercise of outstanding stock options and vesting of restricted stock awards, computed using the treasury stock method.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 27, 2021
Business Combinations [Abstract]
Acquisitions	Acquisitions H&C Flex On December 20, 2020, the Company entered into an asset purchase agreement with Hart & Cooley LLC. The transaction closed on January 29, 2021, whereby the Company purchased the Hart & Cooley flexible duct business, which included inventory, manufacturing equipment, and related assets. The total purchase price was $14.0 million in cash paid at closing. The Company treated this as a business combination. The acquired business, H&C Flex, is a manufacturer and distributor of insulated HVAC flexible duct systems. It is reported within and complements the Company’s existing businesses in the Climate segment. The provisional fair value of tangible assets acquired totaled $12.9 million, consisting primarily of property, plant, and equipment of $8.4 million and inventory of $4.5 million. Of the remaining purchase price, $1.1 million was allocated to tax-deductible goodwill. The purchase price allocation is provisional as of March 27, 2021 and subject to change upon completion of the final valuation of the long-lived assets during the measurement period. Kessler Sales and Distribution, LLC On August 3, 2020, the Company entered into an asset purchase agreement with Wieland-Kessler LLC, whereby the Company purchased the Kessler distribution business, which included inventory, manufacturing equipment, and related assets. The total purchase price was $57.2 million in cash paid at closing. The Company treated this as a business combination. The acquired business, Kessler Sales and Distribution, LLC, is a distributor of residential and commercial plumbing products. It is reported within and complements the Company’s existing businesses in the Piping Systems segment. The provisional fair value of tangible assets acquired totaled $28.7 million, consisting primarily of inventory. Of the remaining purchase price, $28.5 million was allocated to tax-deductible goodwill and intangible assets. During the first quarter of 2021, there was a change in the valuation that resulted in a decrease in goodwill and an increase in intangible assets of $1.5 million. The purchase price allocation is provisional as of March 27, 2021 and subject to change upon completion of the final valuation of the long-lived assets during the measurement period. Shoals Tubular, Inc. On January 17, 2020, the Company entered into a stock purchase agreement pursuant to which the Company acquired all of the outstanding stock of Shoals Tubular, Inc. (STI) for approximately $15.3 million, net of working capital adjustments. The total purchase price consisted of $15.3 million in cash at closing. STI is a manufacturer of brazed manifolds, headers, and distributor assemblies used primarily by manufacturers of residential heating and air conditioning units. The acquired business is reported within and complements the Company’s existing businesses in the Climate segment. The fair value of the tangible assets acquired totaled $6.2 million, consisting primarily of property, plant, and equipment of $3.7 million, inventories of $1.8 million, and accounts receivable of $0.7 million. The fair value of the liabilities assumed totaled $0.2 million, consisting primarily of accounts payable. Of the remaining purchase price, $9.3 million was allocated to tax-deductible goodwill and intangible assets. The valuation of the business has been finalized. There were no material changes to the purchase price allocation from the amounts presented in the Company’s 2020 Annual Report on Form 10-K.

Segment Information

Segment Information	3 Months Ended
	Mar. 27, 2021
Segment Reporting [Abstract]
Segment Information	Segment InformationEach of the Company’s reportable segments is composed of certain operating segments that are aggregated primarily by the nature of products offered as follows: Piping Systems Piping Systems is composed of the following operating segments: Domestic Piping Systems Group, Great Lakes Copper, Heatlink Group, Die-Mold, European Operations, Trading Group, an d Jungwoo-Mueller (the Company’s South Korean joint venture). The Domestic Piping Systems Group manufactures and distributes copper tube, fittings, and line sets. These products are manufactured in the U.S., sold in the U.S., and exported to markets worldwide. Outside the U.S., Great Lakes Copper manufactures copper tube and line sets in Canada and sells the products primarily in the U.S. and Canada. Heatlink Group produces a complete line of products for PEX plumbing and radiant systems in Canada and sells these products in Canada and the U.S. Die-Mold manufactures PEX and other plumbing-related fittings and plastic injection tooling in Canada and sells these products in Canada and the U.S. European Operations manufactures copper tube in the U.K. which is sold primarily in Europe. The Trading Group manufactures pipe nipples and resells brass and plastic plumbing valves, malleable iron fittings, faucets, and plumbing specialty products in the U.S. and Mexico. Jungwoo-Mueller manufactures copper-based joining products that are sold worldwide. The Piping Systems segment’s products are sold primarily to plumbing, refrigeration, and air-conditioning wholesalers, hardware wholesalers and co-ops, building product retailers, and air-conditioning original equipment manufacturers (OEMs). Industrial Metals Industrial Metals is composed of the following operating segments: Brass Rod & Copper Bar Products, Impacts & Micro Gauge, and Brass Value-Added Products. These businesses manufacture brass rod, impact extrusions, and forgings, as well as a wide variety of end products including plumbing brass, automotive components, valves, fittings, and gas assemblies. These products are manufactured in the U.S. and sold primarily to OEMs in the U.S., many of which are in the industrial, transportation, construction, heating, ventilation, and air-conditioning, plumbing, refrigeration, and energy markets. Climate Climate is composed of the following operating segments: Refrigeration Products, Fabricated Tube Products, Westermeyer, Turbotec, Flex Duct , Linesets, Inc., and STI. These domestic businesses manufacture and fabricate valves, assemblies, high pressure components, coaxial heat exchangers, insulated HVAC flexible duct systems, line sets, brazed manifolds, headers, and distributor assemblies primarily for the heating, ventilation, air-conditioning, and refrigeration markets in the U.S. Summarized segment information is as follows: For the Quarter Ended March 27, 2021 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 547,748 $ 164,852 $ 111,026 $ (5,478) $ 818,148 Cost of goods sold 450,354 140,891 84,082 (6,909) 668,418 Depreciation and amortization 6,210 1,743 2,629 1,173 11,755 Selling, general, and administrative expense 24,086 3,371 6,980 10,998 45,435 Operating income 67,098 18,847 17,335 (10,740) 92,540 Interest expense (4,469) Other income, net 577 Income before income taxes $ 88,648 Segment information (continued): For the Quarter Ended March 28, 2020 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 385,013 $ 131,202 $ 93,272 $ (6,568) $ 602,919 Cost of goods sold 319,164 114,797 71,093 3,661 508,715 Depreciation and amortization 5,699 2,002 2,466 872 11,039 Selling, general, and administrative expense 20,439 3,221 6,699 12,393 42,752 Asset impairments 3,035 — — — 3,035 Litigation settlement, net — — — (21,933) (21,933) Operating income 36,676 11,182 13,014 (1,561) 59,311 Interest expense (5,379) Other income, net 278 Income before income taxes $ 54,210 The following tables represent a disaggregation of revenue from contracts with customers, along with the reportable segment for each category: For the Quarter Ended March 27, 2021 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 426,139 $ — $ — $ 426,139 Brass rod and forgings — 131,262 — 131,262 OEM components, tube & assemblies 8,555 11,033 38,067 57,655 Valves and plumbing specialties 113,054 — — 113,054 Other — 22,557 72,959 95,516 547,748 164,852 111,026 823,626 Intersegment sales (5,478) Net sales $ 818,148 Disaggregation of revenue from contracts with customers (continued): For the Quarter Ended March 28, 2020 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 302,129 $ — $ — $ 302,129 Brass rod and forgings — 99,670 — 99,670 OEM components, tube & assemblies 25,295 10,882 36,573 72,750 Valves and plumbing specialties 57,589 — — 57,589 Other — 20,650 56,699 77,349 385,013 131,202 93,272 609,487 Intersegment sales (6,568) Net sales $ 602,919

Cash, Cash Equivalents, and Res

Cash, Cash Equivalents, and Restricted Cash	3 Months Ended
	Mar. 27, 2021
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents, and Restricted Cash (In thousands) March 27, December 26, Cash & cash equivalents $ 129,876 $ 119,075 Restricted cash included within other current assets 19,052 8,198 Restricted cash included within other assets 103 103 Total cash, cash equivalents, and restricted cash $ 149,031 $ 127,376 Amounts included in restricted cash relate to required deposits in brokerage accounts that facilitate the Company’s hedging activities as well as imprest funds for the Company’s self-insured workers’ compensation program.

Inventories

Inventories	3 Months Ended
	Mar. 27, 2021
Inventory Disclosure [Abstract]
Inventories	Inventories (In thousands) March 27, December 26, Raw materials and supplies $ 119,196 $ 85,927 Work-in-process 52,803 49,361 Finished goods 201,748 186,785 Valuation reserves (8,290) (7,071) Inventories $ 365,457 $ 315,002

Financial Instruments

Financial Instruments	3 Months Ended
	Mar. 27, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	Financial Instruments Derivative Instruments and Hedging Activities The Company’s earnings and cash flows are subject to fluctuations due to changes in commodity prices, foreign currency exchange rates, and interest rates. The Company uses derivative instruments such as commodity futures contracts, foreign currency forward contracts, and interest rate swaps to manage these exposures. All derivatives are recognized in the Condensed Consolidated Balance Sheets at their fair value. On the date the derivative contract is entered into, it is either a) designated as a hedge of a forecasted transaction or the variability of cash flow to be paid (cash flow hedge) or b) not designated in a hedge accounting relationship, even though the derivative contract was executed to mitigate an economic exposure (economic hedge), as the Company does not enter into derivative contracts for trading purposes. Changes in the fair value of a derivative that is qualified, designated, and highly effective as a cash flow hedge are recorded in stockholders’ equity within AOCI, to the extent effective, until they are reclassified to earnings in the same period or periods during which the hedged transaction affects earnings. Changes in the fair value of undesignated derivatives executed as economic hedges are reported in current earnings. The Company documents all relationships between derivative instruments and hedged items, as well as the risk-management objective and strategy for undertaking various hedge transactions. This process includes linking all derivative instruments that are designated as fair value hedges to specific assets and liabilities in the Condensed Consolidated Balance Sheets and linking cash flow hedges to specific forecasted transactions or variability of cash flow. The Company also assesses, both at the hedge’s inception and on an ongoing basis, whether the designated derivative instruments that are used in hedging transactions are highly effective in offsetting changes in cash flows or fair values of hedged items. When a derivative instrument is determined not to be highly effective as a hedge or the underlying hedged transaction is no longer probable of occurring, hedge accounting is discontinued prospectively in accordance with the derecognition criteria for hedge accounting. Commodity Futures Contracts Copper and brass represent the largest component of the Company’s variable costs of production. The cost of these materials is subject to global market fluctuations caused by factors beyond the Company’s control. The Company occasionally enters into forward fixed-price arrangements with certain customers; the risk of these arrangements is generally managed with commodity futures contracts. These futures contracts have been designated as cash flow hedges. At March 27, 2021, the Company held open futures contracts to purchase approximately $21.2 million of copper over the next 14 months related to fixed price sales orders. The fair value of those futures contracts was a $1.9 million net gain position, which was determined by obtaining quoted market prices (level 1 within the fair value hierarchy). In the next 12 months, the Company will reclassify into earnings realized gains or losses relating to cash flow hedges. At March 27, 2021, this amount was approximately $1.3 million of deferred net gains, net of tax. The Company may also enter into futures contracts to protect the value of inventory against market fluctuations. At March 27, 2021, the Company held open futures contracts to sell approximately $70.8 million of copper over the next six months related to copper inventory. The fair value of those futures contracts was a $14.6 million net loss position, which was determined by obtaining quoted market prices (level 1 within the fair value hierarchy). The Company presents its derivative assets and liabilities in the Condensed Consolidated Balance Sheets on a net basis by counterparty. The following table summarizes the location and fair value of the derivative instruments and disaggregates the net derivative assets and liabilities into gross components on a contract-by-contract basis: Asset Derivatives Liability Derivatives Fair Value Fair Value (In thousands) Balance Sheet Location March 27, December 26, Balance Sheet Location March 27, December 26, Commodity contracts - gains Other current assets $ 1,965 $ 1,213 Other current liabilities $ — $ 68 Commodity contracts - losses Other current assets (55) (8) Other current liabilities (14,667) (5,863) Total derivatives (1) $ 1,910 $ 1,205 $ (14,667) $ (5,795) (1) Does not include the impact of cash collateral provided to counterparties. The following tables summarize the effects of derivative instruments on the Company’s Condensed Consolidated Statements of Income: For the Quarter Ended (In thousands) Location March 27, 2021 March 28, 2020 Undesignated derivatives: Loss on commodity contracts (nonqualifying) Cost of goods sold (8,530) (9,476) The following tables summarize amounts recognized in and reclassified from AOCI during the period: For the Quarter Ended March 27, 2021 (In thousands) Gain (Loss) Recognized in AOCI (Effective Portion), Net of Tax Classification Gains (Losses) (Gain) Loss Reclassified from AOCI (Effective Portion), Net of Tax Cash flow hedges: Commodity contracts $ 1,491 Cost of goods sold $ (996) Other (3) Other 1 Total $ 1,488 Total $ (995) For the Quarter Ended March 28, 2020 (In thousands) Loss Recognized in AOCI (Effective Portion), Net of Tax Classification Gains (Losses) Loss Reclassified from AOCI (Effective Portion), Net of Tax Cash flow hedges: Commodity contracts $ (3,706) Cost of goods sold $ 378 Other (29) Other — Total $ (3,735) Total $ 378 The Company primarily enters into International Swaps and Derivatives Association master netting agreements with major financial institutions that permit the net settlement of amounts owed under their respective derivative contracts. Under these master netting agreements, net settlement generally permits the Company or the counterparty to determine the net amount payable for contracts due on the same date and in the same currency for similar types of derivative transactions. The master netting agreements generally also provide for net settlement of all outstanding contracts with a counterparty in the case of an event of default or a termination event. The Company does not offset fair value amounts for derivative instruments and fair value amounts recognized for the right to reclaim cash collateral. At March 27, 2021 and December 26, 2020, the Company had recorded restricted cash in other current assets of $18.6 million and $7.6 million, respectively, as collateral related to open derivative contracts under the master netting arrangements. Long-Term Debt

Investments in Unconsolidated A

Investments in Unconsolidated Affiliates	3 Months Ended
	Mar. 27, 2021
Equity Method Investments and Joint Ventures [Abstract]
Investments in Unconsolidated Affiliates	Investments in Unconsolidated Affiliates Tecumseh The Company owns a 50 percent interest in an unconsolidated affiliate that acquired Tecumseh Products Company LLC (Tecumseh). The Company also owns a 50 percent interest in a second unconsolidated affiliate that provides financing to Tecumseh. These investments are recorded using the equity method of accounting, as the Company can exercise significant influence but does not own a majority equity interest or otherwise control the respective entities. Under the equity method of accounting, these investments are stated at initial cost and are adjusted for subsequent additional investments and the Company’s proportionate share of earnings or losses and distributions. The Company records its proportionate share of the investees’ net income or loss, net of foreign taxes, one quarter in arrears as income (loss) from unconsolidated affiliates, net of foreign tax, in the Condensed Consolidated Statements of Income and its proportionate share of the investees’ other comprehensive income (loss), net of income taxes, in the Condensed Consolidated Statements of Comprehensive Income and the Condensed Consolidated Statements of Changes in Equity. The U.S. tax effect of the Company’s proportionate share of Tecumseh’s income or loss is recorded in income tax expense in the Condensed Consolidated Statements of Income. In general, the equity investment in unconsolidated affiliates is equal to the current equity investment plus the investees’ net accumulated losses. The following tables present summarized financial information derived from the Company’s equity method investees’ combined consolidated financial statements, which are prepared in accordance with U.S. GAAP. (In thousands) March 27, December 26, Current assets $ 171,907 $ 167,451 Noncurrent assets 82,198 78,241 Current liabilities 127,317 120,202 Noncurrent liabilities 49,463 50,020 For the Quarter Ended (In thousands) March 27, 2021 March 28, 2020 Net sales $ 97,329 $ 106,998 Gross profit 9,699 13,486 Net loss (3,299) (12,685) The Company’s loss from unconsolidated affiliates, net of foreign tax, for the quarters ended March 27, 2021 and March 28, 2020 included net losses of $1.6 million and $6.3 million, respectively, for Tecumseh. Mueller Middle East On December 30, 2015, the Company entered into a joint venture agreement with Cayan Ventures and Bahrain Mumtalakat Holding Company to build a copper tube mill in Bahrain. The business operates and brands its products under the Mueller Industries family of brands. The Company has invested approximately $5.0 million of cash to date and is the technical and marketing lead with a 40 percent ownership in the joint venture.

Benefit Plans

Benefit Plans	3 Months Ended
	Mar. 27, 2021
Retirement Benefits [Abstract]
Benefit Plans	Benefit Plans The Company sponsors several qualified and nonqualified pension plans and other postretirement benefit plans for certain of its employees. The components of net periodic benefit cost (income) are as follows: For the Quarter Ended (In thousands) March 27, 2021 March 28, 2020 Pension benefits: Interest cost $ 313 $ 858 Expected return on plan assets (904) (1,495) Amortization of net loss 378 460 Net periodic benefit income $ (213) $ (177) Other benefits: Service cost $ 65 $ 61 Interest cost 87 109 Amortization of prior service credit (118) (226) Amortization of net gain (31) (53) Net periodic benefit cost (income) $ 3 $ (109) The components of net periodic benefit cost (income) other than the service cost component are included in other income, net in the Condensed Consolidated Statements of Income.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 27, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company is involved in certain litigation as a result of claims that arose in the ordinary course of business, which management believes will not have a material adverse effect on the Company’s financial position, results of operations, or cash flows. The Company may also realize the benefit of certain legal claims and litigation in the future; these gain contingencies are not recognized in the Condensed Consolidated Financial Statements. Environmental Non-operating Properties Southeast Kansas Sites The Kansas Department of Health and Environment (KDHE) has contacted the Company regarding environmental contamination at three former smelter sites in Kansas (Altoona, East La Harpe, and Lanyon). The Company is not a successor to the companies that operated these smelter sites, but is exploring possible settlement with KDHE and other potentially responsible parties (PRP) in order to avoid litigation. Altoona. Another PRP conducted a site investigation of the Altoona site under a consent decree with KDHE and submitted a removal site evaluation report recommending a remedy. The remedial design plan, which covers both on-site and certain off-site cleanup costs, was approved by the KDHE in 2016. Construction of the remedy was completed in 2018. East La Harpe. At the East La Harpe site, the Company and two other PRPs conducted a site study evaluation under KDHE supervision and prepared a site cleanup plan approved by KDHE. In 2016, the corporate parent (Peabody Energy) of a third party that the Company understands may owe indemnification obligations to one of the other PRPs (Blue Tee) in connection with the East La Harpe site filed for protection under Chapter 11 of the U.S. Bankruptcy Code. KDHE has extended the deadline for the PRPs to develop a repository design plan to allow for wetlands permitting to take place. In December 2018, KDHE provided a draft agreement which contemplates the use of funds KDHE obtained from two other parties (Peabody Energy and Blue Tee) to fund part of the remediation, and removes Blue Tee from the PRPs’ agreement with KDHE. The Company is currently negotiating the terms of that draft agreement. Lanyon. With respect to the Lanyon Site, in 2016, the Company received a general notice letter from the United States Environmental Protection Agency (EPA) asserting that the Company is a PRP, which the Company has denied. EPA issued an interim record of decision in 2017 and has been remediating properties at the site. The Company’s reserve for its proportionate share of the remediation costs associated with these three Southeast Kansas sites is $5.6 million. Shasta Area Mine Sites Mining Remedial Recovery Company (MRRC), a wholly owned subsidiary, owns certain inactive mines in Shasta County, California. MRRC has continued a program, begun in the late 1980s, of implementing various remedial measures, including sealing mine portals with concrete plugs in portals that were discharging water. The sealing program achieved significant reductions in the metal load in discharges from these adits; however, additional reductions are required pursuant to an order issued by the California Regional Water Quality Control Board (QCB). In response to a 1996 QCB Order, MRRC completed a feasibility study in 1997 describing measures designed to mitigate the effects of acid rock drainage. In December 1998, the QCB modified the 1996 order extending MRRC’s time to comply with water quality standards. In September 2002, the QCB adopted a new order requiring MRRC to adopt Best Management Practices (BMP) to control discharges of acid mine drainage, and again extended the time to comply with water quality standards until September 2007. During that time, implementation of BMP further reduced impacts of acid rock drainage; however, full compliance has not been achieved. The QCB is presently renewing MRRC’s discharge permit and will concurrently issue a new order. It is expected that the new 10-year permit will include an order requiring continued implementation of BMP through 2030 to address residual discharges of acid rock drainage. The Company currently estimates that it will spend between approximately $13.9 million and $18.0 million for remediation at these sites over the next 30 years and has accrued a reserve at the low end of this range. Lead Refinery Site U.S.S. Lead Refinery, Inc. (Lead Refinery), a non-operating wholly owned subsidiary of MRRC, has conducted corrective action and interim remedial activities (collectively, Site Activities) at Lead Refinery’s East Chicago, Indiana site pursuant to the Resource Conservation and Recovery Act since December 1996. Although the Site Activities have been substantially concluded, Lead Refinery is required to perform monitoring and maintenance-related activities pursuant to a post-closure permit issued by the Indiana Department of Environmental Management effective as of March 2, 2013. Approximate costs to comply with the post-closure permit, including associated general and administrative costs, are estimated at between $1.7 million and $2.4 million over the next 16 years. The Company has recorded a reserve at the low end of this range. On April 9, 2009, pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), the U.S. Environmental Protection Agency (EPA) added the Lead Refinery site and surrounding properties to the National Priorities List (NPL). On July 17, 2009, Lead Refinery received a written notice from the EPA indicating that it may be a PRP under CERCLA due to the release or threat of release of hazardous substances including lead into properties surrounding the Lead Refinery NPL site. The EPA identified two other PRPs in connection with that matter. In November 2012, the EPA adopted a remedy for the surrounding properties and in September 2014, the EPA announced that it had entered into a settlement with the two other PRPs whereby they will pay approximately $26.0 million to fund the cleanup of approximately 300 properties surrounding the Lead Refinery NPL site (zones 1 and 3 of operable unit 1) and perform certain remedial action tasks. On November 8, 2016, the Company, its subsidiary Arava Natural Resources Company, Inc. (Arava), and Arava’s subsidiary MRRC each received general notice letters from the EPA asserting that they may be PRPs in connection with the Lead Refinery NPL site. The Company, Arava, and MRRC have denied liability for any remedial action and response costs associated with the Lead Refinery NPL site. In June 2017, the EPA requested that Lead Refinery conduct, and the Company fund, a remedial investigation and feasibility study of operable unit 2 of the Lead Refinery NPL site pursuant to a proposed administrative settlement agreement and order on consent. The Company and Lead Refinery entered into that agreement in September 2017. The Company has made a capital contribution to Lead Refinery to conduct the remedial investigation and feasibility study with respect to operable unit 2 and has provided financial assurance in the amount of $1.0 million. The remedial investigation and feasibility study remain ongoing. The EPA has also asserted its position that Mueller is a responsible party for the Lead Refinery NPL site, and accordingly is responsible for a share of remedial action and response costs at the site and in the adjacent residential area. In January 2018, the EPA issued two unilateral administrative orders (UAOs) directing the Company, Lead Refinery, and four other PRPs to conduct soil and interior remediation of certain residences at the Lead Refinery NPL site (zones 2 and 3 of operable unit 1). The Company and Lead Refinery have reached agreement with the four other PRPs to implement these two UAOs, with the Company agreeing to pay, on an interim basis, (i) an estimated $4.5 million (subject to potential change through a future reallocation process) of the approximately $25.0 million the PRPs currently estimate it will cost to implement the UAOs, which estimate is subject to change, and (ii) $2.0 million relating to past costs incurred by other PRPs for work conducted at the site, as well as the possibility of up to $0.7 million in further payments for ongoing work by those PRPs. As of March 27, 2021, the Company has made payments of approximately $7.5 million related to the aforementioned agreement with the other PRPs. The Company disputes that it was properly named in the UAOs, and has reserved its rights to petition the EPA for reimbursement of any costs incurred to comply with the UAOs upon the completion of the work required therein. In October 2017 and March 2018, separate groups of private plaintiffs sued the Company, Arava, MRRC, and Lead Refinery, along with other defendants, in two civil tort actions relating to the site. The Company, Arava, and MRRC have been voluntarily dismissed from both litigations without prejudice, but Lead Refinery remains a party to each. At this juncture, the Company is unable to determine the likelihood of a material adverse outcome or the amount or range of a potential loss in excess of the current reserve with respect to any remedial action or litigation relating to the Lead Refinery NPL site, either at Lead Refinery’s former operating site (operable unit 2) or the adjacent residential area (operable unit 1), including, but not limited to, EPA oversight costs for which EPA may attempt to seek reimbursement from the Company, and past costs for which other PRPs may attempt to seek contribution from the Company. Bonita Peak Mining District Following an August 2015 spill from the Gold King Mine into the Animas River near Silverton, Colorado, the EPA listed the Bonita Peak Mining District on the NPL. Said listing was finalized in September 2016. The Bonita Peak Mining District encompasses 48 mining sites within the Animas River watershed, including the Sunnyside Mine, the American Tunnel, and the Sunbank Group. On or about July 25, 2017, Washington Mining Company (Washington Mining) (a wholly-owned subsidiary of the Company’s wholly-owned subsidiary, Arava), received a general notice letter from the EPA stating that Washington Mining may be a PRP under CERCLA in connection with the Bonita Peak Mining District site and therefore responsible for the remediation of certain portions of the site, along with related costs incurred by the EPA. Shortly thereafter, the Company received a substantively identical letter asserting that it may be a PRP at the site and similarly responsible for the cleanup of certain portions of the site. The general notice letters identify one other PRP at the site, and do not require specific action by Washington Mining or the Company at this time. At this juncture, the Company is unable to determine the likelihood of a materially adverse outcome or the amount or range of a potential loss with respect to any remedial action related to the Bonita Peak Mining District NPL site. Operating Properties Mueller Copper Tube Products, Inc. In 1999, Mueller Copper Tube Products, Inc. (MCTP), a wholly owned subsidiary, commenced a cleanup and remediation of soil and groundwater at its Wynne, Arkansas plant to remove trichloroethylene, a cleaning solvent formerly used by MCTP. On August 30, 2000, MCTP received approval of its Final Comprehensive Investigation Report and Storm Water Drainage Investigation Report addressing the treatment of soils and groundwater from the Arkansas Department of Environmental Quality (ADEQ). The Company established a reserve for this project in connection with the acquisition of MCTP in 1998. Effective November 17, 2008, MCTP entered into a Settlement Agreement and Administrative Order by Consent to submit a Supplemental Investigation Work Plan (SIWP) and subsequent Final Remediation Work Plan (RWP) for the site. By letter dated January 20, 2010, ADEQ approved the SIWP as submitted, with changes acceptable to the Company. On December 16, 2011, MCTP entered into an amended Administrative Order by Consent to prepare and implement a revised RWP regarding final remediation for the Site. The remediation system was activated in February 2014. Costs to implement the work plans, including associated general and administrative costs, are estimated to approximate $0.9 million to $1.1 million over the next five years. The Company has recorded a reserve at the low end of this range. United States Department of Commerce Antidumping Review On December 24, 2008, the Department of Commerce (DOC) initiated an antidumping administrative review of the antidumping duty order covering circular welded non-alloy steel pipe and tube from Mexico for the November 1, 2007 through October 31, 2008 period of review. The DOC selected Mueller Comercial as a respondent in the review. On April 19, 2010, the DOC published the final results of the review and assigned Mueller Comercial an antidumping duty rate of 48.33 percent. On May 25, 2010, the Company appealed the final results to the U.S. Court of International Trade (CIT). On December 16, 2011, the CIT issued a decision remanding the Department’s final results. While the matter was still pending, the Company and the United States reached an agreement to settle the appeal. Subject to the conditions of the agreement, the Company anticipated that certain of its subsidiaries would incur antidumping duties on subject imports made during the period of review and, as such, established a reserve for this matter. After the lapse of the statutory period of time during which U.S. Customs and Border Protection (CBP) was required, but failed, to liquidate the entries at the settled rate, the Company released the reserve. Between October 30, 2015 and November 27, 2015, CBP sent a series of invoices to Southland Pipe Nipples Co., Inc. (Southland), requesting payment of approximately $3.0 million in duties and interest in connection with 795 import entries made during the November 1, 2007 through October 31, 2008 period. On January 26, 2016 and January 27, 2016, Southland filed protests with CBP in connection with these invoices, noting that CBP’s asserted claims were not made in accordance with applicable law, including statutory provisions governing deemed liquidation. The Company believes in the merits of the legal objections raised in Southland’s protests, and CBP’s response to Southland’s protests is currently pending. Given the procedural posture and issues raised by this legal dispute, the Company cannot estimate the amount of potential duty liability, if any, that may result from CBP’s asserted claims. Deepwater Horizon Economic and Property Damage Claim During 2020, Mueller Copper Tube Company, a wholly owned subsidiary of the Company, collected approximately $22.1 million related to its claim under the Deepwater Horizon Economic and Property Damage Settlement Program. The collected amount represents settlement proceeds received after the payment of fees and expenses. Guarantees Guarantees, in the form of letters of credit, are issued by the Company generally to assure the payment of insurance deductibles, certain retiree health benefits, and debt at certain unconsolidated affiliates. The terms of the guarantees are generally one year but are renewable annually as required. These letters are primarily backed by the Company’s revolving credit facility. The maximum payments that the Company could be required to make under its guarantees at March 27, 2021 were $19.3 million.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 27, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company’s effective tax rate for the first quarter of 2021 was 25 percent compared with 26 percent for the same period last year. The items impacting the effective tax rate for the first quarter of 2021 are primarily related to the provision for state income taxes, net of the federal benefit, of $2.4 million, and other items totaling $0.7 million. The Company’s effective tax rate for the first quarter of 2020 was 26 percent. The items impacting the effective tax rate for the first quarter of 2020 were primarily attributable to the provision for state income taxes, net of the federal benefit, of $2.2 million, and other items of $0.6 million. The Company files a consolidated U.S. federal income tax return and numerous consolidated and separate-company income tax returns in many state, local, and foreign jurisdictions. The statute of limitations is open for the Company’s federal tax return for 2015 and 2017 and all subsequent years. The statutes of limitations for most state returns are open for 2017 and all subsequent years, and some state and foreign returns are also open for some earlier tax years due to differing statute periods. The Internal Revenue Service is auditing the Company’s 2015 and 2017 federal consolidated returns. While the Company believes that it is adequately reserved for possible audit adjustments, the final resolution of these examinations cannot be determined with certainty and could result in final settlements that differ from current estimates.

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	3 Months Ended
	Mar. 27, 2021
Equity [Abstract]
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss)AOCI includes certain foreign currency translation adjustments from those subsidiaries not using the U.S. dollar as their functional currency, net deferred gains and losses on certain derivative instruments accounted for as cash flow hedges, adjustments to pension and OPEB liabilities, and other comprehensive income attributable to unconsolidated affiliates. The following tables provide changes in AOCI by component, net of taxes and noncontrolling interests (amounts in parentheses indicate debits to AOCI): For the Quarter Ended March 27, 2021 (In thousands) Cumulative Translation Adjustment Unrealized Gain (Loss) on Derivatives Pension/OPEB Liability Adjustment Attributable to Unconsol. Affiliates Total Balance as of December 26, 2020 $ (37,339) $ 984 $ (17,203) $ (1,325) $ (54,883) Other comprehensive income (loss) before reclassifications 3,966 1,488 (283) 1,987 7,158 Amounts reclassified from AOCI — (995) 192 — (803) Net current-period other comprehensive income (loss) 3,966 493 (91) 1,987 6,355 Balance as of March 27, 2021 $ (33,373) $ 1,477 $ (17,294) $ 662 $ (48,528) For the Quarter Ended March 28, 2020 (In thousands) Cumulative Translation Adjustment Unrealized Gain (Loss) on Derivatives Pension/OPEB Liability Adjustment Attributable to Unconsol. Affiliates Total Balance as of December 28, 2019 $ (46,198) $ 476 $ (21,855) $ (1,193) $ (68,770) Other comprehensive (loss) income before reclassifications (20,664) (3,735) 587 1,887 (21,925) Amounts reclassified from AOCI — 378 152 — 530 Net current-period other comprehensive (loss) income (20,664) (3,357) 739 1,887 (21,395) Balance as of March 28, 2020 $ (66,862) $ (2,881) $ (21,116) $ 694 $ (90,165) Reclassification adjustments out of AOCI were as follows: Amount reclassified from AOCI For the Quarter Ended (In thousands) March 27, 2021 March 28, 2020 Affected line item Unrealized (gains) losses on derivative commodity contracts $ (1,299) $ 468 Cost of goods sold 304 (90) Income tax expense (benefit) $ (995) $ 378 Net of tax and noncontrolling interests Amortization of net loss and prior service cost on employee benefit plans $ 229 $ 181 Other income, net (37) (29) Income tax benefit $ 192 $ 152 Net of tax and noncontrolling interests

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 27, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On March 31, 2021, the Company entered into a Credit Agreement to replace its prior credit agreement that would have matured on December 6, 2021. The Company's total borrowing capacity under the Credit Agreement is $500.0 million. The Credit Agreement provides for an unsecured $400.0 million revolving credit facility, which matures March 31, 2026, and a term loan facility of $100.0 million, which matures March 31, 2022. Funds borrowed under the Credit Agreement may be used by the Company for working capital purposes and other general corporate purposes. In addition, the Credit Agreement provides a sublimit of $50.0 million for the issuance of letters of credit, a sublimit of $35.0 million for loans and letters of credit made in certain foreign currencies, and a Swing Line sublimit of $25.0 million. Outstanding letters of credit and foreign currency loans reduce borrowing availability under the Credit Agreement on a dollar-for-dollar basis. During the first quarter of 2021, the Company announced the redemption of its Subordinated Debentures due 2027. The full redemption of outstanding debentures occurred on April 15, 2021 for a total of $291.4 million in principal plus accrued interest and a redemption premium of $5.7 million.

Recent Accounting Standards (Po

Recent Accounting Standards (Policies)	3 Months Ended
	Mar. 27, 2021
Accounting Changes and Error Corrections [Abstract]
Recently Adopted and Issued Accounting Standards	Adopted In October 2020, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2020-10, Codification Improvements: An Amendment of the FASB Accounting Standards Codification . The ASU facilitates updates to the Accounting Standards Codification for technical corrections such as conforming amendments, clarifications to guidance, simplifications to wording or structure of guidance, and other minor improvements. The Company adopted the ASU during the first quarter of 2021 using a retrospective approach. The adoption of the ASU did not have a material impact on the Company’s Condensed Consolidated Financial Statements. In January 2020, the FASB issued ASU No. 2020-01, Investments - Equity Securities (Topic 321), Investments - Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815): Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 . The new guidance addresses accounting for the transition into and out of the equity method and measuring certain purchased options and forward contracts to acquire investments. The Company adopted the ASU during the first quarter of 2021 using a prospective approach. The adoption of the ASU did not have a material impact on the Company’s Condensed Consolidated Financial Statements. In December 2019, the FASB issued ASU No. 2019-12, Income Taxes: Simplifying the Accounting for Income Taxes . The new guidance affects general principles within Topic 740, Income Taxes. The amendments of ASU 2019-12 are meant to simplify and reduce the cost of accounting for income taxes. The Company adopted the ASU during the first quarter of 2021 using a prospective approach. The adoption of the ASU did not have a material impact on the Company’s Condensed Consolidated Financial Statements. Issued In January 2021, the FASB issued ASU No. 2021-01, Reference Rate Reform (Topic 848): An Amendment of the FASB Accounting Standards Codification. The new guidance was issued in response to concerns about structural risks of interbank offered rates, and, particularly, the risk of cessation of the London Interbank Offered Rate (LIBOR). Regulators in numerous jurisdictions around the world have undertaken reference rate reform initiatives to identify alternative reference rates that are more observable or transaction based and less susceptible to manipulation. The ASU is effective in 2021 but can be applied through December 31, 2022. The updated guidance requires retrospective adoption, and early adoption is permitted. The Company does not expect the adoption of the ASU to have a material impact on its Condensed Consolidated Financial Statements.

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
	Mar. 27, 2021
Segment Reporting [Abstract]
Summary of Segment Information	Summarized segment information is as follows: For the Quarter Ended March 27, 2021 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 547,748 $ 164,852 $ 111,026 $ (5,478) $ 818,148 Cost of goods sold 450,354 140,891 84,082 (6,909) 668,418 Depreciation and amortization 6,210 1,743 2,629 1,173 11,755 Selling, general, and administrative expense 24,086 3,371 6,980 10,998 45,435 Operating income 67,098 18,847 17,335 (10,740) 92,540 Interest expense (4,469) Other income, net 577 Income before income taxes $ 88,648 Segment information (continued): For the Quarter Ended March 28, 2020 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 385,013 $ 131,202 $ 93,272 $ (6,568) $ 602,919 Cost of goods sold 319,164 114,797 71,093 3,661 508,715 Depreciation and amortization 5,699 2,002 2,466 872 11,039 Selling, general, and administrative expense 20,439 3,221 6,699 12,393 42,752 Asset impairments 3,035 — — — 3,035 Litigation settlement, net — — — (21,933) (21,933) Operating income 36,676 11,182 13,014 (1,561) 59,311 Interest expense (5,379) Other income, net 278 Income before income taxes $ 54,210
Disaggregation of Revenue From Contracts with Customers	The following tables represent a disaggregation of revenue from contracts with customers, along with the reportable segment for each category: For the Quarter Ended March 27, 2021 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 426,139 $ — $ — $ 426,139 Brass rod and forgings — 131,262 — 131,262 OEM components, tube & assemblies 8,555 11,033 38,067 57,655 Valves and plumbing specialties 113,054 — — 113,054 Other — 22,557 72,959 95,516 547,748 164,852 111,026 823,626 Intersegment sales (5,478) Net sales $ 818,148 Disaggregation of revenue from contracts with customers (continued): For the Quarter Ended March 28, 2020 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 302,129 $ — $ — $ 302,129 Brass rod and forgings — 99,670 — 99,670 OEM components, tube & assemblies 25,295 10,882 36,573 72,750 Valves and plumbing specialties 57,589 — — 57,589 Other — 20,650 56,699 77,349 385,013 131,202 93,272 609,487 Intersegment sales (6,568) Net sales $ 602,919

Cash, Cash Equivalents, and R_2

Cash, Cash Equivalents, and Restricted Cash (Tables)	3 Months Ended
	Mar. 27, 2021
Cash and Cash Equivalents [Abstract]
Schedule of Cash and Cash Equivalents	(In thousands) March 27, December 26, Cash & cash equivalents $ 129,876 $ 119,075 Restricted cash included within other current assets 19,052 8,198 Restricted cash included within other assets 103 103 Total cash, cash equivalents, and restricted cash $ 149,031 $ 127,376
Restrictions on Cash and Cash Equivalents	(In thousands) March 27, December 26, Cash & cash equivalents $ 129,876 $ 119,075 Restricted cash included within other current assets 19,052 8,198 Restricted cash included within other assets 103 103 Total cash, cash equivalents, and restricted cash $ 149,031 $ 127,376

Inventories (Tables)

Inventories (Tables)	3 Months Ended
	Mar. 27, 2021
Inventory Disclosure [Abstract]
Inventories	(In thousands) March 27, December 26, Raw materials and supplies $ 119,196 $ 85,927 Work-in-process 52,803 49,361 Finished goods 201,748 186,785 Valuation reserves (8,290) (7,071) Inventories $ 365,457 $ 315,002

Financial Instruments (Tables)

Financial Instruments (Tables)	3 Months Ended
	Mar. 27, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments Designated as Cash Flow Hedges Reflected in the Financial Statements	The following table summarizes the location and fair value of the derivative instruments and disaggregates the net derivative assets and liabilities into gross components on a contract-by-contract basis: Asset Derivatives Liability Derivatives Fair Value Fair Value (In thousands) Balance Sheet Location March 27, December 26, Balance Sheet Location March 27, December 26, Commodity contracts - gains Other current assets $ 1,965 $ 1,213 Other current liabilities $ — $ 68 Commodity contracts - losses Other current assets (55) (8) Other current liabilities (14,667) (5,863) Total derivatives (1) $ 1,910 $ 1,205 $ (14,667) $ (5,795) (1) Does not include the impact of cash collateral provided to counterparties.
Schedule of Fair Value Hedges	The following tables summarize the effects of derivative instruments on the Company’s Condensed Consolidated Statements of Income: For the Quarter Ended (In thousands) Location March 27, 2021 March 28, 2020 Undesignated derivatives: Loss on commodity contracts (nonqualifying) Cost of goods sold (8,530) (9,476)
Summary of Activities Related to Derivative Instruments Classified as Cash Flow Hedges	The following tables summarize amounts recognized in and reclassified from AOCI during the period: For the Quarter Ended March 27, 2021 (In thousands) Gain (Loss) Recognized in AOCI (Effective Portion), Net of Tax Classification Gains (Losses) (Gain) Loss Reclassified from AOCI (Effective Portion), Net of Tax Cash flow hedges: Commodity contracts $ 1,491 Cost of goods sold $ (996) Other (3) Other 1 Total $ 1,488 Total $ (995) For the Quarter Ended March 28, 2020 (In thousands) Loss Recognized in AOCI (Effective Portion), Net of Tax Classification Gains (Losses) Loss Reclassified from AOCI (Effective Portion), Net of Tax Cash flow hedges: Commodity contracts $ (3,706) Cost of goods sold $ 378 Other (29) Other — Total $ (3,735) Total $ 378

Investments in Unconsolidated_2

Investments in Unconsolidated Affiliates (Tables)	3 Months Ended
	Mar. 27, 2021
Equity Method Investments and Joint Ventures [Abstract]
Summarized Financial Information Derived From the Company's Equity Method Investee's Consolidated Financial Statements	The following tables present summarized financial information derived from the Company’s equity method investees’ combined consolidated financial statements, which are prepared in accordance with U.S. GAAP. (In thousands) March 27, December 26, Current assets $ 171,907 $ 167,451 Noncurrent assets 82,198 78,241 Current liabilities 127,317 120,202 Noncurrent liabilities 49,463 50,020 For the Quarter Ended (In thousands) March 27, 2021 March 28, 2020 Net sales $ 97,329 $ 106,998 Gross profit 9,699 13,486 Net loss (3,299) (12,685)

Benefit Plans (Tables)

Benefit Plans (Tables)	3 Months Ended
	Mar. 27, 2021
Retirement Benefits [Abstract]
Components of Net Periodic Benefit Cost (Income)	The components of net periodic benefit cost (income) are as follows: For the Quarter Ended (In thousands) March 27, 2021 March 28, 2020 Pension benefits: Interest cost $ 313 $ 858 Expected return on plan assets (904) (1,495) Amortization of net loss 378 460 Net periodic benefit income $ (213) $ (177) Other benefits: Service cost $ 65 $ 61 Interest cost 87 109 Amortization of prior service credit (118) (226) Amortization of net gain (31) (53) Net periodic benefit cost (income) $ 3 $ (109)

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	3 Months Ended
	Mar. 27, 2021
Equity [Abstract]
Changes in AOCI by Component, Net of Taxes and Noncontrolling Interest	The following tables provide changes in AOCI by component, net of taxes and noncontrolling interests (amounts in parentheses indicate debits to AOCI): For the Quarter Ended March 27, 2021 (In thousands) Cumulative Translation Adjustment Unrealized Gain (Loss) on Derivatives Pension/OPEB Liability Adjustment Attributable to Unconsol. Affiliates Total Balance as of December 26, 2020 $ (37,339) $ 984 $ (17,203) $ (1,325) $ (54,883) Other comprehensive income (loss) before reclassifications 3,966 1,488 (283) 1,987 7,158 Amounts reclassified from AOCI — (995) 192 — (803) Net current-period other comprehensive income (loss) 3,966 493 (91) 1,987 6,355 Balance as of March 27, 2021 $ (33,373) $ 1,477 $ (17,294) $ 662 $ (48,528) For the Quarter Ended March 28, 2020 (In thousands) Cumulative Translation Adjustment Unrealized Gain (Loss) on Derivatives Pension/OPEB Liability Adjustment Attributable to Unconsol. Affiliates Total Balance as of December 28, 2019 $ (46,198) $ 476 $ (21,855) $ (1,193) $ (68,770) Other comprehensive (loss) income before reclassifications (20,664) (3,735) 587 1,887 (21,925) Amounts reclassified from AOCI — 378 152 — 530 Net current-period other comprehensive (loss) income (20,664) (3,357) 739 1,887 (21,395) Balance as of March 28, 2020 $ (66,862) $ (2,881) $ (21,116) $ 694 $ (90,165)
Reclassification Adjustments Out of AOCI	Reclassification adjustments out of AOCI were as follows: Amount reclassified from AOCI For the Quarter Ended (In thousands) March 27, 2021 March 28, 2020 Affected line item Unrealized (gains) losses on derivative commodity contracts $ (1,299) $ 468 Cost of goods sold 304 (90) Income tax expense (benefit) $ (995) $ 378 Net of tax and noncontrolling interests Amortization of net loss and prior service cost on employee benefit plans $ 229 $ 181 Other income, net (37) (29) Income tax benefit $ 192 $ 152 Net of tax and noncontrolling interests

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - USD ($) $ in Millions	Jan. 29, 2021	Aug. 03, 2020	Jan. 17, 2020	Mar. 27, 2021
Hart & Cooley Flexible Duct Business [Member]
Business Acquisition [Line Items]
Consideration transferred net of working capital adjustments	$ 14
Fair value of assets acquired	12.9
Fair value of property, plant and equipment acquired	8.4
Fair value of inventories acquired	4.5
Tax-deductible goodwill	$ 1.1
Wieland-Kessler LLC [Member]
Business Acquisition [Line Items]
Consideration transferred net of working capital adjustments		$ 57.2
Fair value of assets acquired		28.7
Tax-deductible goodwill		$ 28.5
Increase in intangible assets				$ 1.5
Decrease in goodwill				$ 1.5
Shoals Tubular, Inc. [Member]
Business Acquisition [Line Items]
Consideration transferred net of working capital adjustments			$ 15.3
Fair value of assets acquired			6.2
Fair value of property, plant and equipment acquired			3.7
Fair value of inventories acquired			1.8
Tax-deductible goodwill			9.3
Cash portion of acquisition price			15.3
Fair value of accounts receivable acquired			0.7
Fair value of liabilities acquired			$ 0.2

Segment Information - Summary o

Segment Information - Summary of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Summary of segment information [Abstract]
Net sales	$ 818,148	$ 602,919
Cost of goods sold	668,418	508,715
Depreciation and amortization	11,755	11,039
Selling, general, and administrative expense	45,435	42,752
Asset impairments	0	3,035
Litigation settlement, net	0	(21,933)
Operating income	92,540	59,311
Interest expense	(4,469)	(5,379)
Other income (expense), net	577	278
Income before income taxes	88,648	54,210
Operating Segments [Member]
Summary of segment information [Abstract]
Net sales	823,626	609,487
Operating Segments [Member] | Piping Systems [Member]
Summary of segment information [Abstract]
Net sales	547,748	385,013
Cost of goods sold	450,354	319,164
Depreciation and amortization	6,210	5,699
Selling, general, and administrative expense	24,086	20,439
Asset impairments		3,035
Litigation settlement, net		0
Operating income	67,098	36,676
Operating Segments [Member] | Industrial Metals [Member]
Summary of segment information [Abstract]
Net sales	164,852	131,202
Cost of goods sold	140,891	114,797
Depreciation and amortization	1,743	2,002
Selling, general, and administrative expense	3,371	3,221
Asset impairments		0
Litigation settlement, net		0
Operating income	18,847	11,182
Operating Segments [Member] | Climate [Member]
Summary of segment information [Abstract]
Net sales	111,026	93,272
Cost of goods sold	84,082	71,093
Depreciation and amortization	2,629	2,466
Selling, general, and administrative expense	6,980	6,699
Asset impairments		0
Litigation settlement, net		0
Operating income	17,335	13,014
Corporate and Eliminations [Member]
Summary of segment information [Abstract]
Net sales	(5,478)	(6,568)
Cost of goods sold	(6,909)	3,661
Depreciation and amortization	1,173	872
Selling, general, and administrative expense	10,998	12,393
Asset impairments		0
Litigation settlement, net		(21,933)
Operating income	$ (10,740)	$ (1,561)

Segment Information - Net Sales

Segment Information - Net Sales by Major Product Line (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ 818,148	$ 602,919
Operating Segments [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	823,626	609,487
Operating Segments [Member] | Piping Systems [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	547,748	385,013
Operating Segments [Member] | Industrial Metals [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	164,852	131,202
Operating Segments [Member] | Climate [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	111,026	93,272
Operating Segments [Member] | Tube and fittings [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	426,139	302,129
Operating Segments [Member] | Tube and fittings [Member] | Piping Systems [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	426,139	302,129
Operating Segments [Member] | Tube and fittings [Member] | Industrial Metals [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	0	0
Operating Segments [Member] | Tube and fittings [Member] | Climate [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	0	0
Operating Segments [Member] | Brass rod and forgings [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	131,262	99,670
Operating Segments [Member] | Brass rod and forgings [Member] | Piping Systems [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	0	0
Operating Segments [Member] | Brass rod and forgings [Member] | Industrial Metals [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	131,262	99,670
Operating Segments [Member] | Brass rod and forgings [Member] | Climate [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	0	0
Operating Segments [Member] | OEM components, tube and assemblies [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	57,655	72,750
Operating Segments [Member] | OEM components, tube and assemblies [Member] | Piping Systems [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	8,555	25,295
Operating Segments [Member] | OEM components, tube and assemblies [Member] | Industrial Metals [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	11,033	10,882
Operating Segments [Member] | OEM components, tube and assemblies [Member] | Climate [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	38,067	36,573
Operating Segments [Member] | Valves and plumbing specialties [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	113,054	57,589
Operating Segments [Member] | Valves and plumbing specialties [Member] | Piping Systems [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	113,054	57,589
Operating Segments [Member] | Valves and plumbing specialties [Member] | Industrial Metals [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	0	0
Operating Segments [Member] | Valves and plumbing specialties [Member] | Climate [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	0	0
Operating Segments [Member] | Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	95,516	77,349
Operating Segments [Member] | Other [Member] | Piping Systems [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	0	0
Operating Segments [Member] | Other [Member] | Industrial Metals [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	22,557	20,650
Operating Segments [Member] | Other [Member] | Climate [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	72,959	56,699
Intersegment Sales [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales	$ (5,478)	$ (6,568)

Cash, Cash Equivalents, and R_3

Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020	Mar. 28, 2020	Dec. 28, 2019
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 129,876	$ 119,075
Restricted cash included within other current assets	19,052	8,198
Restricted cash included within other assets	103	103
Total cash, cash equivalents, and restricted cash	$ 149,031	$ 127,376	$ 171,964	$ 98,042

Inventories (Details)

Inventories (Details) - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 119,196	$ 85,927
Work-in-process	52,803	49,361
Finished goods	201,748	186,785
Valuation reserves	(8,290)	(7,071)
Inventories	$ 365,457	$ 315,002

Financial Instruments - Narrati

Financial Instruments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 27, 2021	Dec. 26, 2020
Derivative [Line Items]
Restricted cash in other current assets as collateral related to open derivative contracts	$ 18.6	$ 7.6
Commodity Contracts [Member]
Derivative [Line Items]
Deferred net gains (losses), net of tax, included in AOCI	1.3
Cash Flow Hedging [Member] | Commodity Contracts [Member] | Long [Member]
Derivative [Line Items]
Open option contracts written, at fair value	$ 21.2
Time period for open copper future contract purchases	14 months
Fair value of future contracts with net gain (loss) position	$ 1.9
Fair Value Hedging [Member] | Commodity Contracts [Member] | Short [Member]
Derivative [Line Items]
Fair value of future contracts with net gain (loss) position	(14.6)
Open future contracts to sell copper	$ 70.8
Time period for open copper future contract sales	6 months

Financial Instruments - Summary

Financial Instruments - Summary of Location and Fair Value (Details) - Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Mar. 27, 2021	Dec. 26, 2020
Derivatives, Fair Value [Line Items]
Total derivative assets	$ 1,910	$ 1,205
Total derivative liabilities	(14,667)	(5,795)
Other Current Assets [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Other current assets: Gain positions	1,965	1,213
Other current assets: Loss positions	(55)	(8)
Other Current Liabilities [Member] | Commodity Contracts [Member]
Derivatives, Fair Value [Line Items]
Other current liability: Gain positions	0	68
Other current liability: Loss positions	$ (14,667)	$ (5,863)

Financial Instruments - Effects

Financial Instruments - Effects of Derivative Instruments on Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Commodity Contracts [Member] | Cost of Goods Sold [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss on commodity contracts (nonqualifying)	$ (8,530)	$ (9,476)

Financial Instruments - Amounts

Financial Instruments - Amounts Recognized in and Reclassified from AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI (Effective Portion), Net of Tax	$ 493	$ (3,357)
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI (Effective Portion), Net of Tax	1,488	(3,735)
(Gain) Loss Reclassified from AOCI (Effective Portion), Net of Tax	(995)	378
Commodity Contracts [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI (Effective Portion), Net of Tax	1,491	(3,706)
Commodity Contracts [Member] | Cash Flow Hedging [Member] | Cost of Goods Sold [Member]
Derivative Instruments, Gain (Loss) [Line Items]
(Gain) Loss Reclassified from AOCI (Effective Portion), Net of Tax	(996)	378
Other [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in AOCI (Effective Portion), Net of Tax	(3)	(29)
(Gain) Loss Reclassified from AOCI (Effective Portion), Net of Tax	$ 1	$ 0

Investments in Unconsolidated_3

Investments in Unconsolidated Affiliates - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		63 Months Ended
	Mar. 27, 2021	Mar. 28, 2020	Mar. 27, 2021
Schedule of Equity Method Investments [Line Items]
Net income (loss)	$ 65,238	$ 33,951
Tecumseh Products Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in the joint venture, ownership percentage	50.00%		50.00%
Net income (loss)	$ (1,600)	$ (6,300)
Second Unconsolidated Affiliate [Member]
Schedule of Equity Method Investments [Line Items]
Interest in the joint venture, ownership percentage	50.00%		50.00%
Mueller Middle East [Member]
Schedule of Equity Method Investments [Line Items]
Interest in the joint venture, ownership percentage	40.00%		40.00%
Cash invested to acquire joint venture interest			$ 5,000

Investments in Unconsolidated_4

Investments in Unconsolidated Affiliates - Summarized Financial Information Derived from Equity Method Investees' Consolidated Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020	Dec. 26, 2020
Balance sheet data [Abstract]
Current assets	$ 986,535		$ 825,361
Current liabilities	444,488		339,643
Income Statement [Abstract]
Net sales	818,148	$ 602,919
Net income (loss)	65,238	33,951
Tecumseh
Balance sheet data [Abstract]
Current assets	171,907		167,451
Noncurrent assets	82,198		78,241
Current liabilities	127,317		120,202
Noncurrent liabilities	49,463		$ 50,020
Income Statement [Abstract]
Net sales	97,329	106,998
Gross profit	9,699	13,486
Net income (loss)	$ (3,299)	$ (12,685)

Benefit Plans (Details)

Benefit Plans (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Pension Benefits [Member]
Components of net periodic benefit cost (income) [Abstract]
Interest cost	$ 313	$ 858
Expected return on plan assets	(904)	(1,495)
Amortization of net loss (gain)	378	460
Net periodic benefit income	(213)	(177)
Other Benefits [Member]
Components of net periodic benefit cost (income) [Abstract]
Interest cost	87	109
Amortization of net loss (gain)	(31)	(53)
Service cost	65	61
Amortization of prior service credit	(118)	(226)
Net periodic benefit income	$ 3	$ (109)

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2018USD ($)potentially_responsible_partyunilateral_administrative_order	Nov. 27, 2015USD ($)	Mar. 27, 2021USD ($)propertysmelter_site	Oct. 31, 2008Import_entry	Mar. 27, 2021potentially_responsible_party	Mar. 27, 2021USD ($)	Feb. 12, 2020USD ($)	Nov. 08, 2016USD ($)	Apr. 19, 2010
Loss Contingencies [Line Items]
Term of guarantees			1 year
Payments required to be made under guarantees, maximum						$ 19.3
United States Department of Commerce Antidumping Review [Member]
Loss Contingencies [Line Items]
Assignment of antidumping duty rate on U.S. imports by Company subsidiaries (as a percent)									48.33%
Payment for interest and duties		$ 3
Number of import entries | Import_entry				795
Deepwater Horizon Economic and Property Damage Claim [Member]
Loss Contingencies [Line Items]
Amount awarded to the Company							$ 22.1
Lead Refinery Site [Member]
Loss Contingencies [Line Items]
Financial guarantee								$ 1
Lead Refinery NPL Site [Member]
Loss Contingencies [Line Items]
Environmental reserves	$ 4.5
Number of UAOs | unilateral_administrative_order	2
Number of PRPs | potentially_responsible_party	4
Site contingency, total costs	$ 25
Site contingency, amount agreed upon to pay PRPs for past costs	2
Site contingency, additional reimbursement of past costs	$ 0.7
Contingency charge			$ 7.5
Non operating Properties [Member] | Southeast Kansas Sites [Member]
Loss Contingencies [Line Items]
Number of parties involved in settlement negotiations			3		2
Environmental reserves						$ 5.6
Non operating Properties [Member] | Shasta Area Mine Sites [Member]
Loss Contingencies [Line Items]
Period of permit, implementation of Best Management Practices			10 years
Estimated remediation costs, term			30 years
Non operating Properties [Member] | Lead Refinery Site [Member]
Loss Contingencies [Line Items]
Number of parties involved in settlement negotiations | potentially_responsible_party					2
Estimated remediation costs, term			16 years
Amount other PRPs will pay to fund cleanup			$ 26
Number of surrounding properties | property			300
Non operating Properties [Member] | Minimum [Member] | Shasta Area Mine Sites [Member]
Loss Contingencies [Line Items]
Estimated remediation costs			$ 13.9
Non operating Properties [Member] | Minimum [Member] | Lead Refinery Site [Member]
Loss Contingencies [Line Items]
Estimated remediation costs			1.7
Non operating Properties [Member] | Maximum [Member] | Shasta Area Mine Sites [Member]
Loss Contingencies [Line Items]
Estimated remediation costs			18
Non operating Properties [Member] | Maximum [Member] | Lead Refinery Site [Member]
Loss Contingencies [Line Items]
Estimated remediation costs			$ 2.4
Operating Properties [Member] | Mueller Copper Tube Products, Inc. [Member]
Loss Contingencies [Line Items]
Estimated remediation costs, term			5 years
Operating Properties [Member] | Minimum [Member] | Mueller Copper Tube Products, Inc. [Member]
Loss Contingencies [Line Items]
Estimated remediation costs			$ 0.9
Operating Properties [Member] | Maximum [Member] | Mueller Copper Tube Products, Inc. [Member]
Loss Contingencies [Line Items]
Estimated remediation costs			$ 1.1

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Income Tax Disclosure [Abstract]
Effective tax rate	25.00%	26.00%
Provision for state income taxes, net of federal benefits	$ 2.4	$ 2.2
Other items	$ 0.7	$ 0.6

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Changes in AOCI by Component (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of period	$ 801,060
Total other comprehensive income (loss), net	6,776	$ (21,986)
Balance at end of period	868,013
Cumulative Translation Adjustment [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of period	(37,339)	(46,198)
Other comprehensive income (loss) before reclassifications	3,966	(20,664)
Amounts reclassified from AOCI	0	0
Total other comprehensive income (loss), net	3,966	(20,664)
Balance at end of period	(33,373)	(66,862)
Unrealized (Loss) Gain on Derivatives [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of period	984	476
Other comprehensive income (loss) before reclassifications	1,488	(3,735)
Amounts reclassified from AOCI	(995)	378
Total other comprehensive income (loss), net	493	(3,357)
Balance at end of period	1,477	(2,881)
Pension/OPEB Liability Adjustment [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of period	(17,203)	(21,855)
Other comprehensive income (loss) before reclassifications	(283)	587
Amounts reclassified from AOCI	192	152
Total other comprehensive income (loss), net	(91)	739
Balance at end of period	(17,294)	(21,116)
Attributable to Unconsolidated Affiliates [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of period	(1,325)	(1,193)
Other comprehensive income (loss) before reclassifications	1,987	1,887
Amounts reclassified from AOCI	0	0
Total other comprehensive income (loss), net	1,987	1,887
Balance at end of period	662	694
Total [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of period	(54,883)	(68,770)
Other comprehensive income (loss) before reclassifications	7,158	(21,925)
Amounts reclassified from AOCI	(803)	530
Total other comprehensive income (loss), net	6,355	(21,395)
Balance at end of period	$ (48,528)	$ (90,165)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Reclassification Adjustments Out of AOCI (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of goods sold	$ 668,418	$ 508,715
Income tax expense (benefit)	21,761	14,144
Net of tax and noncontrolling interests	(63,107)	(32,415)
Other income, net	(577)	(278)
Unrealized (gains) losses on derivative commodity contracts [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Cost of goods sold	(1,299)	468
Income tax expense (benefit)	304	(90)
Net of tax and noncontrolling interests	(995)	378
Amortization of net loss and prior service cost on employee benefit plans [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax expense (benefit)	(37)	(29)
Net of tax and noncontrolling interests	192	152
Other income, net	$ 229	$ 181

Subsequent Events (Details)

Subsequent Events (Details) - Subsequent Event - USD ($)	Apr. 15, 2021	Mar. 31, 2021
Line of Credit
Subsequent Event [Line Items]
Maximum borrowing capacity		$ 500,000,000
Subordinated Debt
Subsequent Event [Line Items]
Repayments of debt	$ 291,400,000
Redemption premium	$ 5,700,000
Revolving Credit Facility | Line of Credit
Subsequent Event [Line Items]
Maximum borrowing capacity		400,000,000
Term Loan Facility | Line of Credit
Subsequent Event [Line Items]
Maximum borrowing capacity		100,000,000
Letter of Credit | Line of Credit
Subsequent Event [Line Items]
Maximum borrowing capacity		50,000,000
Letter of Credit | Foreign Line of Credit
Subsequent Event [Line Items]
Maximum borrowing capacity		35,000,000
Bridge Loan | Line of Credit
Subsequent Event [Line Items]
Maximum borrowing capacity		$ 25,000,000