Mueller Industries (MLI) 10-K 27 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 29, 2018	Feb. 22, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	MUELLER INDUSTRIES INC
Entity Central Index Key	89,439
Current Fiscal Year End Date	--12-29
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 1,675,560,572
Entity Common Stock, Shares Outstanding		56,624,284
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 29, 2018

CONSOLIDATED STATEMENTS OF INCO

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	[1]	Dec. 31, 2016	[1]
Income Statement [Abstract]
Net sales	$ 2,507,878	$ 2,266,073		$ 2,055,622
Cost of goods sold	2,150,400	1,940,617		1,723,499
Depreciation and amortization	39,555	33,944		35,133
Selling, general, and administrative expense	148,888	140,730		135,811
Gain on sale of assets, net	(253)	(1,491)	[2]	0	[2]
Impairment charges	0	1,466	[2]	6,778	[2]
Insurance recovery	(3,681)	0		0
Operating income	172,969	150,807		154,401
Interest expense	(25,199)	(19,502)		(7,387)
Environmental expense	(1,320)	(7,284)		(1,279)
Other income, net	3,967	2,951		295
Income before income taxes	150,417	126,972		146,030
Income tax expense	(30,952)	(37,884)		(48,137)
(Loss) income from unconsolidated affiliates, net of foreign tax	(12,645)	(2,077)	[2]	1,861	[2]
Consolidated net income	106,820	87,011	[2]	99,754	[2]
Net income attributable to noncontrolling interests	(2,361)	(1,413)		(27)
Net income attributable to Mueller Industries, Inc.	$ 104,459	$ 85,598		$ 99,727
Weighted average shares for basic earnings per share (in shares)	56,782	56,925		56,572
Effect of dilutive stock-based awards (in shares)	487	559		597
Adjusted weighted average shares for diluted earnings per share (in shares)	57,269	57,484		57,169
Basic earnings per share (in dollars per share)	$ 1.84	$ 1.50		$ 1.76
Diluted earnings per share (in dollars per share)	1.82	1.49		1.74
Dividends per share (in dollars per share)	$ 0.4	$ 8.4		$ 0.375
[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.

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Consolidated net income	$ 106,820	$ 87,011	[1],[2]	$ 99,754	[1],[2]
Other comprehensive (loss) income, net of tax:
Foreign currency translation	(16,876)	13,174		(27,767)
Net change with respect to derivative instruments and hedging activities, net of tax of $318, $(541), and $(917)	(1,173)	1,147		1,709
Net change in pension and postretirement obligation adjustments, net of tax of $670, $(1,071), and $(2,606)	(3,339)	2,436		5,383
Attributable to unconsolidated affiliates, net of tax of $2,522, $(505), and $(3,375)	(8,686)	895		5,975
Other, net	0	(380)		159
Total other comprehensive (loss) income, net	(30,074)	17,272		(14,541)
Consolidated comprehensive income	76,746	104,283		85,213
Comprehensive (income) loss attributable to noncontrolling interests	(1,579)	(2,785)		2,548
Comprehensive income attributable to Mueller Industries, Inc.	$ 75,167	$ 101,498		$ 87,761
[1]	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.
[2]	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.

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Derivative instruments, tax	$ 318	$ (541)	$ (917)
Pension & OPEB obligations, tax	670	(1,071)	(2,606)
Attributable to unconsolidated affiliates, tax	$ 2,522	$ (505)	$ (3,375)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Current assets:
Cash and cash equivalents	$ 72,616	$ 120,269
Accounts receivable, less allowance for doubtful accounts of $836 in 2018 and $980 in 2017	273,417	244,795
Inventories	329,795	327,901
Other current assets	26,790	46,150
Total current assets	702,618	739,115
Property, plant, and equipment, net	370,633	304,321
Goodwill, net	150,335	130,293
Intangible assets, net	61,971	42,008
Investment in unconsolidated affiliates	58,042	76,434
Other noncurrent assets	25,950	28,002
Total Assets	1,369,549	1,320,173
Current liabilities:
Current portion of debt	7,101	16,480
Accounts payable	103,754	102,503
Accrued wages and other employee costs	38,549	33,546
Other current liabilities	83,397	89,723
Total current liabilities	232,801	242,252
Long-term debt, less current portion	489,597	448,592
Pension liabilities	14,237	11,606
Postretirement benefits other than pensions	14,818	17,107
Environmental reserves	20,009	23,699
Deferred income taxes	16,615	19,403
Other noncurrent liabilities	18,212	21,486
Total liabilities	806,289	784,145
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 56,702,997 in 2018 and 57,809,509 in 2017	802	802
Additional paid-in capital	276,849	274,585
Retained earnings	824,737	743,503
Accumulated other comprehensive loss	(79,792)	(51,056)
Treasury common stock, at cost	(474,240)	(445,723)
Total Mueller Industries, Inc. stockholders' equity	548,356	522,111
Noncontrolling interests	14,904	13,917
Total equity	563,260	536,028
Commitments and contingencies
Total Liabilities and Equity	$ 1,369,549	$ 1,320,173

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 836	$ 980
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)	56,702,997	57,809,509

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands		12 Months Ended
		Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016
Operating activities:
Consolidated net income		$ 106,820	$ 87,011	[1],[2]	$ 99,754	[1],[2]
Reconciliation of consolidated net income to net cash provided by operating activities:
Depreciation		35,118	30,800	[1]	30,827	[1]
Amortization of intangibles		4,437	3,144	[1]	4,306	[1]
Amortization of debt issuance costs		318	303	[1]	569	[1]
Loss (income) from unconsolidated affiliates		12,645	2,077	[1],[2]	(1,861)	[1],[2]
Insurance proceeds - noncapital related		2,306	500	[1]	0	[1]
Insurance recovery		(3,681)	0	[1]	0	[1]
Stock-based compensation expense		8,035	7,450	[1]	6,387	[1]
Gain on sale of business		0	(1,491)		0
Gain on disposals of assets		(253)	(624)	[1]	(651)	[1]
Impairment charges		0	1,466	[1],[2]	6,778	[1],[2]
Deferred income tax expense (benefit)		170	(3,160)	[1]	6,998	[1]
Recovery of doubtful accounts receivable		0	0	[1]	(50)	[1]
Changes in assets and liabilities, net of effects of businesses acquired and sold:
Receivables		(11,342)	(1,779)	[1]	(16,502)	[1]
Inventories		27,512	(86,286)	[1]	6,662	[1]
Other assets		14,353	(5,325)	[1]	5,808	[1]
Current liabilities		(15,680)	10,678	[1]	5,646	[1]
Other liabilities		(14,769)	64	[1]	1,518	[1]
Other, net		1,903	(833)	[1]	1,589	[1]
Net cash provided by operating activities		167,892	43,995	[1]	157,778	[1]
Investing activities:
Proceeds from sale of assets, net of cash transferred		18,703	31,564	[1]	10,304	[1]
Acquisition of businesses, net of cash acquired		(167,677)	(18,396)	[1]	(20,533)	[1]
Capital expenditures		(38,481)	(46,131)	[1]	(37,497)	[1]
Insurance proceeds - capital related		1,968	0	[1]	0	[1]
Investment in unconsolidated affiliates		(1,609)	(3,317)	[1]	0	[1]
Net cash used in investing activities		(187,096)	(36,280)	[1]	(47,726)	[1]
Financing activities:
Dividends paid to stockholders of Mueller Industries, Inc.		(22,705)	(196,944)	[1]	(21,224)	[1]
Dividends paid to noncontrolling interests		(592)	(2,909)	[1]	(3,765)	[1]
Issuance of long-term debt		204,233	71,475	[1]	3,500	[1]
Repayments of long-term debt		(172,002)	(111,224)	[1]	(1,074)	[1]
(Repayment) issuance of debt by consolidated joint ventures, net		(2,915)	(3,369)	[1]	2,265	[1]
Repurchase of common stock		(33,562)	0	[1]	0	[1]
Net cash used to settle stock-based awards		(726)	(1,595)	[1]	(1,306)	[1]
Debt issuance costs		0	0	[1]	(957)	[1]
Net cash used in financing activities		(28,269)	(244,566)	[1]	(22,561)	[1]
Effect of exchange rate changes on cash		(1,952)	2,945	[1]	(5,686)	[1]
(Decrease) increase in cash, cash equivalents, and restricted cash		(49,425)	(233,906)	[1]	81,805	[1]
Cash, cash equivalents, and restricted cash at the beginning of the year	[1]	126,563	360,469		278,664
Cash, cash equivalents, and restricted cash at the end of the year		$ 77,138	$ 126,563	[1]	$ 360,469	[1]
[1]	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.
[2]	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.

CONSOLIDATED STATEMENTS OF CHAN

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated other comprehensive loss:	Treasury Stock [Member]	Noncontrolling Interest [Member]
Balance at beginning of year (in shares) at Dec. 26, 2015			80,183				23,024
Balance at beginning of year at Dec. 26, 2015			$ 802	$ 271,158	$ 1,063,543	$ (54,990)	$ (453,228)	$ 32,417
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under incentive stock option plans (in shares)							(178)
Issuance of shares under incentive stock option plans				(419)			$ 3,499
Stock-based compensation expense				6,387
Issuance of restricted stock (in shares)							(191)
Issuance of restricted stock				(3,781)			$ 3,780
Net income attributable to Mueller Industries, Inc.	$ 99,727	[1]			99,727
Dividends paid or payable to stockholders of Mueller Industries, Inc.					(21,439)
Total other comprehensive (loss) income attributable to Mueller Industries, Inc.	(14,541)					(11,966)
Repurchase of common stock (in shares)							133
Repurchase of common stock							$ (4,389)
Sale of Mueller-Xingrong								0
Purchase of Jungwoo-Mueller								11,649
Dividends paid to noncontrolling interests	3,765	[2]						(3,765)
Net income attributable to noncontrolling interests	(27)	[1]						27
Foreign currency translation	(27,767)							(2,575)
Balance at end of year (in shares) at Dec. 31, 2016			80,183				22,788
Balance at end of year at Dec. 31, 2016			$ 802	273,345	1,141,831	(66,956)	$ (450,338)	37,753
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under incentive stock option plans (in shares)							(395)
Issuance of shares under incentive stock option plans				(2,118)			$ 7,828
Stock-based compensation expense				7,450
Issuance of restricted stock (in shares)							(208)
Issuance of restricted stock				(4,092)			$ 4,092
Net income attributable to Mueller Industries, Inc.	85,598	[1]			85,598
Dividends paid or payable to stockholders of Mueller Industries, Inc.					(483,926)
Total other comprehensive (loss) income attributable to Mueller Industries, Inc.	17,272					15,900
Repurchase of common stock (in shares)							188
Repurchase of common stock							$ (7,305)
Sale of Mueller-Xingrong								(23,712)
Dividends paid to noncontrolling interests	2,909	[2]						(2,909)
Net income attributable to noncontrolling interests	(1,413)	[1]						1,413
Foreign currency translation	13,174							1,372
Balance at end of year (in shares) at Dec. 30, 2017			80,183				22,373
Balance at end of year at Dec. 30, 2017	536,028		$ 802	274,585	743,503	(51,056)	$ (445,723)	13,917
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under incentive stock option plans (in shares)							(57)
Issuance of shares under incentive stock option plans				(278)			$ 1,136
Stock-based compensation expense				8,035
Issuance of restricted stock (in shares)							(273)
Issuance of restricted stock				(5,493)			$ 5,493
Net income attributable to Mueller Industries, Inc.	104,459				104,459
Dividends paid or payable to stockholders of Mueller Industries, Inc.					(23,009)
Reclassification of stranded effects of the Act					(556)	556
Other adjustments					340
Total other comprehensive (loss) income attributable to Mueller Industries, Inc.	(30,074)					(29,292)
Repurchase of common stock (in shares)							1,437
Repurchase of common stock							$ (35,146)
Sale of Mueller-Xingrong								0
Dividends paid to noncontrolling interests	592							(592)
Net income attributable to noncontrolling interests	(2,361)							2,361
Foreign currency translation	(16,876)							(782)
Balance at end of year (in shares) at Dec. 29, 2018			80,183				23,480
Balance at end of year at Dec. 29, 2018	$ 563,260		$ 802	$ 276,849	$ 824,737	$ (79,792)	$ (474,240)	$ 14,904
[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.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 29, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Nature of Operations The principal business of Mueller Industries, Inc. is the manufacture and sale of copper tube and fittings; line sets; brass and copper alloy rod, bar, and shapes; aluminum and brass forgings; aluminum impact extrusions; PEX plastic tube and fittings; refrigeration valves and fittings; compressed gas valves; fabricated tubular products; pressure vessels; steel nipples; and insulated flexible duct systems. The Company also resells brass and plastic plumbing valves, plastic fittings, malleable iron fittings, faucets, and plumbing specialty products. The Company markets its products to the HVAC, plumbing, refrigeration, hardware, and other industries. Mueller’s operations are located throughout the United States and in Canada, Mexico, Great Britain, South Korea, the Middle East, and China. Fiscal Years The Company’s fiscal year ends on the last Saturday of December, and consisted of 52 weeks in 2018 and 2017 , compared to 53 weeks in 2016 . These dates were December 29, 2018 , December 30, 2017 , and December 31, 2016 . Basis of Presentation The Consolidated Financial Statements include the accounts of Mueller Industries, Inc. and its majority-owned subsidiaries. The noncontrolling interests represent separate private ownership interests of 40 percent of Jungwoo Metal Ind. Co., LTD (Jungwoo-Mueller) and 49.5 percent of Jiangsu Mueller-Xingrong Copper Industries Limited (Mueller-Xingrong), which the Company sold during 2017 . See “ Note 2 – Acquisitions and Dispositions ” for additional information. Revenue Recognition Given the nature of the Company’s business and product offerings, sales transactions with customers are generally comprised of a single performance obligation that involves delivery of the products identified in the contracts with customers. Performance obligations are generally satisfied at the point in time of shipment and payment is generally due within sixty days. Variable consideration is estimated for future rebates on certain product lines and product returns. The Company records variable consideration as an adjustment to the transaction price in the period it is incurred. Since variable consideration is settled within a short period of time, the time value of money is not significant. The cost of shipping product to customers is expensed as incurred as a component of cost of goods sold. Acquisitions Accounting for acquisitions requires the Company to recognize separately from goodwill the assets acquired and liabilities assumed at their acquisition date fair values. Goodwill is measured as the excess of the purchase price over the net amount allocated to the identifiable assets acquired and liabilities assumed. While management uses its best estimates and assumptions to accurately value assets acquired and liabilities assumed at the acquisition date, the estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, which may be up to one year from the acquisition date, the Company may record adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. The operating results generated by the acquired businesses are included in the Consolidated Statements of Income from their respective dates of acquisition. Acquisition related costs are expensed as incurred. See “ Note 2 – Acquisitions and Dispositions ” for additional information. Cash Equivalents and Restricted Cash Temporary investments with original maturities of three months or less are considered to be cash equivalents. These investments are stated at cost. At December 29, 2018 and December 30, 2017 , temporary investments consisted of money market mutual funds, commercial paper, bank repurchase agreements, and U.S. and foreign government securities totaling approximately $0.6 million each year. Included in other current assets was restricted cash of $4.4 million and $6.2 million at December 29, 2018 and December 30, 2017 , respectively. These amounts represent required deposits into brokerage accounts that facilitate the Company’s hedging activities as well as imprest funds for the Company’s self-insured workers’ compensation program. Allowance for Doubtful Accounts The Company provides an allowance for receivables that may not be fully collected. In circumstances where the Company is aware of a customer’s inability to meet their financial obligations (e.g., bankruptcy filings or substantial credit rating downgrades), it records an allowance for doubtful accounts against amounts due to reduce the net recognized receivable to the amount it believes most likely will be collected. For all other customers, the Company recognizes an allowance for doubtful accounts based on its historical collection experience. If circumstances change (e.g., greater than expected defaults or an unexpected material change in a major customer’s ability to meet their financial obligations), the Company could change its estimate of the recoverability of amounts due by a material amount. Inventories The Company’s inventories are valued at the lower-of-cost-or-market. The material component of its U.S. copper tube and copper fittings inventories is valued on a LIFO basis and the non-material components of U.S. copper tube and copper fittings inventories are valued on a FIFO basis. The material component of its U.K. and Canadian copper tube inventories are valued on a FIFO basis. The material component of its brass rod and forgings inventories are valued on a FIFO basis. Certain inventories purchased for resale are valued on an average cost basis. Elements of cost in finished goods inventory in addition to the cost of material include depreciation, amortization, utilities, maintenance, production wages, and transportation costs. The market price of copper cathode and scrap is subject to volatility. During periods when open market prices decline below net book value, the Company may need to provide an allowance to reduce the carrying value of its inventory. In addition, certain items in inventory may be considered obsolete and, as such, the Company may establish an allowance to reduce the carrying value of those items to their net realizable value. Changes in these estimates related to the value of inventory, if any, may result in a materially adverse impact on the Company’s reported financial position or results of operations. The Company recognizes the impact of any changes in estimates, assumptions, and judgments in income in the period in which it is determined. See “ Note 4 – Inventories ” for additional information. Property, Plant, and Equipment Property, plant, and equipment is stated at cost less accumulated depreciation. Expenditures for major additions and improvements are capitalized, while minor replacements, maintenance, and repairs are charged to expense as incurred. Depreciation of buildings, machinery, and equipment is provided on the straight-line method over the estimated useful lives ranging from 20 to 40 years for buildings and five to 20 years for machinery and equipment. Leasehold improvements are amortized over the lesser of their useful life or the remaining lease term. The Company continually evaluates these assets to determine whether events or changes in circumstances have occurred that may warrant revision of the estimated useful life or whether the remaining balance should be evaluated for possible impairment. See “ Note 7 – Property, Plant, and Equipment, Net ” for additional information. Goodwill Goodwill is recognized for the excess of the purchase price over the fair value of tangible and identifiable intangible net assets of businesses acquired. Several factors give rise to goodwill in business acquisitions, such as the expected benefit from synergies of the combination and the existing workforce of the acquired business. Goodwill is evaluated annually for possible impairment as of the first day of the fourth quarter unless circumstances indicate the need to accelerate the timing of the evaluation. In the evaluation of goodwill impairment, management performs a qualitative assessment to determine if it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the qualitative assessment is not conclusive, management compares the fair value of a reporting unit with its carrying amount and will recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, not to exceed the total amount of goodwill allocated to the reporting unit. Fair value for the Company’s reporting units is determined using a combination of the income and market approaches (level 3 within the fair value hierarchy), incorporating market participant considerations and management’s assumptions on revenue growth rates, operating margins, discount rates and expected capital expenditures. The market approach measures the fair value of a business through the analysis of publicly traded companies or recent sales of similar businesses. The income approach uses a discounted cash flow model to estimate the fair value of reporting units based on expected cash flows (adjusted for capital investment required to support operations) and a terminal value. This cash flow stream is discounted to its present value to arrive at a fair value for each reporting unit. Future earnings are estimated using the Company’s most recent annual projections, applying a growth rate to future periods. Those projections are directly impacted by the condition of the markets in which the Company’s businesses participate. The discount rate selected for the reporting units is generally based on rates of return available for comparable companies at the date of valuation. Fair value determinations may include both internal and third-party valuations. See “ Note 8 – Goodwill and Other Intangible Assets ” for additional information. Investments in Unconsolidated Affiliates The Company owns a 50 percent interest in an unconsolidated affiliate that acquired Tecumseh Products Company (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 Consolidated Statements of Income. The Company’s proportionate share of the investees’ other comprehensive income (loss), net of income taxes, is recorded in the Consolidated Statements of Comprehensive Income and 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 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 Company also owns a 40 percent interest in Mueller Middle East BSC. The investments in unconsolidated affiliates are assessed periodically for impairment and written down when the carrying amount is not considered fully recoverable. See “ Note 9 – Investments in Unconsolidated Affiliates ” for additional information. Self-Insurance Accruals The Company is primarily self-insured for workers’ compensation claims and benefits paid under certain employee health care programs. Accruals are primarily based on estimated undiscounted cost of claims, which includes incurred but not reported claims, and are classified as accrued wages and other employee costs. Pension and Other Postretirement Benefit Plans The Company sponsors several qualified and nonqualified pension and other postretirement benefit plans in the U.S. and certain foreign locations. The Company recognizes the overfunded or underfunded status of the plans as an asset or liability in the Consolidated Balance Sheets with changes in the funded status recorded through comprehensive income in the year in which those changes occur. The obligations for these plans are actuarially determined and affected by assumptions, including discount rates, expected long-term return on plan assets for defined benefit pension plans, and certain employee-related factors, such as retirement age and mortality. The Company evaluates its assumptions periodically and makes adjustments as necessary. The expected return on plan assets is determined using the market value of plan assets. Differences between assumed and actual returns are amortized to the market value of assets on a straight-line basis over the average remaining service period of the plan participants using the corridor approach. The corridor approach defers all actuarial gains and losses resulting from variances between actual results and actuarial assumptions. These unrecognized gains and losses are amortized when the net gains and losses exceed 10 percent of the greater of the market value of the plan assets or the projected benefit obligation. The amount in excess of the corridor is amortized over the average remaining service period of the plan participants. For 2018 , the average remaining service period for the pension plans was nine years . See “ Note 11 – Benefit Plans ” for additional information. Environmental Reserves and Environmental Expenses The Company recognizes an environmental liability when it is probable the liability exists and the amount is reasonably estimable. The Company estimates the duration and extent of its remediation obligations based upon reports of outside consultants, internal and third party estimates and analyses of cleanup costs and ongoing monitoring costs, communications with regulatory agencies, and changes in environmental law. If the Company were to determine that its estimates of the duration or extent of its environmental obligations were no longer accurate, it would adjust environmental liabilities accordingly in the period that such determination is made. Estimated future expenditures for environmental remediation are not discounted to their present value. Environmental expenses that relate to ongoing operations are included as a component of cost of goods sold. Environmental expenses related to non-operating properties are presented below operating income in the Consolidated Statements of Income. See “ Note 12 – Commitments and Contingencies ” for additional information. Earnings Per Share Basic earnings per share is computed based on the weighted average number of common shares outstanding. Diluted earnings per share reflects the increase in weighted average common shares outstanding that would result from the assumed exercise of outstanding stock options and vesting of restricted stock awards calculated using the treasury stock method. Approximately 54 thousand and 20 thousand stock-based awards were excluded from the computation of diluted earnings per share for the years ended December 29, 2018 and December 30, 2017 , respectively, because they were antidilutive. Income Taxes Deferred income tax assets and liabilities are recognized when differences arise between the treatment of certain items for financial statement and tax purposes. Realization of certain components of deferred tax assets is dependent upon the occurrence of future events. The Company records valuation allowances to reduce its deferred tax assets to the amount it believes is more likely than not to be realized. These valuation allowances can be impacted by changes in tax laws, changes to statutory tax rates, and future taxable income levels and are based on the Company’s judgment, estimates, and assumptions regarding those future events. In the event the Company was to determine that it would not be able to realize all or a portion of the net deferred tax assets in the future, it would increase the valuation allowance through a charge to income tax expense in the period that such determination is made. Conversely, if it was to determine that it would be able to realize its deferred tax assets in the future, in excess of the net carrying amounts, the Company would decrease the recorded valuation allowance through a decrease to income tax expense in the period that such determination is made. The Company provides for uncertain tax positions and the related interest and penalties, if any, based upon management’s assessment of whether a tax benefit is more likely than not to be sustained upon examination by tax authorities. Tax benefits for uncertain tax positions that are recognized in the financial statements are measured as the largest amount of benefit, determined on a cumulative probability basis, that is more likely than not to be realized upon ultimate settlement. To the extent the Company prevails in matters for which a liability for an uncertain tax position is established or is required to pay amounts in excess of the liability, the Company’s effective tax rate in a given financial statement period may be affected. These estimates are highly subjective and could be affected by changes in business conditions and other factors. Changes in any of these factors could have a material impact on future income tax expense. See “ Note 13 – Income Taxes ” for additional information. Taxes Collected from Customers and Remitted to Governmental Authorities Taxes assessed by a governmental authority that are directly imposed on a revenue producing transaction between the Company and its customers, primarily value added taxes in foreign jurisdictions, are accounted for on a net (excluded from revenues and costs) basis. Stock-Based Compensation The Company has in effect stock incentive plans under which stock-based awards have been granted to certain employees and members of its Board of Directors. Stock-based compensation expense is recognized in the Consolidated Statements of Income as a component of selling, general, and administrative expense based on the grant date fair value of the awards. See “ Note 15 – Stock-Based Compensation ” for additional information. Concentrations of Credit and Market Risk Concentrations of credit risk with respect to accounts receivable are limited due to the large number of customers comprising the Company’s customer base, and their dispersion across different geographic areas and different industries, including HVAC, plumbing, refrigeration, hardware, automotive, OEMs, and others. The Company minimizes its exposure to base metal price fluctuations through various strategies. Generally, it prices an equivalent amount of copper raw material, under flexible pricing arrangements it maintains with its suppliers, at the time it determines the selling price of finished products to its customers. 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 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 (i) a forecasted transaction or the variability of cash flow to be paid (cash flow hedge) or (ii) the fair value of a recognized asset or liability (fair value 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 accumulated other comprehensive income (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 a derivative that is qualified, designated, and highly effective as a fair value hedge, along with the gain or loss on the hedged recognized asset or liability that is attributable to the hedged risk, are recorded in current earnings. Changes in the fair value of undesignated derivative instruments executed as economic hedges and the ineffective portion of designated derivatives 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 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 flow 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. The Company primarily executes derivative contracts with major financial institutions. These counterparties expose the Company to credit risk in the event of non-performance. The amount of such exposure is limited to the fair value of the contract plus the unpaid portion of amounts due to the Company pursuant to terms of the derivative instruments, if any. If a downgrade in the credit rating of these counterparties occurs, management believes that this exposure is mitigated by provisions in the derivative arrangements which allow for the legal right of offset of any amounts due to the Company from the counterparties with any amounts payable to the counterparties by the Company. As a result, management considers the risk of loss from counterparty default to be minimal. See “ Note 6 – Derivative Instruments and Hedging Activities ” for additional information. Fair Value of Financial Instruments The carrying amounts for cash and cash equivalents, accounts receivable, and accounts payable approximate fair value due to the short-term maturity of these instruments. The fair value of long-term debt at December 29, 2018 approximates the carrying value on that date. The estimated fair values were determined based on quoted market prices and the current rates offered for debt with similar terms and maturities. The fair value of long-term debt is classified as level 2 within the fair value hierarchy. This classification is defined as a fair value determined using market-based inputs other than quoted prices that are observable for the liability, either directly or indirectly. Foreign Currency Translation For foreign subsidiaries for which the functional currency is not the U.S. dollar, balance sheet accounts are translated at exchange rates in effect at the end of the year and income statement accounts are translated at average exchange rates for the year. Translation gains and losses are included in equity as a component of AOCI. Transaction gains and losses that arise from exchange rate fluctuations on transactions denominated in a currency other than the functional currency are recognized in selling, general, and administrative expense in the Consolidated Statements of Income. Included in the Consolidated Statements of Income were net transaction losses of $1.0 million in 2018 , losses of $0.4 million in 2017 , and gains of $0.4 million in 2016 . Use of and Changes in Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States (U.S. GAAP) requires management to make estimates, assumptions, and judgments that affect the amounts reported in the financial statements and accompanying notes. Management makes its best estimate of the ultimate outcome for these items based on historical trends and other information available when the financial statements are prepared. Changes in estimates are recognized in accordance with the accounting rules for the estimate, which is typically in the period when new information becomes available to management. Areas where the nature of the estimate makes it reasonably possible that actual results could materially differ from amounts estimated include but are not limited to: pension and other postretirement benefit plan obligations, tax liabilities, loss contingencies, litigation claims, environmental reserves, and impairment assessments of long-lived assets (including goodwill). Recently Adopted Accounting Standard In February 2018, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . The ASU permits entities to reclassify tax effects stranded in AOCI as a result of tax reform to retained earnings. The guidance is effective for the Company in interim and annual periods beginning in 2019. Early adoption is permitted and can be applied retrospectively or in the period of adoption. The Company early adopted the ASU during the first quarter of 2018, which resulted in a net reclassification of $556 thousand from AOCI to retained earnings during the quarter. In March 2017, the FASB issued ASU No. 2017-07, Compensation - Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . The ASU requires employers that sponsor defined benefit pension and/or other postretirement benefit plans to present the service cost component of net periodic benefit cost in the same income statement line item(s) as other employee compensation costs arising from services rendered during the period and other components of net periodic benefits cost separately from the line item(s) that includes the service cost and outside of any subtotal of operating income. The Company adopted the ASU during the first quarter of 2018 using a retrospective approach for each period presented, and elected to use the practical expedient that allows the Company to use the amounts previously presented in its Benefit Plans disclosure as the estimation basis for applying the retrospective presentation requirements. Prior to the adoption of the ASU, net periodic benefit cost (income) was reported within selling, general, and administrative expense in the Consolidated Statements of Income. The prior periods have been revised to conform to the current period presentation, resulting in the reclassification net periodic benefit income of $1.2 million and net periodic benefit cost of $1.7 million from operating income to other income, net for the years ended 2017 and 2016 , respectively. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business . The ASU provides guidance to assist entities in evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The updated guidance requires prospective adoption. Early adoption is permitted. The Company early adopted the ASU during the first quarter of 2018 and the adoption had no impact on its Consolidated Financial Statements. In December 2016, the FASB issued ASU No. 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers . The ASU provides correction or improvement to the guidance previously issued in Accounting Standards Codification (ASC) 606, Revenue from Contracts with Customers . Under the ASU, an entity will recognize revenue to depict the transfer of promised goods or services to customers at an amount that reflects the consideration that it expects to receive in exchange for the goods or services. It also requires more detailed disclosures to enable users of financial statements to understand the nature, amount, timing and uncertainty of revenue and cash flows arising from contracts with customers. The ASU requires revenue to be recognized over time (i.e., throughout the production process) rather than at a point in time (generally upon shipment to the customer) if performance does not create an asset with an alternative use to the entity and the entity has an enforceable right to payment for performance completed to date. The Company adopted the ASU during the first quarter of 2018 using the modified retrospective method for all contracts with customers. The adoption did not result in a significant impact on opening retained earnings. Revenues for prior periods have not been adjusted and continue to be reported under Revenue Recognition (Topic 605) . No significant judgments were made in the application of the guidance in ASC 606 and there were no material contract assets, contract liabilities, or deferred contract costs as of December 29, 2018 . The Company also evaluated specific contract terms, primarily within the Industrial Metals and Climate segments, related to the production of customized products and payment rights and determined that there are no significant changes to the timing or nature of revenue recognition under the ASU. As part of the overall evaluation of the standard, the Company has assessed and implemented necessary changes to its accounting policies, practices, and internal controls over financial reporting to support the standard. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash . The ASU requires entities to report the changes in the total of cash, cash equivalents, restricted cash, and restricted cash equivalents in the statement of cash flows. As a result, entities will no longer present transfers between cash and cash equivalents and restricted cash and restricted cash equivalents in the statement of cash flows. The Company adopted the ASU during the first quarter of 2018 using a retrospective approach for each period presented. Prior to the adoption of the ASU, the Company presented the change in restricted cash balances separately as a cash flow from investing activity. Upon adoption, the Company included restricted cash in each of the balances of the cash, cash equivalents, and restricted cash at the beginning and end of periods in the Consolidated Statements of Cash Flows. The prior periods have been revised to conform to the current period presentation, and as a result, net cash flows for the years ended 2017 and 2016 increased by $6.3 million and $9.2 million , respectively. A reconciliation of cash, cash equivalents, and restricted cash for the periods presented is as follows: (In thousands) December 29, December 30, Cash & cash equivalents $ 72,616 $ 120,269 Restricted cash included within other current assets 4,414 6,189 Restricted cash included within other assets 108 105 Total cash, cash equivalents, and restricted cash $ 77,138 $ 126,563 In October 2016, the FASB issued ASU No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory . The ASU requires companies to account for the income tax effects of intercompany transfers of assets other than inventory when the transfer occurs. Companies will still be required to defer the income tax effects of intercompany inventory transactions in an exception to the income tax accounting guidance. The Company adopted the ASU during the first quarter of 2018 and the adoption had no impact on its Consolidated Financial Statements. Recently Issued Accounting Standards In August 2018, the FASB issued ASU No. 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20): Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans . For employers that sponsor defined benefit pension and/or other postretirement benefit plans, the ASU eliminates requirements for certain disclosures tha

Acquisitions and Dispositions

Acquisitions and Dispositions	12 Months Ended
	Dec. 29, 2018
Business Combinations [Abstract]
Acquisitions and Dispositions	Acquisitions and Dispositions 2018 Acquisitions ATCO On July 2, 2018, the Company entered into a stock purchase agreement pursuant to which the Company acquired all of the outstanding capital stock of ATCO Rubber Products, Inc. (ATCO) for approximately $156.7 million , net of the estimated working capital adjustment. The total purchase price consisted of $151.4 million in cash at closing and a contingent consideration arrangement which requires the Company to pay the former owner up to $12.0 million based on EBITDA growth of the acquired business. ATCO is an industry leader in the manufacturing and distribution of insulated HVAC flexible duct systems and will support the Company’s strategy to grow its Climate Products businesses to become a more valuable resource to its HVAC customers. The acquired business is reported in the Company’s Climate segment. For the year ended December 29, 2018 , the Company’s total net sales included $90.0 million of revenue recognized by ATCO from the date of acquisition. ATCO had revenues of approximately $166.0 million in its fiscal year ending December 31, 2017 (unaudited). The following table presents condensed pro forma consolidated results of operations as if the ATCO acquisition has occurred at the beginning of 2017. The pro forma information does not purport to be indicative of the results that would have been obtained if the operations had actually been combined during the periods presented, and is not necessarily indicative of operating results to be expected in future periods. The most significant pro forma adjustments to the historical results of operations relate to the application of purchase accounting and the financing structure. For the Year Ended (In thousands, except per share data) 2018 2017 Net sales $ 2,595,454 $ 2,431,972 Net income 111,482 90,270 Basic earnings per share $ 1.96 $ 1.59 Diluted earnings per share 1.95 1.57 Die-Mold On March 31, 2018, the Company entered into a share purchase agreement pursuant to which the Company acquired all of the outstanding shares of Die-Mold Tool Limited (Die-Mold) for approximately $13.6 million , net of working capital adjustments. The total purchase price consisted of $12.4 million in cash at closing and a contingent consideration arrangement which requires the Company to pay the former owner up to $2.3 million based on EBITDA growth of the acquired business. Die-Mold, based out of Ontario, Canada, is a manufacturer of plastic PEX and other plumbing-related fittings and an integrated designer and manufacturer of plastic injection tooling. The business complements the Company’s existing businesses within the Piping Systems segment. 2017 Acquisition Heatlink Group On May 31, 2017, the Company entered into a share purchase agreement pursuant to which the Company acquired all of the outstanding shares of Pexcor Manufacturing Company Inc. and Heatlink Group Inc. (collectively, Heatlink Group) for approximately $17.2 million , net of working capital adjustments. The total purchase price consisted of $16.3 million in cash at closing and a contingent consideration arrangement which requires the Company to pay the former owners up to $2.2 million based on EBITDA growth of the acquired business. Heatlink Group, based out of Calgary, Alberta, Canada, produces and sells a complete line of products for PEX plumbing and radiant systems. The business complements the Company’s existing businesses within the Piping Systems segment. 2016 Acquisition Jungwoo-Mueller On April 26, 2016, the Company entered into an agreement providing for the purchase of a 60 percent equity interest in Jungwoo-Mueller for approximately $20.5 million in cash. Jungwoo-Mueller, which manufactures copper-based pipe joining products, is headquartered in Seoul, South Korea and serves markets worldwide. This business complements the Company’s existing copper fittings businesses in the Piping Systems segment and is reported in the Company’s Consolidated Financial Statements one month in arrears. Purchase Price Allocations These acquisitions were accounted for using the acquisition method of accounting whereby the total purchase price was allocated to tangible and intangible assets acquired and liabilities assumed based on respective fair values. The following table summarizes the allocation of the purchase price to acquire these businesses, which were financed by available cash balances, as well as the assets acquired and liabilities assumed at the respective acquisition dates. The purchase price allocation for ATCO is provisional as of December 29, 2018 and subject to change upon completion of the final valuation of the long-lived assets, contingent consideration, and final working capital adjustment during the measurement period. During 2018 , the valuation of the Heatlink Group acquisition was finalized. Changes to the purchase price allocation from the amounts presented in the Company’s 2017 Annual Report on Form 10-K included the valuation of the contingent consideration of $0.9 million and the recognition of a deferred tax liability of $1.9 million that resulted from a basis difference in the long-lived assets acquired. These changes resulted in an increase to goodwill. (in thousands) ATCO Die-Mold Heatlink Group Jungwoo-Mueller Total consideration $ 156,704 $ 13,629 $ 17,164 $ 20,533 Allocated to: Accounts receivable 21,829 1,684 2,809 5,551 Inventories 31,666 1,833 4,648 17,616 Other current assets 1,051 267 508 1,437 Property, plant, and equipment 83,080 3,278 2,024 24,191 Goodwill 17,770 (1) 2,241 6,879 223 Intangible assets 21,430 5,209 6,413 756 Other assets 224 — — 277 Total assets acquired 177,050 14,512 23,281 50,051 Accounts payable 8,093 710 3,633 7,252 Other current liabilities 10,187 173 593 577 Long-term debt 2,066 — — 8,659 Pension and other postretirement liabilities — — — 799 Other noncurrent liabilities — — 1,891 582 Total liabilities assumed 20,346 883 6,117 17,869 Noncontrolling interest — — — 11,649 Net assets acquired $ 156,704 $ 13,629 $ 17,164 $ 20,533 (1) Tax-deductible goodwill The fair value of the noncontrolling interest at Jungwoo-Mueller was determined based on the proportionate share of consideration transferred and adjusted for lack of control and marketability based on the average of the classic put option model and the Finnerty Formula. The following details the total intangible assets identified in the allocation of the purchase price at the respective acquisition dates: (in thousands) Estimated Useful Life ATCO Die-Mold Heatlink Group Jungwoo-Mueller Intangible asset type: Customer relationships 20 years $ 6,200 $ 3,077 $ 4,265 $ — Non-compete agreements 3-5 years — 70 74 — Patents and technology 10-15 years 8,950 1,512 1,466 756 Trade names, licenses, and other 5-10 years 3,960 550 608 — Supply contracts 5 years 2,320 — — — Total intangible assets $ 21,430 $ 5,209 $ 6,413 $ 756 2017 Disposition Mueller-Xingrong On June 21, 2017, the Company entered into a definitive equity transfer agreement with Jiangsu Xingrong Hi-Tech Co. Ltd. and Jiangsu Baiyang Industries Co. Ltd. (Baiyang), together, the minority partners in Mueller-Xingrong (the Company’s Chinese joint venture), pursuant to which the Company sold its 50.5 percent equity interest in Mueller-Xingrong to Baiyang for approximately $18.3 million . Mueller-Xingrong manufactured engineered copper tube primarily for air-conditioning applications in China and was included in the Piping Systems segment. Mueller-Xingrong reported net sales of $67.3 million and net losses of $9 thousand in 2017 , compared to net sales of $121.5 million and net income of $62 thousand in 2016 . The carrying value of the assets disposed totaled $56.8 million , consisting primarily of accounts receivable, inventories, and long-lived assets. The carrying value of the liabilities disposed (consisting primarily of current debt and accounts payable), noncontrolling interest, and amounts recognized in AOCI totaled $36.2 million . Since the disposal constituted a complete liquidation of the Company’s investment in a foreign entity, the Company removed from AOCI and recognized a cumulative translation gain of $3.8 million . As a result of the disposal, the Company recognized a net gain on the sale of this business of $1.5 million in the Consolidated Financial Statements.

Segment Information

Segment Information	12 Months Ended
	Dec. 29, 2018
Segment Reporting [Abstract]
Segment Information	Segment Information The Company’s reportable segments are Piping Systems, Industrial Metals, and Climate. Each of the 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, and Jungwoo-Mueller (the Company’s South Korean joint venture). The Domestic Piping Systems Group manufactures 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 manufacture 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 OEMs. During 2018 , the segment recognized a gain of $1.4 million on the sale of real property and a gain of $0.7 million on the sale of manufacturing equipment. During 2017 , the segment recognized a gain of $1.5 million on the sale of the Company’s interest in Mueller-Xingrong and impairment charges of $1.5 million on certain copper fittings manufacturing equipment. During 2016 , the segment recognized impairment charges of $6.1 million on fixed assets used for product development. 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. During 2018 , the segment recognized an insurance recovery gain of $3.7 million related to the losses incurred due to the 2017 fire at the brass rod mill in Port Huron, Michigan and a gain of $1.3 million on the sale of real property. During 2016 , the segment recognized impairment charges of $0.7 million on fixed assets related to the rationalization of Sherwood. Climate Climate is composed of the following operating segments: Refrigeration Products, Fabricated Tube Products, Westermeyer, Turbotec, and ATCO. These domestic businesses manufacture and fabricate valves, assemblies, high pressure components, coaxial heat exchangers, and insulated HVAC flexible duct systems primarily for the heating, ventilation, air-conditioning, and refrigeration markets in the U.S. Performance of segments is generally evaluated by their operating income. Summarized product line, geographic, and segment information is shown in the following tables. Geographic sales data indicates the location from which products are shipped. Unallocated expenses include general corporate expenses, plus certain charges or credits not included in segment activity. During 2018 , 2017 , and 2016 , no single customer exceeded 10 percent of worldwide sales. The following tables represent a disaggregation of revenue from contracts with customers, along with the reportable segment for each category: For the Year Ended December 29, 2018 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 1,352,875 $ — $ — $ 1,352,875 Brass rod and forgings — 501,472 — 501,472 OEM components, tube & assemblies 29,578 53,581 139,113 222,272 Valves and plumbing specialties 263,180 — — 263,180 Other — 96,008 89,956 185,964 $ 1,645,633 $ 651,061 $ 229,069 $ 2,525,763 Intersegment sales (17,885 ) Net sales $ 2,507,878 For the Year Ended December 30, 2017 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 1,238,258 $ — $ — $ 1,238,258 Brass rod and forgings — 461,603 — 461,603 OEM components, tube & assemblies 94,383 51,707 131,448 277,538 Valves and plumbing specialties 232,309 — — 232,309 Other — 88,821 — 88,821 $ 1,564,950 $ 602,131 $ 131,448 $ 2,298,529 Intersegment sales (32,456 ) Net sales $ 2,266,073 Disaggregation of revenue from contracts with customers (continued): For the Year Ended December 31, 2016 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 1,045,031 $ — $ — $ 1,045,031 Brass rod and forgings — 369,363 — 369,363 OEM components, tube & assemblies 145,017 69,578 119,758 334,353 Valves and plumbing specialties 239,541 — — 239,541 Other — 82,119 — 82,119 $ 1,429,589 $ 521,060 $ 119,758 $ 2,070,407 Intersegment sales (14,785 ) Net sales $ 2,055,622 Summarized geographic information is as follows: (In thousands) 2018 2017 2016 Net sales: United States $ 1,820,857 $ 1,556,825 $ 1,400,893 United Kingdom 245,458 231,039 197,039 Canada 292,798 280,140 237,162 Asia 59,730 121,295 149,875 Mexico 89,035 76,774 70,653 $ 2,507,878 $ 2,266,073 $ 2,055,622 (In thousands) 2018 2017 2016 Long-lived assets: United States $ 295,735 $ 238,752 $ 223,099 United Kingdom 16,313 17,661 15,978 Canada 33,144 21,327 18,928 Asia 24,930 25,973 36,722 Mexico 511 608 504 $ 370,633 $ 304,321 $ 295,231 Summarized segment information is as follows: For the Year Ended December 29, 2018 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 1,645,633 $ 651,061 $ 229,069 $ (17,885 ) $ 2,507,878 Cost of goods sold 1,426,729 559,367 182,456 (18,152 ) 2,150,400 Depreciation and amortization 23,304 7,568 5,569 3,114 39,555 Selling, general, and administrative expense 74,864 13,501 16,926 43,597 148,888 (Gain) loss on sale of assets (2,093 ) (1,301 ) — 3,141 (253 ) Insurance recovery — (3,681 ) — — (3,681 ) Operating income 122,829 75,607 24,118 (49,585 ) 172,969 Interest expense (25,199 ) Environmental expense (1,320 ) Other income, net 3,967 Income before income taxes $ 150,417 For the Year Ended December 30, 2017 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 1,564,950 $ 602,131 $ 131,448 $ (32,456 ) $ 2,266,073 Cost of goods sold 1,369,161 506,973 98,851 (34,368 ) 1,940,617 Depreciation and amortization 21,777 7,516 2,513 2,138 33,944 Selling, general, and administrative expense 74,441 13,278 9,759 43,252 140,730 Gain on sale of assets (1,491 ) — — — (1,491 ) Impairment charges 1,466 — — — 1,466 Operating income 99,596 74,364 20,325 (43,478 ) 150,807 Interest expense (19,502 ) Environmental expense (7,284 ) Other income, net 2,951 Income before income taxes $ 126,972 Segment information (continued): For the Year Ended December 31, 2016 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 1,429,589 $ 521,060 $ 119,758 $ (14,785 ) $ 2,055,622 Cost of goods sold 1,228,949 420,905 89,927 (16,282 ) 1,723,499 Depreciation and amortization 22,421 8,162 2,437 2,113 35,133 Selling, general, and administrative expense 67,178 13,943 9,661 45,029 135,811 Impairment charges 6,115 663 — — 6,778 Operating income 104,926 77,387 17,733 (45,645 ) 154,401 Interest expense (7,387 ) Environmental expense (1,279 ) Other income, net 295 Income before income taxes $ 146,030 (In thousands) 2018 2017 2016 Expenditures for long-lived assets (including those resulting from business acquisitions): Piping Systems $ 31,362 $ 18,124 $ 56,286 Industrial Metals 8,066 5,322 3,302 Climate 85,471 2,191 2,045 General Corporate 37 22,518 55 $ 124,936 $ 48,155 $ 61,688 Segment assets: Piping Systems $ 818,303 $ 801,468 $ 826,663 Industrial Metals 173,725 212,638 160,478 Climate 246,851 73,458 66,968 General Corporate 130,670 232,609 393,367 $ 1,369,549 $ 1,320,173 $ 1,447,476

Inventories

Inventories	12 Months Ended
	Dec. 29, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories (In thousands) 2018 2017 Raw materials and supplies $ 89,641 $ 108,397 Work-in-process 58,643 46,158 Finished goods 188,506 180,143 Valuation reserves (6,995 ) (6,797 ) Inventories $ 329,795 $ 327,901 Inventories valued using the LIFO method totaled $18.8 million at December 29, 2018 and $26.5 million at December 30, 2017 . At December 29, 2018 and December 30, 2017 , the approximate FIFO cost of such inventories was $ 91.8 million and $ 111.0 million , respectively. Additionally, the Company values certain inventories purchased for resale on an average cost basis. The value of those inventories was $ 53.6 million at December 29, 2018 and $ 43.9 million at December 30, 2017 . At the end of 2018 and 2017 , the FIFO value of inventory consigned to others was $ 5.1 million and $ 4.4 million , respectively.

Consolidated Financial Statemen

Consolidated Financial Statement Details	12 Months Ended
	Dec. 29, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidated Financial Statement Details	Consolidated Financial Statement Details Other Current Liabilities Included in other current liabilities as of December 29, 2018 and December 30, 2017 were the following: (i) accrued discounts, allowances, and customer rebates of $ 48.6 million and $ 39.5 million , respectively, (ii) current taxes payable of $ 5.0 million and $ 9.2 million , respectively, (iii) accrued interest of $5.8 million and $5.9 million , respectively, and (iv) current environmental liabilities of $3.6 million and $4.3 million , respectively. Other Income, Net (In thousands) 2018 2017 2016 Net periodic benefit income (cost) $ 2,914 $ 1,150 $ (1,687 ) Interest income 624 684 1,185 Other 429 1,117 797 Other income, net $ 3,967 $ 2,951 $ 295

Derivative Instruments and Hedg

Derivative Instruments and Hedging Activities	12 Months Ended
	Dec. 29, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities	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. 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 December 29, 2018 , the Company held open futures contracts to purchase approximately $ 59.4 million of copper over the next 12 months related to fixed price sales orders. The fair value of those futures contracts was a $ 1.3 million net loss 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 December 29, 2018 , this amount was approximately $ 0.4 million of deferred net losses , net of tax. The Company may also enter into futures contracts to protect the value of inventory against market fluctuations. At December 29, 2018 , the Company held open futures contracts to sell approximately $ 3.1 million of copper over the next five months related to copper inventory. The fair value of those futures contracts was a $ 0.1 million net gain 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 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 2018 2017 Balance Sheet Location 2018 2017 Commodity contracts - gains Other current assets $ 88 $ 1,014 Other current liabilities $ 103 $ 55 Commodity contracts - losses Other current assets (1 ) (5 ) Other current liabilities (1,382 ) (3,210 ) Total derivatives (1) $ 87 $ 1,009 $ (1,279 ) $ (3,155 ) (1) Does not include the impact of cash collateral provided to counterparties . The following table summarizes the effects of derivative instruments on the Consolidated Statements of Income: (In thousands) Location 2018 2017 Fair value hedges: Gain (loss) on commodity contracts (qualifying) Cost of goods sold $ 391 $ (724 ) (Loss) gain on hedged item - inventory Cost of goods sold (385 ) 625 Undesignated derivatives: Gain (loss) on commodity contracts (nonqualifying) Cost of goods sold $ 4,227 $ (6,078 ) The following tables summarize amounts recognized in and reclassified from AOCI during the period: Year Ended December 29, 2018 (In thousands) Loss Recognized in AOCI (Effective Portion), Net of Tax Classification Gains (Losses) Gain Reclassified from AOCI (Effective Portion), Net of Tax Cash flow hedges: Commodity contracts $ (793 ) Cost of goods sold $ (371 ) Other (9 ) Other — Total $ (802 ) Total $ (371 ) Year Ended December 30, 2017 (In thousands) (Loss) Gain 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 $ (574 ) Cost of goods sold $ 990 Interest rate swap — Interest expense 546 Other 185 Other — Total $ (389 ) Total $ 1,536 The Company enters into futures and forward contracts that closely match the terms of the underlying transactions. As a result, the ineffective portion of the qualifying open hedge contracts through December 29, 2018 was not material to the Consolidated Statements of Income. 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 the 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 December 29, 2018 and December 30, 2017 , the Company had recorded restricted cash in other current assets of $ 3.6 million and $ 5.3 million , respectively, as collateral related to open derivative contracts under the master netting arrangements.

Property, Plant, and Equipment,

Property, Plant, and Equipment, Net	12 Months Ended
	Dec. 29, 2018
Property, Plant and Equipment [Abstract]
Property, Plant, and Equipment, Net	Property, Plant, and Equipment, Net (In thousands) 2018 2017 Land and land improvements $ 32,132 $ 18,740 Buildings 201,176 144,527 Machinery and equipment 635,173 649,667 Construction in progress 22,618 9,274 891,099 822,208 Less accumulated depreciation (520,466 ) (517,887 ) Property, plant, and equipment, net $ 370,633 $ 304,321 Depreciation expense for property, plant, and equipment was $35.1 million in 2018 , $30.8 million in 2017 , and $30.8 million in 2016 .

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 29, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill The changes in the carrying amount of goodwill by segment were as follows: (In thousands) Piping Systems Industrial Metals Climate Total Goodwill $ 160,128 $ 8,854 $ 4,416 $ 173,398 Accumulated impairment charges (40,552 ) (8,853 ) — (49,405 ) Balance at December 31, 2016: 119,576 1 4,416 123,993 Additions (1) 3,852 — — 3,852 Currency translation 2,448 — — 2,448 Balance at December 30, 2017: 125,876 1 4,416 130,293 Additions (2) 5,049 — 17,770 22,819 Currency translation (2,777 ) — — (2,777 ) Balance at December 29, 2018: Goodwill 168,700 8,854 22,186 199,740 Accumulated impairment charges (40,552 ) (8,853 ) — (49,405 ) Goodwill, net $ 128,148 $ 1 $ 22,186 $ 150,335 (1) Includes finalization of the purchase price allocation adjustment for Jungwoo-Mueller of $0.2 million . (2) Includes finalization of the purchase price allocation adjustment for Heatlink Group of $2.8 million . Reporting units with recorded goodwill include Domestic Piping Systems Group, B&K LLC, Great Lakes, Heatlink Group, Die-Mold, European Operations, Jungwoo-Mueller, Westermeyer, Turbotec, and ATCO . Several factors give rise to goodwill in the Company’s acquisitions, such as the expected benefit from synergies of the combination and the existing workforce of the acquired businesses. There were no impairment charges resulting from the 2018 , 2017 , or 2016 annual impairment tests as the estimated fair value of each of the reporting units exceeded its carrying value. Other Intangible Assets The carrying amount of intangible assets at December 29, 2018 was as follows: (In thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Customer relationships $ 43,104 $ (6,309 ) $ 36,795 Non-compete agreements 2,400 (1,582 ) 818 Patents and technology 17,879 (2,595 ) 15,284 Trade names and licenses 9,173 (2,188 ) 6,985 Other 2,526 (437 ) 2,089 Other intangible assets $ 75,082 $ (13,111 ) $ 61,971 The carrying amount of intangible assets at December 30, 2017 was as follows: (In thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Customer relationships $ 36,518 $ (4,644 ) $ 31,874 Non-compete agreements 2,834 (1,497 ) 1,337 Patents and technology 7,673 (1,868 ) 5,805 Trade names and licenses 4,977 (1,575 ) 3,402 Other 213 (623 ) (410 ) Other intangible assets $ 52,215 $ (10,207 ) $ 42,008 Amortization expense for intangible assets was $4.4 million in 2018 , $3.1 million in 2017 , and $4.3 million in 2016 . Future amortization expense is estimated as follows: (In thousands) Amount 2019 $ 5,242 2020 5,047 2021 4,773 2022 4,693 2023 4,297 Thereafter 37,919 Expected amortization expense $ 61,971

Investment in Unconsolidated Af

Investment in Unconsolidated Affiliates	12 Months Ended
	Dec. 29, 2018
Equity Method Investments and Joint Ventures [Abstract]
Investment in Unconsolidated Affiliates	Investments in Unconsolidated Affiliates Tecumseh The Company owns a 50 percent interest in an unconsolidated affiliate that acquired Tecumseh. The Company also owns a 50 percent interest in a second unconsolidated affiliate that provides financing to Tecumseh. Tecumseh is a global manufacturer of hermetically sealed compressors for residential and specialty air conditioning, household refrigerators and freezers, and commercial refrigeration applications, including air conditioning and refrigeration compressors, as well as condensing units, heat pumps, and complete refrigeration systems. 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) 2018 2017 Current assets $ 228,214 $ 246,127 Noncurrent assets 114,257 139,200 Current liabilities 175,371 174,710 Noncurrent liabilities 57,216 58,334 Net sales $ 509,517 $ 556,600 Gross profit 59,385 75,600 Net loss (20,049 ) (4,153 ) The Company’s loss from unconsolidated affiliates, net of foreign tax, for 2018 included net losses of $14.0 million and charges of $3.0 million related to certain labor claim contingencies, offset by a gain of $7.0 million related to a settlement with the Brazilian Federal Revenue Agency 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 $4.5 million of cash to date and is the technical and marketing lead with a 40 percent ownership in the joint venture. The Company’s loss from unconsolidated affiliates, net of foreign tax, for 2018 included net losses of $2.6 million for Mueller Middle East.

Debt

Debt	12 Months Ended
	Dec. 29, 2018
Debt Disclosure [Abstract]
Debt	Debt (In thousands) 2018 2017 Subordinated Debentures with interest at 6.00%, due 2027 $ 284,479 $ 284,536 Revolving Credit Facility with interest at 3.97%, due 2021 195,000 160,000 Jungwoo-Mueller credit facility with interest at 2.86%, due 2019 5,264 5,119 Jungwoo-Mueller credit facility with interest at 3.45%, due 2020 5,104 8,648 2001 Series IRB's with interest at 3.22%, due 2021 2,250 3,250 Other 5,458 4,694 497,555 466,247 Less debt issuance costs (857 ) (1,175 ) Less current portion of debt (7,101 ) (16,480 ) Long-term debt $ 489,597 $ 448,592 Subordinated Debentures On March 9, 2017, the Company distributed a special dividend of $3.00 in cash and $5.00 in principal amount of the Company’s 6% Subordinated Debentures (Debentures) due March 1, 2027 for each share of common stock outstanding. Interest on the Debentures is payable semiannually on September 1 and March 1. The Debentures are subordinated to all other funded debt of the Company and are callable, in whole or in part, at any time at the option of the Company, subject to declining call premiums during the first five years. The Debentures also grant each holder the right to require the Company to repurchase such holder’s Debentures in the event of a change in control at declining repurchase premiums during the first five years. The Debentures may be redeemed, subject to the conditions set forth above, at the following redemption price (expressed as a percentage of principal amount) plus any accrued but unpaid interest to, but excluding, the redemption date: If redeemed during the 12-month period beginning March 9: Year Redemption Price 2018 105% 2019 104 2020 103 2021 102 2022 and thereafter 100 Revolving Credit Facility The Company’s Credit Agreement provides for an unsecured $350.0 million revolving credit facility (Revolving Credit Facility) that matures on December 6, 2021 . Borrowings under the Revolving Credit Facility bear interest, at the Company’s option, at LIBOR or Base Rate as defined by the Credit Agreement, plus a variable premium. LIBOR advances may be based upon the one, three, or six-month LIBOR. The variable premium is based upon the Company’s debt to total capitalization ratio, and can range from 112.5 to 162.5 basis points for LIBOR based loans and 12.5 to 62.5 basis points for Base Rate loans. At December 29, 2018 , the premium was 162.5 basis points for LIBOR loans and 62.5 basis points for Base Rate loans. Additionally, a commitment fee is payable quarterly on the total commitment less any outstanding loans or issued letters of credit, and varies from 15.0 to 30.0 basis points based upon the Company’s debt to total capitalization ratio. Availability of funds under the Revolving Credit Facility is reduced by the amount of certain outstanding letters of credit, which are used to secure the Company’s payment of insurance deductibles and certain retiree health benefits, totaling approximately $8.5 million at December 29, 2018 . Terms of the letters of credit are generally renewable annually. Jungwoo-Mueller Jungwoo-Mueller has several secured revolving credit arrangements with a total borrowing capacity of KRW 28.8 billion (or approximately $25.3 million ). Borrowings are secured by the real property and equipment of Jungwoo-Mueller. Covenants contained in the Company’s financing obligations require, among other things, the maintenance of minimum levels of tangible net worth and the satisfaction of certain minimum financial ratios. At December 29, 2018 , the Company was in compliance with all debt covenants. Aggregate annual maturities of the Company’s debt are as follows: (In thousands) Amount 2019 $ 7,101 2020 6,831 2021 195,955 2022 618 2023 402 Thereafter 286,648 Long-term debt $ 497,555 Net interest expense consisted of the following: (In thousands) 2018 2017 2016 Interest expense $ 25,349 $ 19,716 $ 7,749 Capitalized interest (150 ) (214 ) (362 ) $ 25,199 $ 19,502 $ 7,387 Interest paid in 2018 , 2017 , and 2016 was $25.2 million , $13.8 million , and $7.1 million , respectively.

Benefit Plans

Benefit Plans	12 Months Ended
	Dec. 29, 2018
Retirement Benefits [Abstract]
Benefit Plans	Benefit Plans Pension and Other Postretirement Plans The Company sponsors several qualified and nonqualified pension plans and other postretirement benefit plans for certain employees. The following tables provide a reconciliation of the changes in the plans’ benefit obligations and the fair value of the plans’ assets for 2018 and 2017 , and a statement of the plans’ aggregate funded status: Pension Benefits Other Benefits (In thousands) 2018 2017 2018 2017 Change in benefit obligation: Obligation at beginning of year $ 186,766 $ 178,736 $ 16,407 $ 15,274 Service cost 88 128 235 235 Interest cost 5,745 6,344 447 599 Actuarial (gain) loss (10,637 ) 4,688 (1,185 ) 923 Benefit payments (10,368 ) (10,171 ) (892 ) (883 ) Settlement charge — — (171 ) (209 ) Foreign currency translation adjustment (4,855 ) 7,041 (459 ) 468 Obligation at end of year 166,739 186,766 14,382 16,407 Change in fair value of plan assets: Fair value of plan assets at beginning of year 186,336 169,140 — — Actual return on plan assets (8,282 ) 19,175 — — Employer contributions 999 2,271 892 883 Benefit payments (10,368 ) (10,171 ) (892 ) (883 ) Foreign currency translation adjustment (4,082 ) 5,921 — — Fair value of plan assets at end of year 164,603 186,336 — — Underfunded status at end of year $ (2,136 ) $ (430 ) $ (14,382 ) $ (16,407 ) The following represents amounts recognized in AOCI (before the effect of income taxes): Pension Benefits Other Benefits (In thousands) 2018 2017 2018 2017 Unrecognized net actuarial loss $ 39,101 $ 34,627 $ 170 $ 1,540 Unrecognized prior service credit — — (6,387 ) (7,289 ) The Company sponsors one pension plan in the U.K. which comprised 45 and 44 percent of the above benefit obligation at December 29, 2018 and December 30, 2017 , respectively, and 37 and 39 percent of the above plan assets at December 29, 2018 and December 30, 2017 , respectively. As of December 29, 2018 , $1.8 million of the actuarial net loss and $0.9 million of the prior service credit will, through amortization, be recognized as components of net periodic benefit cost in 2019 . The aggregate status of all overfunded plans is recognized as an asset and the aggregate status of all underfunded plans is recognized as a liability in the Consolidated Balance Sheets. The amounts recognized as a liability are classified as current or long-term on a plan-by-plan basis. Liabilities are classified as current to the extent the actuarial present value of benefits payable within the next 12 months exceeds the fair value of plan assets, with all remaining amounts classified as long-term. As of December 29, 2018 and December 30, 2017 , the total funded status of the plans recognized in the Consolidated Balance Sheets was as follows: Pension Benefits Other Benefits (In thousands) 2018 2017 2018 2017 Long-term asset $ 10,580 $ 9,894 $ — $ — Current liability — — (1,080 ) (1,070 ) Long-term liability (12,716 ) (10,324 ) (13,302 ) (15,337 ) Total underfunded status $ (2,136 ) $ (430 ) $ (14,382 ) $ (16,407 ) The components of net periodic benefit cost (income) are as follows: (In thousands) 2018 2017 2016 Pension benefits: Service cost $ 88 $ 128 $ 532 Interest cost 5,745 6,344 7,553 Expected return on plan assets (9,522 ) (9,374 ) (9,615 ) Amortization of net loss 1,151 2,206 2,898 Settlement charge — — 1,214 Net periodic benefit (income) cost $ (2,538 ) $ (696 ) $ 2,582 Other benefits: Service cost $ 235 $ 235 $ 232 Interest cost 447 599 594 Amortization of prior service credit (902 ) (901 ) (896 ) Amortization of net loss (gain) 92 (42 ) (60 ) Settlement charge 38 17 — Net periodic benefit income $ (90 ) $ (92 ) $ (130 ) 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. The weighted average assumptions used in the measurement of the Company’s benefit obligations are as follows: Pension Benefits Other Benefits 2018 2017 2018 2017 Discount rate 3.72 % 3.22 % 4.56 % 3.89 % Expected long-term return on plan assets 5.05 % 5.27 % N/A N/A Rate of compensation increases N/A N/A 5.00 % 5.00 % Rate of inflation 3.40 % 3.30 % N/A N/A The weighted average assumptions used in the measurement of the Company’s net periodic benefit cost are as follows: Pension Benefits Other Benefits 2018 2017 2016 2018 2017 2016 Discount rate 3.22 % 3.61 % 4.02 % 3.89 % 4.21 % 4.25 % Expected long-term return on plan assets 5.27 % 5.56 % 5.59 % N/A N/A N/A Rate of compensation increases N/A N/A N/A 5.00 % 5.00 % 5.00 % Rate of inflation 3.30 % 3.30 % 3.20 % N/A N/A N/A The Company’s Mexican postretirement plans use the rate of compensation increase in the benefit formulas. Past service in the U.K. pension plan will be adjusted for the effects of inflation. All other pension and postretirement plans use benefit formulas based on length of service. The annual assumed rate of increase in the per capita cost of covered benefits (i.e., health care cost trend rate) is assumed to range from 6.4 to 8.4 percent for 2019 , gradually decrease to 3.0 percent through 2036 , and remain at that level thereafter. The health care cost trend rate assumption does not have a significant effect on the amounts reported. Pension Assets The weighted average asset allocation of the Company’s pension fund assets are as follows: Pension Plan Assets Asset category 2018 2017 Fixed income securities (includes fixed income mutual funds) 54 % 48 % Equity securities (includes equity mutual funds) 35 46 Cash and equivalents (includes money market funds) 8 3 Alternative investments 3 3 Total 100 % 100 % At December 29, 2018 , the long-term target allocation, by asset category, of assets of the Company’s defined benefit pension plans was: (i) fixed income securities – at least 60 percent ; (ii) equity securities, including equity index funds – not more than 30 percent ; and (iii) alternative investments – not more than 5 percent . The pension plan obligations are long-term and, accordingly, the plan assets are invested for the long-term. Plan assets are monitored periodically. Based upon results, investment managers and/or asset classes are redeployed when considered necessary. None of the plans’ assets are expected to be returned to the Company during the next fiscal year. The assets of the plans do not include investments in securities issued by the Company. The estimated rates of return on plan assets are the expected future long-term rates of earnings on plan assets and are forward-looking assumptions that materially affect pension cost. Establishing the expected future rates of return on pension assets is a judgmental matter. The Company reviews the expected long-term rates of return on an annual basis and revises as appropriate. The expected long-term rate of return on plan assets was 5.05 percent for 2018 and 5.27 percent in 2017 . The Company’s investments for its pension plans are reported at fair value. The following methods and assumptions were used to estimate the fair value of the Company’s plan asset investments: Cash and money market funds – Valued at cost, which approximates fair value. Common stock – Valued at the closing price reported on the active market on which the individual securities are traded. Mutual funds – Valued at the net asset value of shares held by the plans at December 29, 2018 and December 30, 2017 , respectively, based upon quoted market prices. Limited partnerships – Limited partnerships include investments in various Cayman Island multi-strategy hedge funds. The plans’ investments in limited partnerships are valued at the estimated fair value of the class shares owned by the plans based upon the equity in the estimated fair value of those shares. The estimated fair values of the limited partnerships are determined by the investment managers. In determining fair value, the investment managers of the limited partnerships utilize the estimated net asset valuations of the underlying investment entities. The underlying investment entities value securities and other financial instruments on a mark-to-market or estimated fair value basis. The estimated fair value is determined by the investment managers based upon, among other things, the type of investments, purchase price, marketability, current financial condition, operating results, and other information. The estimated fair values of substantially all of the investments of the underlying investment entities, which may include securities for which prices are not readily available, are determined by the investment managers or management of the respective underlying investment entities and may not reflect amounts that could be realized upon immediate sale. Accordingly, the estimated fair values may differ significantly from the values that would have been used had a ready market existed for these investments. The following table sets forth by level, within the fair value hierarchy, the assets of the plans at fair value: Fair Value Measurements at December 29, 2018 (In thousands) Level 1 Level 2 Level 3 Total Cash and money market funds $ 12,984 $ — $ — $ 12,984 Mutual funds (1) — 146,591 — 146,591 Limited partnerships — — 5,028 5,028 Total $ 12,984 $ 146,591 $ 5,028 $ 164,603 Fair Value Measurements at December 30, 2017 (In thousands) Level 1 Level 2 Level 3 Total Cash and money market funds $ 5,364 $ — $ — $ 5,364 Common stock (2) 11,113 — — 11,113 Mutual funds (3) 8,412 156,442 — 164,854 Limited partnerships — — 5,005 5,005 Total $ 24,889 $ 156,442 $ 5,005 $ 186,336 (1) Approximately 61 percent of mutual funds are actively managed funds and approximately 39 percent of mutual funds are index funds. Additionally, five percent of the mutual funds’ assets are invested in U.S. equities, 35 percent in non-U.S. equities, 59 percent in U.S. fixed income securities, and one percent in non-U.S. fixed income securities. (2) Approximately 91 percent of common stock represents investments in U.S. companies primarily in the health care, utilities, financials, consumer staples, industrials, and information technology sectors. All investments in common stock are listed on U.S. stock exchanges. (3) Approximately 66 percent of mutual funds are actively managed funds and approximately 34 percent of mutual funds are index funds. Additionally, five percent of the mutual funds’ assets are invested in U.S. equities, 41 percent in non-U.S. equities, 52 percent in U.S. fixed income securities, and two percent in non-U.S. fixed income securities. The table below reflects the changes in the assets of the plan measured at fair value on a recurring basis using significant unobservable inputs (level 3 of fair value hierarchy) during the year ended December 29, 2018 : (In thousands) Limited Partnerships Balance, December 30, 2017 $ 5,005 Redemptions (108 ) Subscriptions 108 Net appreciation in fair value 23 Balance, December 29, 2018 $ 5,028 Contributions and Benefit Payments The Company expects to contribute approximately $0.1 million to its pension plans and $1.1 million to its other postretirement benefit plans in 2019 . The Company expects future benefits to be paid from the plans as follows: (In thousands) Pension Benefits Other Benefits 2019 $ 10,416 $ 1,102 2020 10,342 1,244 2021 10,283 1,061 2022 10,241 1,112 2023 10,196 1,226 2024-2028 49,820 5,821 Total $ 101,298 $ 11,566 Multiemployer Plan The Company contributes to the IAM National Pension Fund, National Pension Plan (IAM Plan), a multiemployer defined benefit plan. Participation in the IAM Plan was negotiated under the terms of two collective bargaining agreements in Port Huron, Michigan, the Local 218 IAM and Local 44 UAW that expire on May 5, 2019 and July 21, 2019 , respectively. The Employer Identification Number for this plan is 51-6031295. The risks of participating in multiemployer plans are different from single-employer plans in the following aspects: (i) assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers; (ii) if a participating employer stops contributing to the plan, the underfunded obligations of the plan may be borne by the remaining participating employers; (iii) if the Company chooses to stop participating in the plan, the Company may be required to pay the plan an amount based on the underfunded status of the plan, referred to as a withdrawal liability. The Company makes contributions to the IAM Plan trusts that cover certain union employees; contributions by employees are not permitted. Contributions to the IAM Plan were approximately $1.3 million in 2018 , $1.1 million in 2017 , and $1.1 million in 2016 . The Company’s contributions are less than five percent of total employer contributions made to the IAM Plan indicated in the most recently filed Form 5500. Under the Pension Protection Act of 2006, the IAM Plan’s actuary must certify the plan’s zone status annually. Plans in the red zone are generally less than 65 percent funded, plans in the yellow zone are less than 80 percent funded, and plans in the green zone are at least 80 percent funded. If a plan is determined to be in endangered status, red zone or yellow zone, the plan’s trustees must develop a formal plan of corrective action, a Financial Improvement Plan and/or a Rehabilitation Plan. For 2018 and 2017 the IAM Plan was determined to have green zone status; therefore, no formal plan of corrective action is either pending or has been implemented. 401(k) Plans The Company sponsors voluntary employee savings plans that qualify under Section 401(k) of the Internal Revenue Code of 1986. Compensation expense for the Company’s matching contribution to the 401(k) plans was $5.1 million in 2018 , $5.1 million in 2017 , and $5.2 million in 2016 . The Company match is a cash contribution. Participants direct the investment of their account balances by allocating among a range of asset classes including mutual funds (equity, fixed income, and balanced funds) and money market funds. The plans do not allow direct investment in securities issued by the Company. UMWA Benefit Plans In October 1992, the Coal Industry Retiree Health Benefit Act of 1992 (1992 Act) was enacted. The 1992 Act mandates a method of providing for postretirement benefits to the United Mine Workers of America (UMWA) current and retired employees, including some retirees who were never employed by the Company. In October 1993, beneficiaries were assigned to the Company and the Company began its mandated contributions to the UMWA Combined Benefit Fund, a multiemployer trust. Beginning in 1994, the Company was required to make contributions for assigned beneficiaries under an additional multiemployer trust created by the 1992 Act, the UMWA 1992 Benefit Plan. The ultimate amount of the Company’s liability under the 1992 Act will vary due to factors which include, among other things, the validity, interpretation, and regulation of the 1992 Act, its joint and several obligation, the number of valid beneficiaries assigned, and the extent to which funding for this obligation will be satisfied by transfers of excess assets from the 1950 UMWA pension plan and transfers from the Abandoned Mine Reclamation Fund. Contributions to the plan were $153 thousand , $182 thousand , and $197 thousand for the years ended 2018 , 2017 , and 2016 , respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 29, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Environmental The Company is subject to federal, state, local, and foreign environmental laws and regulations. For all properties, the Company has provided and charged to expense $2.0 million in 2018 , $7.5 million in 2017 , and $0.9 million in 2016 for pending environmental matters. Environmental reserves totaled $23.6 million at December 29, 2018 and $28.0 million at December 30, 2017 . As of December 29, 2018 , the Company expects to spend $3.6 million in 2019 , $0.6 million in 2020 , $0.6 million in 2021 , $0.6 million in 2022 , $0.7 million in 2023 , and $17.5 million thereafter for ongoing projects. 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. 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 the 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. 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 2029 to address residual discharges of acid rock drainage. At this site, MRRC spent approximately $1.4 million from 2016 through 2018 for remediation, and currently estimates that it will spend between approximately $12.8 million and $17.5 million over the next 30 years. 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. Lead Refinery spent approximately $0.7 million from 2016 through 2018 with respect to this site. Approximate costs to comply with the post-closure permit, including associated general and administrative costs, are estimated at between $1.7 million and $2.1 million over the next 18 years. 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 a financial guarantee in the amount of $1.0 million . 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 of year-end, the Company has made payments of $4.5 million related to the aforementioned agreement with the other PRPs and has included $2.5 million in the reserve for environmental liabilities as of December 29, 2018 . 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, a group of private plaintiffs sued the Company, Arava, MRRC, and Lead Refinery, along with other defendants, in a private tort action relating to the site; the Company, Arava, and MRRC were voluntarily dismissed from that litigation without prejudice in March 2018. A second civil action asserting similar claims was filed against the Company, Arava, MRRC, and Lead Refinery in September 2018. 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). 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 $0.7 million to $1.1 million over the next seven years. 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. Equal Employment Opportunity Commission Matter On October 5, 2016, the Company received a demand letter from the Los Angeles District Office of the United States Equal Employment Opportunity Commission (EEOC). The EEOC alleges that between May 2011 and April 2015, various Company employees were terminated in violation of the Americans with Disabilities Act (ADA), and that certain of the Company’s employee leave and attendance policies were discriminatory in nature. Thereafter, the Company, in consultation with its liability insurers, entered into conciliation and mediation efforts with the EEOC for purposes of resolving the claims. At the conclusion of those efforts, the Company and the EEOC reached agreement on a consensual resolution of the EEOC’s claims, which includes both monetary and equitable relief. On June 28, 2018, the EEOC filed a complaint against the Company on behalf of a group of unidentified claimants in the United States District Court for the Central District of California alleging that the Company engaged in unlawful employment practices in violation of the ADA. On July 13, 2018, the District Court approved a Consent Decree between the Company and the EEOC to resolve the EEOC’s claims. The Consent Decree, the term of which shall be two and a half years, provides that the Company shall pay up to $1.0 million in monetary relief to fund individual claims for discrimination under the ADA as approved by the EEOC. That amount is fully within the limits of the Company’s applicable insurance coverage. Pursuant to the Consent Decree, the Company shall also take a series of proactive measures to cultivate a work environment free from unlawful discrimination. Those measures include, among others, assistance with the identification of potential claimants, employee, supervisory and managerial training regarding employee rights under the ADA, revised practices and procedures concerning reasonable workplace accommodations as required by the ADA, and related reporting and recordkeeping. Deepwater Horizon Economic and Property Damage Claim In November 2018, an Appeal Panel of the Deepwater Horizon Economic and Property Damage Settlement Program approved an award to Mueller Copper Tube Company, Inc., a wholly owned subsidiary of the Company, of $27.4 million . In January 2019, the United States District Court for the Eastern District of Louisiana denied discretionary review of the award, and an appeal of the award is currently pending before the United States Court of Appeals for the Fifth Circuit. The award, if upheld, is subject to the Company’s payment of contingency-based legal and advisory fees of approximately 20 percent of the total award amount. Any recovery following the payment of such fees and any applicable taxes will be recognized as income when settled. There can be no assurance that the Company will receive such award, and it is possible such award will be materially reduced or reversed in its entirety upon appeal. Leases The Company leases certain facilities, vehicles, and equipment which expire on various dates through 2033 . The lease payments under these agreements aggregate to approximately $6.6 million in 2019 , $5.6 million in 2020 , $4.4 million in 2021 , $3.7 million in 2022 , $2.6 million in 2023 , and $15.4 million thereafter. Total lease expense amounted to $11.5 million in 2018 , $11.9 million in 2017 , and $11.6 million in 2016 . Other 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. It may also realize the benefit of certain legal claims and litigation in the future; these gain contingencies are not recognized in the Consolidated Financial Statements.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 29, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of income before income taxes were taxed under the following jurisdictions: (In thousands) 2018 2017 2016 Domestic $ 105,455 $ 76,876 $ 103,576 Foreign 44,962 50,096 42,454 Income before income taxes $ 150,417 $ 126,972 $ 146,030 Income tax expense consists of the following: (In thousands) 2018 2017 2016 Current tax expense: Federal $ 17,974 $ 28,584 $ 32,262 Foreign 9,650 10,219 5,667 State and local 3,158 2,241 3,210 Current tax expense 30,782 41,044 41,139 Deferred tax expense (benefit): Federal (1,381 ) (1,764 ) 2,004 Foreign 551 1,118 5,099 State and local 1,000 (2,514 ) (105 ) Deferred tax expense (benefit) 170 (3,160 ) 6,998 Income tax expense $ 30,952 $ 37,884 $ 48,137 The difference between the reported income tax expense and a tax determined by applying the applicable U.S. federal statutory income tax rate to income before income taxes is reconciled as follows: (In thousands) 2018 2017 2016 Expected income tax expense $ 31,588 $ 44,440 $ 51,110 State and local income tax, net of federal benefit 3,495 1,135 1,982 Effect of foreign statutory rates different from U.S. and other foreign adjustments 759 (6,026 ) (4,092 ) Changes in valuation allowances 1,133 — — U.S. production activities deduction — (1,575 ) (3,063 ) Investment in unconsolidated affiliates (3,909 ) 216 1,030 Benefit of stock-based compensation deductions (41 ) (2,160 ) (656 ) Effect of tax on accumulated foreign earnings (4,415 ) 12,893 — Effect of tax rate change on net deferred tax liability balance — (12,067 ) — Other, net 2,342 1,028 1,826 Income tax expense $ 30,952 $ 37,884 $ 48,137 The Tax Cuts and Jobs Act (the Act) was enacted on December 22, 2017. The Act reduced the U.S. federal corporate income tax rate from 35 percent to 21 percent, required companies to pay a one-time transition tax on the accumulated earnings of certain foreign subsidiaries, and created new taxes on certain foreign-sourced earnings. The Company applied the guidance in Staff Accounting Bulletin No. 118 in accounting for the enactment date effects of the Act. At December 30, 2017 , the Company made a reasonable estimate of the one-time transition tax on accumulated foreign earnings as well as the impact of the Act on its existing deferred tax balances. During the fourth quarter of 2018 , the Company completed its accounting for all of the enactment-date income tax effects of the Act. The one-time transition tax is based on the Company’s total post-1986 earnings and profits (E&P) for which the accrual of U.S. income taxes had previously been deferred. The Company recorded a provisional amount for its one-time transition tax liability, resulting in an increase in income tax expense of $12.9 million , or 22 cents per diluted share, at December 30, 2017 . During 2018 , the Company finalized its calculation of the post-1986 E&P as well as the cash balances of the foreign subsidiaries whose earnings were subject to the transition tax. Following the completion of this analysis, the Company recorded a reduction to income tax expense of $4.4 million , or eight cents per diluted share, to reduce this liability. Subsequent to the Company’s year-end, the Treasury Department finalized regulations related to the calculation of the transition tax, and the Company is analyzing the impact of these regulations on its calculation of the transition tax. The Company continues to assert that the undistributed earnings of most of its foreign subsidiaries are permanently reinvested. No additional tax liability has been accrued with respect to the earnings of any of these foreign subsidiaries. If these undistributed earnings were remitted from these foreign subsidiaries to the U.S., the Company would pay additional tax of approximately $4.0 million . No additional income taxes have been provided for any additional outside bases differences inherent in these entities, as these amounts continue to be indefinitely reinvested in foreign operations. Determining the amount of unrecognized deferred tax liability related to any additional outside basis differences in these entities is not practicable. On December 30, 2017 , the Company remeasured certain deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21 percent, resulting in an income tax benefit of $12.1 million , or 21 cents per diluted share. The Company has concluded that no further adjustment is needed related to this remeasurement. The global intangible low-taxed income (GILTI) provisions of the Act impose a tax on the GILTI earned by certain foreign subsidiaries. The FASB Staff Q&A, Topic 740, No. 5, Accounting for Global Intangible Low-Taxed Income , states that an entity can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI in the year the tax is incurred. The Company has elected to provide for the tax expense related to GILTI in the year the tax is incurred. In 2018 , this amount was not material to the Consolidated Financial Statements. The Company includes interest and penalties related to income tax matters as a component of income tax expense. The income tax expense related to penalties and interest was immaterial in 2018 , 2017 , and 2016 . The Internal Revenue Service completed its audit of the Company’s 2013 tax return during 2016, the results of which were immaterial to the Consolidated Financial Statements. The statute of limitations is open for the Company’s federal tax return and most state income tax returns for 2015 and all subsequent years. The statutes of limitations for certain state and foreign returns are also open for some earlier tax years due to differing statute periods. 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. The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities are presented below: (In thousands) 2018 2017 Deferred tax assets: Inventories $ 12,297 $ 10,598 Other postretirement benefits and accrued items 9,213 9,239 Other reserves 7,847 9,029 Federal and foreign tax attributes 6,252 11,936 State tax attributes, net of federal benefit 27,651 29,720 Stock-based compensation 2,949 2,102 Basis difference in unconsolidated affiliates 1,067 — Total deferred tax assets 67,276 72,624 Less valuation allowance (25,311 ) (30,316 ) Deferred tax assets, net of valuation allowance 41,965 42,308 Deferred tax liabilities: Property, plant, and equipment 44,910 43,972 Pension 250 3,841 Basis difference in unconsolidated affiliates — 203 Total deferred tax liabilities 45,160 48,016 Net deferred tax liabilities $ (3,195 ) $ (5,708 ) As of December 29, 2018 , after consideration of the federal impact, the Company had state income tax credit carryforwards of $4.3 million , all of which expire by 2021, and other state income tax credit carryforwards of $11.7 million with unlimited lives. The Company had state net operating loss (NOL) carryforwards with potential tax benefits of $11.6 million , after consideration of the federal impact, expiring between 2019 and 2033. The state tax credit and NOL carryforwards are offset by valuation allowances totaling $16.0 million . As of December 29, 2018 , the Company had other foreign tax attributes with potential tax benefits of $5.8 million that have an unlimited life. These attributes were fully offset by a valuation allowance. Income taxes paid were approximately $38.1 million in 2018 , $42.5 million in 2017 , and $40.1 million in 2016 .

Equity

Equity	12 Months Ended
	Dec. 29, 2018
Equity [Abstract]
Equity	Equity The Company’s Board of Directors has extended, until August 2019 , its authorization to repurchase up to 20 million shares of the Company’s common stock through open market transactions or through privately negotiated transactions. The Company has no obligation to purchase any shares and may cancel, suspend, or extend the time period for the purchase of shares at any time. Any purchases will be funded primarily through existing cash and cash from operations. The Company may hold any shares purchased in treasury or use a portion of the repurchased shares for its stock-based compensation plans, as well as for other corporate purposes. From its initial authorization in 1999 through December 29, 2018 , the Company has repurchased approximately 6.1 million shares under this authorization.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 29, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation The Company has in effect stock incentive plans under which stock-based awards have been granted to certain employees and members of its Board of Directors. Under these existing plans, the Company may grant options to purchase shares of common stock at prices not less than the fair market value of the stock on the grant date, as well as restricted stock awards. Generally, the awards vest within five years from the grant date. Any unexercised options expire after not more than ten years . During the years ended December 29, 2018 , December 30, 2017 , and December 31, 2016 , the Company recognized stock-based compensation, as a component of selling, general, and administrative expense, in its Consolidated Statements of Income of $8.0 million , $7.5 million , and $6.4 million , respectively. Stock Options The fair value of each option is estimated as a single award and amortized into compensation expense on a straight-line or accrual basis over its vesting period based on its vesting schedule. The weighted average grant-date fair value of options granted during 2018 , 2017 , and 2016 was $9.64 , $9.38 , and $7.87 , respectively. The Company estimates the fair value of all stock option awards as of the grant date by applying the Black-Scholes-Merton option pricing model. The use of this valuation model in the determination of compensation expense involves certain assumptions that are judgmental and/or highly sensitive including the expected life of the option, stock price volatility, risk-free interest rate, and dividend yield. Additionally, forfeitures are not estimated at the time of valuation; they are recognized as they occur. The weighted average of key assumptions used in determining the fair value of options granted and a discussion of the methodology used to develop each assumption are as follows: 2018 2017 2016 Expected term 7.6 years 7.7 years 6.7 years Expected price volatility 27.2 % 28.9 % 25.6 % Risk-free interest rate 2.9 % 2.1 % 1.6 % Dividend yield 1.3 % 1.3 % 1.0 % Expected term – This is the period of time estimated based on historical experience over which the options granted are expected to remain outstanding. An increase in the expected term will increase compensation expense. Expected price volatility – This is a measure of the amount by which a price has fluctuated or is expected to fluctuate. The Company uses actual historical changes in the market value of its stock to calculate the volatility assumption. Daily market value changes from the grant date over a past period representative of the expected term of the options are used. An increase in the expected price volatility rate will increase compensation expense. Risk-free interest rate – This is the U.S. Treasury rate for the week of the grant, having a term representative of the expected term of the options. An increase in the risk-free rate will increase compensation expense. Dividend yield – This rate is the annual dividends per share as a percentage of the Company’s stock price. An increase in the dividend yield will decrease compensation expense. The total intrinsic value of options exercised was $0.9 million , $10.2 million , and $2.5 million in 2018 , 2017 , and 2016 , respectively. The total fair value of options that vested was $1.0 million , $1.0 million , and $0.3 million in 2018 , 2017 , and 2016 , respectively. At December 29, 2018 , the aggregate intrinsic value of all outstanding options was $2.7 million with a weighted average remaining contractual term of 6.0 years. Of the outstanding options, 562 thousand are currently exercisable with an aggregate intrinsic value of $2.7 million , a weighted average exercise price of $19.87 , and a weighted average remaining contractual term of 4.5 years. The total compensation expense not yet recognized related to unvested options at December 29, 2018 was $2.2 million , with an average expense recognition period of 3.8 years. Restricted Stock Awards The fair value of each restricted stock award equals the fair value of the Company’s stock on the grant date and is amortized into compensation expense on a straight-line or accrual basis over its vesting period based on its vesting schedule. The weighted average grant-date fair value of awards granted during 2018 , 2017 , and 2016 was $32.04 , $30.97 , and $34.04 , respectively. The aggregate intrinsic value of outstanding and unvested awards was $21.8 million at December 29, 2018 . Total compensation expense for restricted stock awards not yet recognized was $17.5 million with an average expense recognition period of 3.2 years. The total fair value of awards that vested was $3.7 million , $3.5 million , and $4.7 million in 2018 , 2017 , and 2016 , respectively. The Company generally issues treasury shares when options are exercised or restricted stock awards are granted. A summary of the activity and related information follows: Stock Options Restricted Stock Awards (Shares in thousands) Shares Weighted Average Exercise Price Shares Weighted Average Grant Date Fair Value Outstanding at December 30, 2017 947 $ 22.31 781 $ 31.83 Granted 142 31.33 276 32.04 Exercised/Released (57 ) 15.10 (124 ) 29.95 Forfeited (18 ) 26.78 (3 ) 32.60 Outstanding at December 29, 2018 1,014 23.90 930 32.14 Approximately 344 thousand shares were available for future stock incentive awards at December 29, 2018 .

Accumulated Other Comprehensive

Accumulated Other Comprehensive Income (Loss)	12 Months Ended
	Dec. 29, 2018
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, unrealized gains and losses on marketable securities classified as available-for-sale, and other comprehensive income attributable to unconsolidated affiliates. The following table provides changes in AOCI by component, net of taxes and noncontrolling interest (amounts in parentheses indicate debits to AOCI): (In thousands) Cumulative Translation Adjustment Unrealized (Loss) Gain on Derivatives Pension/ Unrealized Gain (Loss) on Equity Securities Attributable to Unconsol. Affiliates Total Balance at December 31, 2016 $ (49,965 ) $ (300 ) $ (23,046 ) $ 380 $ 5,975 $ (66,956 ) Other comprehensive income (loss) before reclassifications 15,579 (389 ) 1,394 (1 ) 895 17,478 Amounts reclassified from AOCI (3,777 ) 1,536 1,042 (379 ) — (1,578 ) Balance at December 30, 2017 (38,163 ) 847 (20,610 ) — 6,870 (51,056 ) Other comprehensive loss before reclassifications (16,094 ) (802 ) (3,642 ) — (8,686 ) (29,224 ) Amounts reclassified from AOCI — (371 ) 303 — — (68 ) Net current-period other comprehensive loss (16,094 ) (1,173 ) (3,339 ) — (8,686 ) (29,292 ) Reclassification of stranded effects of the Act — 112 (1,018 ) — 1,462 556 Balance at December 29, 2018 $ (54,257 ) $ (214 ) $ (24,967 ) $ — $ (354 ) $ (79,792 ) Reclassification adjustments out of AOCI were as follows: Amount reclassified from AOCI (In thousands) 2018 2017 2016 Affected Line Item Unrealized losses (gains) on derivatives: Commodity contracts $ (429 ) $ 1,309 $ 1,061 Cost of goods sold Interest rate swap — 851 361 Interest expense 58 (624 ) (113 ) Income tax expense (benefit) $ (371 ) $ 1,536 $ 1,309 Net of tax and noncontrolling interests Amortization of net loss and prior service cost on employee benefit plans $ 341 $ 1,263 $ 1,942 Other income, net (38 ) (221 ) (521 ) Income tax benefit $ 303 $ 1,042 $ 1,421 Net of tax and noncontrolling interests Gain recognized upon sale of business $ — $ (3,777 ) $ — Gain on sale of assets — — — Income tax expense $ — $ (3,777 ) $ — Net of tax and noncontrolling interests Sale of available-for-sale securities $ — $ (611 ) $ — Other income, net — 232 — Income tax expense $ — $ (379 ) $ — Net of tax and noncontrolling interests

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 29, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited) (1) (In thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter 2018 Net sales $ 640,060 $ 662,773 $ 645,958 $ 559,087 Gross profit (2) 94,390 98,953 79,002 85,133 Consolidated net income (3) 24,344 33,882 20,863 27,731 Net income attributable to Mueller Industries, Inc. 24,128 33,182 20,292 26,857 Basic earnings per share 0.42 0.58 0.36 0.47 Diluted earnings per share 0.42 0.58 0.35 0.47 Dividends per share 0.10 0.10 0.10 0.10 2017 Net sales $ 577,920 $ 614,266 $ 550,363 $ 523,524 Gross profit (2) 89,493 89,955 79,101 66,907 Consolidated net income (4) 30,455 27,833 22,754 5,969 (5) Net income attributable to Mueller Industries, Inc. 29,987 27,633 22,258 5,720 Basic earnings per share 0.53 0.49 0.39 0.10 Diluted earnings per share 0.52 0.48 0.39 0.10 Dividends per share 8.10 0.10 0.10 0.10 (1) The sum of quarterly amounts may not equal the annual amounts reported due to rounding. In addition, the earnings per share amounts are computed independently for each quarter, while the full year is based on the weighted average shares outstanding. (2) Gross profit is net sales less cost of goods sold, which excludes depreciation and amortization. (3) Includes income earned by ATCO, acquired during Q3 2018, and Die-Mold, acquired during Q1 2018. (4) Includes income earned by Heatlink Group, acquired during Q2 2017. (5) Includes $1.1 million of pre-tax charges related to asset impairments, $4.3 million of interest expense on the Company’s Subordinated Debentures, and pre-tax environmental expense for non-operating properties of $6.2 million .

SCHEDULE II-VALUATION AND QUALI

SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS	12 Months Ended
	Dec. 29, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS	MUELLER INDUSTRIES, INC. SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS Years Ended December 29, 2018 , December 30, 2017 , and December 31, 2016 Additions (In thousands) Balance at beginning of year Charged to costs and expenses Other additions Deductions Balance at end of year 2018 Allowance for doubtful accounts $ 980 $ (286 ) $ 220 $ 78 $ 836 Environmental reserves $ 28,004 $ 1,981 $ — $ 6,366 $ 23,619 Valuation allowance for deferred tax assets $ 30,316 $ 1,209 $ 150 $ 6,364 $ 25,311 2017 Allowance for doubtful accounts $ 637 $ 422 $ (61 ) $ 18 $ 980 Environmental reserves $ 21,864 $ 7,491 $ — $ 1,351 $ 28,004 Valuation allowance for deferred tax assets $ 18,681 $ 7 $ 11,628 (1) $ — $ 30,316 2016 Allowance for doubtful accounts $ 623 $ 160 $ 2 $ 148 $ 637 Environmental reserves $ 21,667 $ 894 $ — $ 697 $ 21,864 Valuation allowance for deferred tax assets $ 17,650 $ 3 $ 1,028 $ — $ 18,681 (1) The valuation allowance increased by $11.6 million during 2017 to a balance of $30.3 million as of December 30, 2017. The change to the valuation allowance was attributable to the recording of valuation allowances against tax attributes generated in 2017 primarily resulting from the Act and increased interest expense in state tax jurisdictions where the Company has no tax liability.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 29, 2018
Accounting Policies [Abstract]
Fiscal Years	Fiscal Years The Company’s fiscal year ends on the last Saturday of December, and consisted of 52 weeks in 2018 and 2017 , compared to 53 weeks in 2016 . These dates were December 29, 2018 , December 30, 2017 , and December 31, 2016 .
Basis of Presentation	Basis of Presentation The Consolidated Financial Statements include the accounts of Mueller Industries, Inc. and its majority-owned subsidiaries. The noncontrolling interests represent separate private ownership interests of 40 percent of Jungwoo Metal Ind. Co., LTD (Jungwoo-Mueller) and 49.5 percent of Jiangsu Mueller-Xingrong Copper Industries Limited (Mueller-Xingrong), which the Company sold during 2017 .
Revenue Recognition	Revenue Recognition Given the nature of the Company’s business and product offerings, sales transactions with customers are generally comprised of a single performance obligation that involves delivery of the products identified in the contracts with customers. Performance obligations are generally satisfied at the point in time of shipment and payment is generally due within sixty days. Variable consideration is estimated for future rebates on certain product lines and product returns. The Company records variable consideration as an adjustment to the transaction price in the period it is incurred. Since variable consideration is settled within a short period of time, the time value of money is not significant. The cost of shipping product to customers is expensed as incurred as a component of cost of goods sold.
Acquisitions	Acquisitions Accounting for acquisitions requires the Company to recognize separately from goodwill the assets acquired and liabilities assumed at their acquisition date fair values. Goodwill is measured as the excess of the purchase price over the net amount allocated to the identifiable assets acquired and liabilities assumed. While management uses its best estimates and assumptions to accurately value assets acquired and liabilities assumed at the acquisition date, the estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, which may be up to one year from the acquisition date, the Company may record adjustments to the assets acquired and liabilities assumed with the corresponding offset to goodwill. The operating results generated by the acquired businesses are included in the Consolidated Statements of Income from their respective dates of acquisition. Acquisition related costs are expensed as incurred.
Cash Equivalents	Cash Equivalents and Restricted Cash Temporary investments with original maturities of three months or less are considered to be cash equivalents. These investments are stated at cost. At December 29, 2018 and December 30, 2017 , temporary investments consisted of money market mutual funds, commercial paper, bank repurchase agreements, and U.S. and foreign government securities totaling approximately $0.6 million each year. Included in other current assets was restricted cash of $4.4 million and $6.2 million at December 29, 2018 and December 30, 2017 , respectively. These amounts represent required deposits into brokerage accounts that facilitate the Company’s hedging activities as well as imprest funds for the Company’s self-insured workers’ compensation program.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts The Company provides an allowance for receivables that may not be fully collected. In circumstances where the Company is aware of a customer’s inability to meet their financial obligations (e.g., bankruptcy filings or substantial credit rating downgrades), it records an allowance for doubtful accounts against amounts due to reduce the net recognized receivable to the amount it believes most likely will be collected. For all other customers, the Company recognizes an allowance for doubtful accounts based on its historical collection experience. If circumstances change (e.g., greater than expected defaults or an unexpected material change in a major customer’s ability to meet their financial obligations), the Company could change its estimate of the recoverability of amounts due by a material amount.
Inventories	Inventories The Company’s inventories are valued at the lower-of-cost-or-market. The material component of its U.S. copper tube and copper fittings inventories is valued on a LIFO basis and the non-material components of U.S. copper tube and copper fittings inventories are valued on a FIFO basis. The material component of its U.K. and Canadian copper tube inventories are valued on a FIFO basis. The material component of its brass rod and forgings inventories are valued on a FIFO basis. Certain inventories purchased for resale are valued on an average cost basis. Elements of cost in finished goods inventory in addition to the cost of material include depreciation, amortization, utilities, maintenance, production wages, and transportation costs. The market price of copper cathode and scrap is subject to volatility. During periods when open market prices decline below net book value, the Company may need to provide an allowance to reduce the carrying value of its inventory. In addition, certain items in inventory may be considered obsolete and, as such, the Company may establish an allowance to reduce the carrying value of those items to their net realizable value. Changes in these estimates related to the value of inventory, if any, may result in a materially adverse impact on the Company’s reported financial position or results of operations. The Company recognizes the impact of any changes in estimates, assumptions, and judgments in income in the period in which it is determined.
Property, Plant, and Equipment	Property, Plant, and Equipment Property, plant, and equipment is stated at cost less accumulated depreciation. Expenditures for major additions and improvements are capitalized, while minor replacements, maintenance, and repairs are charged to expense as incurred. Depreciation of buildings, machinery, and equipment is provided on the straight-line method over the estimated useful lives ranging from 20 to 40 years for buildings and five to 20 years for machinery and equipment. Leasehold improvements are amortized over the lesser of their useful life or the remaining lease term. The Company continually evaluates these assets to determine whether events or changes in circumstances have occurred that may warrant revision of the estimated useful life or whether the remaining balance should be evaluated for possible impairment.
Goodwill	Goodwill Goodwill is recognized for the excess of the purchase price over the fair value of tangible and identifiable intangible net assets of businesses acquired. Several factors give rise to goodwill in business acquisitions, such as the expected benefit from synergies of the combination and the existing workforce of the acquired business. Goodwill is evaluated annually for possible impairment as of the first day of the fourth quarter unless circumstances indicate the need to accelerate the timing of the evaluation. In the evaluation of goodwill impairment, management performs a qualitative assessment to determine if it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If the qualitative assessment is not conclusive, management compares the fair value of a reporting unit with its carrying amount and will recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, not to exceed the total amount of goodwill allocated to the reporting unit. Fair value for the Company’s reporting units is determined using a combination of the income and market approaches (level 3 within the fair value hierarchy), incorporating market participant considerations and management’s assumptions on revenue growth rates, operating margins, discount rates and expected capital expenditures. The market approach measures the fair value of a business through the analysis of publicly traded companies or recent sales of similar businesses. The income approach uses a discounted cash flow model to estimate the fair value of reporting units based on expected cash flows (adjusted for capital investment required to support operations) and a terminal value. This cash flow stream is discounted to its present value to arrive at a fair value for each reporting unit. Future earnings are estimated using the Company’s most recent annual projections, applying a growth rate to future periods. Those projections are directly impacted by the condition of the markets in which the Company’s businesses participate. The discount rate selected for the reporting units is generally based on rates of return available for comparable companies at the date of valuation. Fair value determinations may include both internal and third-party valuations.
Investment in Unconsolidated Affiliate	Investments in Unconsolidated Affiliates The Company owns a 50 percent interest in an unconsolidated affiliate that acquired Tecumseh Products Company (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 Consolidated Statements of Income. The Company’s proportionate share of the investees’ other comprehensive income (loss), net of income taxes, is recorded in the Consolidated Statements of Comprehensive Income and 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 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 Company also owns a 40 percent interest in Mueller Middle East BSC. The investments in unconsolidated affiliates are assessed periodically for impairment and written down when the carrying amount is not considered fully recoverable.
Self-Insurance Accruals	Self-Insurance Accruals The Company is primarily self-insured for workers’ compensation claims and benefits paid under certain employee health care programs. Accruals are primarily based on estimated undiscounted cost of claims, which includes incurred but not reported claims, and are classified as accrued wages and other employee costs.
Pension and Other Postretirement Benefit Plans	Pension and Other Postretirement Benefit Plans The Company sponsors several qualified and nonqualified pension and other postretirement benefit plans in the U.S. and certain foreign locations. The Company recognizes the overfunded or underfunded status of the plans as an asset or liability in the Consolidated Balance Sheets with changes in the funded status recorded through comprehensive income in the year in which those changes occur. The obligations for these plans are actuarially determined and affected by assumptions, including discount rates, expected long-term return on plan assets for defined benefit pension plans, and certain employee-related factors, such as retirement age and mortality. The Company evaluates its assumptions periodically and makes adjustments as necessary. The expected return on plan assets is determined using the market value of plan assets. Differences between assumed and actual returns are amortized to the market value of assets on a straight-line basis over the average remaining service period of the plan participants using the corridor approach. The corridor approach defers all actuarial gains and losses resulting from variances between actual results and actuarial assumptions. These unrecognized gains and losses are amortized when the net gains and losses exceed 10 percent of the greater of the market value of the plan assets or the projected benefit obligation. The amount in excess of the corridor is amortized over the average remaining service period of the plan participants. For 2018 , the average remaining service period for the pension plans was nine years .
Environmental Reserves and Environmental Expenses	Environmental Reserves and Environmental Expenses The Company recognizes an environmental liability when it is probable the liability exists and the amount is reasonably estimable. The Company estimates the duration and extent of its remediation obligations based upon reports of outside consultants, internal and third party estimates and analyses of cleanup costs and ongoing monitoring costs, communications with regulatory agencies, and changes in environmental law. If the Company were to determine that its estimates of the duration or extent of its environmental obligations were no longer accurate, it would adjust environmental liabilities accordingly in the period that such determination is made. Estimated future expenditures for environmental remediation are not discounted to their present value. Environmental expenses that relate to ongoing operations are included as a component of cost of goods sold. Environmental expenses related to non-operating properties are presented below operating income in the Consolidated Statements of Income.
Earnings Per Share	Earnings Per Share Basic earnings per share is computed based on the weighted average number of common shares outstanding. Diluted earnings per share reflects the increase in weighted average common shares outstanding that would result from the assumed exercise of outstanding stock options and vesting of restricted stock awards calculated using the treasury stock method.
Income Taxes	Income Taxes Deferred income tax assets and liabilities are recognized when differences arise between the treatment of certain items for financial statement and tax purposes. Realization of certain components of deferred tax assets is dependent upon the occurrence of future events. The Company records valuation allowances to reduce its deferred tax assets to the amount it believes is more likely than not to be realized. These valuation allowances can be impacted by changes in tax laws, changes to statutory tax rates, and future taxable income levels and are based on the Company’s judgment, estimates, and assumptions regarding those future events. In the event the Company was to determine that it would not be able to realize all or a portion of the net deferred tax assets in the future, it would increase the valuation allowance through a charge to income tax expense in the period that such determination is made. Conversely, if it was to determine that it would be able to realize its deferred tax assets in the future, in excess of the net carrying amounts, the Company would decrease the recorded valuation allowance through a decrease to income tax expense in the period that such determination is made. The Company provides for uncertain tax positions and the related interest and penalties, if any, based upon management’s assessment of whether a tax benefit is more likely than not to be sustained upon examination by tax authorities. Tax benefits for uncertain tax positions that are recognized in the financial statements are measured as the largest amount of benefit, determined on a cumulative probability basis, that is more likely than not to be realized upon ultimate settlement. To the extent the Company prevails in matters for which a liability for an uncertain tax position is established or is required to pay amounts in excess of the liability, the Company’s effective tax rate in a given financial statement period may be affected. These estimates are highly subjective and could be affected by changes in business conditions and other factors. Changes in any of these factors could have a material impact on future income tax expense.
Taxes Collected from Customers and Remitted to Governmental Authorities	Taxes Collected from Customers and Remitted to Governmental Authorities Taxes assessed by a governmental authority that are directly imposed on a revenue producing transaction between the Company and its customers, primarily value added taxes in foreign jurisdictions, are accounted for on a net (excluded from revenues and costs) basis.
Stock-Based Compensation	Stock-Based Compensation The Company has in effect stock incentive plans under which stock-based awards have been granted to certain employees and members of its Board of Directors. Stock-based compensation expense is recognized in the Consolidated Statements of Income as a component of selling, general, and administrative expense based on the grant date fair value of the awards.
Concentrations of Credit and Market Risk	Concentrations of Credit and Market Risk Concentrations of credit risk with respect to accounts receivable are limited due to the large number of customers comprising the Company’s customer base, and their dispersion across different geographic areas and different industries, including HVAC, plumbing, refrigeration, hardware, automotive, OEMs, and others. The Company minimizes its exposure to base metal price fluctuations through various strategies. Generally, it prices an equivalent amount of copper raw material, under flexible pricing arrangements it maintains with its suppliers, at the time it determines the selling price of finished products to its customers.
Derivative Instruments and Hedging Activities	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 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 (i) a forecasted transaction or the variability of cash flow to be paid (cash flow hedge) or (ii) the fair value of a recognized asset or liability (fair value 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 accumulated other comprehensive income (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 a derivative that is qualified, designated, and highly effective as a fair value hedge, along with the gain or loss on the hedged recognized asset or liability that is attributable to the hedged risk, are recorded in current earnings. Changes in the fair value of undesignated derivative instruments executed as economic hedges and the ineffective portion of designated derivatives 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 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 flow 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. The Company primarily executes derivative contracts with major financial institutions. These counterparties expose the Company to credit risk in the event of non-performance. The amount of such exposure is limited to the fair value of the contract plus the unpaid portion of amounts due to the Company pursuant to terms of the derivative instruments, if any. If a downgrade in the credit rating of these counterparties occurs, management believes that this exposure is mitigated by provisions in the derivative arrangements which allow for the legal right of offset of any amounts due to the Company from the counterparties with any amounts payable to the counterparties by the Company. As a result, management considers the risk of loss from counterparty default to be minimal.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts for cash and cash equivalents, accounts receivable, and accounts payable approximate fair value due to the short-term maturity of these instruments. The fair value of long-term debt at December 29, 2018 approximates the carrying value on that date. The estimated fair values were determined based on quoted market prices and the current rates offered for debt with similar terms and maturities. The fair value of long-term debt is classified as level 2 within the fair value hierarchy. This classification is defined as a fair value determined using market-based inputs other than quoted prices that are observable for the liability, either directly or indirectly.
Foreign Currency Translation	Foreign Currency Translation For foreign subsidiaries for which the functional currency is not the U.S. dollar, balance sheet accounts are translated at exchange rates in effect at the end of the year and income statement accounts are translated at average exchange rates for the year. Translation gains and losses are included in equity as a component of AOCI. Transaction gains and losses that arise from exchange rate fluctuations on transactions denominated in a currency other than the functional currency are recognized in selling, general, and administrative expense in the Consolidated Statements of Income.
Use of and Changes in Estimates	Use of and Changes in Estimates The preparation of financial statements in conformity with generally accepted accounting principles in the United States (U.S. GAAP) requires management to make estimates, assumptions, and judgments that affect the amounts reported in the financial statements and accompanying notes. Management makes its best estimate of the ultimate outcome for these items based on historical trends and other information available when the financial statements are prepared. Changes in estimates are recognized in accordance with the accounting rules for the estimate, which is typically in the period when new information becomes available to management. Areas where the nature of the estimate makes it reasonably possible that actual results could materially differ from amounts estimated include but are not limited to: pension and other postretirement benefit plan obligations, tax liabilities, loss contingencies, litigation claims, environmental reserves, and impairment assessments of long-lived assets (including goodwill).
Recently Issued Accounting Standards	Recently Issued Accounting Standards In August 2018, the FASB issued ASU No. 2018-14, Compensation - Retirement Benefits - Defined Benefit Plans - General (Subtopic 715-20): Disclosure Framework - Changes to the Disclosure Requirements for Defined Benefit Plans . For employers that sponsor defined benefit pension and/or other postretirement benefit plans, the ASU eliminates requirements for certain disclosures that are no longer considered cost beneficial, requires new disclosures related to the weighted-average interest crediting rate for cash balance plans and explanations for significant gains and losses related to changes in benefit obligations, and clarifies the requirements for entities that provide aggregate disclosures for two or more plans. The ASU will be effective for the annual period beginning in 2020. 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 Consolidated Financial Statements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement . The ASU eliminates requirements to disclose the amount and reasons for transfers between level 1 and level 2 of the fair value hierarchy, but requires public companies to disclose changes in unrealized gains and losses for the period included in other comprehensive income (OCI) for recurring level 3 fair value measurements or instruments held at the end of the reporting period and the range and weighted average used to develop significant unobservable inputs for level 3 fair value measurements. The ASU will be effective for interim and annual periods beginning in 2020. An entity is permitted to early adopt either the entire standard or only the provisions that eliminate or modify requirements, and can elect to early adopt in interim periods. The guidance on changes in unrealized gains and losses for the period included in OCI for recurring level 3 measurements, the range and weighted average of significant unobservable inputs used to develop level 3 fair value measurements, and the narrative description of measurement uncertainty is applied prospectively. All other amendments should be applied retrospectively. The Company does not expect the adoption of the ASU to have a material impact on its Consolidated Financial Statements. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements and ASU No. 2018-10, Codification Improvements to Topic 842, Leases . The ASUs provide entities with relief from the costs of implementation and clarify how to apply certain aspects of the new leasing standard, ASC 842. ASC 842 requires an entity to recognize a right-of-use asset and lease liability for all leases with terms of more than 12 months. Recognition, measurement and presentation of expenses will depend on classification as a financing or operating lease. The guidance also requires certain quantitative and qualitative disclosures about leasing arrangements. The ASU will be effective for interim and annual periods beginning in 2019. Early adoption is permitted. ASC 842 requires a modified retrospective adoption, but ASU 2018-11 amends ASC 842 so that entities may elect not to recast their comparative periods in transition and allows entities to change their date of initial application to the beginning of the period of adoption. The future minimum lease payments under noncancelable leases were approximately $38.3 million and $40.5 million as of December 29, 2018 and December 30, 2017 , respectively. The Company has implemented a system to identify its entire population of leases and tested the population for completeness. The Company is still evaluating all of the effects that the provisions of the ASUs and the ASC will have on its Consolidated Financial Statements, but estimates that the right-of-use asset and lease liability will be approximately $25.0 million to $35.0 million .

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 29, 2018
Accounting Policies [Abstract]
Schedule of cash and cash equivalents	A reconciliation of cash, cash equivalents, and restricted cash for the periods presented is as follows: (In thousands) December 29, December 30, Cash & cash equivalents $ 72,616 $ 120,269 Restricted cash included within other current assets 4,414 6,189 Restricted cash included within other assets 108 105 Total cash, cash equivalents, and restricted cash $ 77,138 $ 126,563
Schedule of restricted cash	A reconciliation of cash, cash equivalents, and restricted cash for the periods presented is as follows: (In thousands) December 29, December 30, Cash & cash equivalents $ 72,616 $ 120,269 Restricted cash included within other current assets 4,414 6,189 Restricted cash included within other assets 108 105 Total cash, cash equivalents, and restricted cash $ 77,138 $ 126,563

Acquisitions and Dispositions (

Acquisitions and Dispositions (Tables)	12 Months Ended
	Dec. 29, 2018
Business Combinations [Abstract]
Business Acquisition, Pro Forma Information	The following table presents condensed pro forma consolidated results of operations as if the ATCO acquisition has occurred at the beginning of 2017. The pro forma information does not purport to be indicative of the results that would have been obtained if the operations had actually been combined during the periods presented, and is not necessarily indicative of operating results to be expected in future periods. The most significant pro forma adjustments to the historical results of operations relate to the application of purchase accounting and the financing structure. For the Year Ended (In thousands, except per share data) 2018 2017 Net sales $ 2,595,454 $ 2,431,972 Net income 111,482 90,270 Basic earnings per share $ 1.96 $ 1.59 Diluted earnings per share 1.95 1.57
Schedule of final valuation of the long-lived assets	The following table summarizes the allocation of the purchase price to acquire these businesses, which were financed by available cash balances, as well as the assets acquired and liabilities assumed at the respective acquisition dates. The purchase price allocation for ATCO is provisional as of December 29, 2018 and subject to change upon completion of the final valuation of the long-lived assets, contingent consideration, and final working capital adjustment during the measurement period. During 2018 , the valuation of the Heatlink Group acquisition was finalized. Changes to the purchase price allocation from the amounts presented in the Company’s 2017 Annual Report on Form 10-K included the valuation of the contingent consideration of $0.9 million and the recognition of a deferred tax liability of $1.9 million that resulted from a basis difference in the long-lived assets acquired. These changes resulted in an increase to goodwill. (in thousands) ATCO Die-Mold Heatlink Group Jungwoo-Mueller Total consideration $ 156,704 $ 13,629 $ 17,164 $ 20,533 Allocated to: Accounts receivable 21,829 1,684 2,809 5,551 Inventories 31,666 1,833 4,648 17,616 Other current assets 1,051 267 508 1,437 Property, plant, and equipment 83,080 3,278 2,024 24,191 Goodwill 17,770 (1) 2,241 6,879 223 Intangible assets 21,430 5,209 6,413 756 Other assets 224 — — 277 Total assets acquired 177,050 14,512 23,281 50,051 Accounts payable 8,093 710 3,633 7,252 Other current liabilities 10,187 173 593 577 Long-term debt 2,066 — — 8,659 Pension and other postretirement liabilities — — — 799 Other noncurrent liabilities — — 1,891 582 Total liabilities assumed 20,346 883 6,117 17,869 Noncontrolling interest — — — 11,649 Net assets acquired $ 156,704 $ 13,629 $ 17,164 $ 20,533 (1) Tax-deductible goodwill
Intangible assets identified in the allocation of the purchase price	The following details the total intangible assets identified in the allocation of the purchase price at the respective acquisition dates: (in thousands) Estimated Useful Life ATCO Die-Mold Heatlink Group Jungwoo-Mueller Intangible asset type: Customer relationships 20 years $ 6,200 $ 3,077 $ 4,265 $ — Non-compete agreements 3-5 years — 70 74 — Patents and technology 10-15 years 8,950 1,512 1,466 756 Trade names, licenses, and other 5-10 years 3,960 550 608 — Supply contracts 5 years 2,320 — — — Total intangible assets $ 21,430 $ 5,209 $ 6,413 $ 756

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 29, 2018
Segment Reporting [Abstract]
Net sales by major product line	The following tables represent a disaggregation of revenue from contracts with customers, along with the reportable segment for each category: For the Year Ended December 29, 2018 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 1,352,875 $ — $ — $ 1,352,875 Brass rod and forgings — 501,472 — 501,472 OEM components, tube & assemblies 29,578 53,581 139,113 222,272 Valves and plumbing specialties 263,180 — — 263,180 Other — 96,008 89,956 185,964 $ 1,645,633 $ 651,061 $ 229,069 $ 2,525,763 Intersegment sales (17,885 ) Net sales $ 2,507,878 For the Year Ended December 30, 2017 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 1,238,258 $ — $ — $ 1,238,258 Brass rod and forgings — 461,603 — 461,603 OEM components, tube & assemblies 94,383 51,707 131,448 277,538 Valves and plumbing specialties 232,309 — — 232,309 Other — 88,821 — 88,821 $ 1,564,950 $ 602,131 $ 131,448 $ 2,298,529 Intersegment sales (32,456 ) Net sales $ 2,266,073 Disaggregation of revenue from contracts with customers (continued): For the Year Ended December 31, 2016 (In thousands) Piping Systems Industrial Metals Climate Total Tube and fittings $ 1,045,031 $ — $ — $ 1,045,031 Brass rod and forgings — 369,363 — 369,363 OEM components, tube & assemblies 145,017 69,578 119,758 334,353 Valves and plumbing specialties 239,541 — — 239,541 Other — 82,119 — 82,119 $ 1,429,589 $ 521,060 $ 119,758 $ 2,070,407 Intersegment sales (14,785 ) Net sales $ 2,055,622
Geographic information	Summarized geographic information is as follows: (In thousands) 2018 2017 2016 Net sales: United States $ 1,820,857 $ 1,556,825 $ 1,400,893 United Kingdom 245,458 231,039 197,039 Canada 292,798 280,140 237,162 Asia 59,730 121,295 149,875 Mexico 89,035 76,774 70,653 $ 2,507,878 $ 2,266,073 $ 2,055,622 (In thousands) 2018 2017 2016 Long-lived assets: United States $ 295,735 $ 238,752 $ 223,099 United Kingdom 16,313 17,661 15,978 Canada 33,144 21,327 18,928 Asia 24,930 25,973 36,722 Mexico 511 608 504 $ 370,633 $ 304,321 $ 295,231
Summary of segment information	Summarized segment information is as follows: For the Year Ended December 29, 2018 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 1,645,633 $ 651,061 $ 229,069 $ (17,885 ) $ 2,507,878 Cost of goods sold 1,426,729 559,367 182,456 (18,152 ) 2,150,400 Depreciation and amortization 23,304 7,568 5,569 3,114 39,555 Selling, general, and administrative expense 74,864 13,501 16,926 43,597 148,888 (Gain) loss on sale of assets (2,093 ) (1,301 ) — 3,141 (253 ) Insurance recovery — (3,681 ) — — (3,681 ) Operating income 122,829 75,607 24,118 (49,585 ) 172,969 Interest expense (25,199 ) Environmental expense (1,320 ) Other income, net 3,967 Income before income taxes $ 150,417 For the Year Ended December 30, 2017 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 1,564,950 $ 602,131 $ 131,448 $ (32,456 ) $ 2,266,073 Cost of goods sold 1,369,161 506,973 98,851 (34,368 ) 1,940,617 Depreciation and amortization 21,777 7,516 2,513 2,138 33,944 Selling, general, and administrative expense 74,441 13,278 9,759 43,252 140,730 Gain on sale of assets (1,491 ) — — — (1,491 ) Impairment charges 1,466 — — — 1,466 Operating income 99,596 74,364 20,325 (43,478 ) 150,807 Interest expense (19,502 ) Environmental expense (7,284 ) Other income, net 2,951 Income before income taxes $ 126,972 Segment information (continued): For the Year Ended December 31, 2016 (In thousands) Piping Systems Industrial Metals Climate Corporate and Eliminations Total Net sales $ 1,429,589 $ 521,060 $ 119,758 $ (14,785 ) $ 2,055,622 Cost of goods sold 1,228,949 420,905 89,927 (16,282 ) 1,723,499 Depreciation and amortization 22,421 8,162 2,437 2,113 35,133 Selling, general, and administrative expense 67,178 13,943 9,661 45,029 135,811 Impairment charges 6,115 663 — — 6,778 Operating income 104,926 77,387 17,733 (45,645 ) 154,401 Interest expense (7,387 ) Environmental expense (1,279 ) Other income, net 295 Income before income taxes $ 146,030
Segment information by assets	(In thousands) 2018 2017 2016 Expenditures for long-lived assets (including those resulting from business acquisitions): Piping Systems $ 31,362 $ 18,124 $ 56,286 Industrial Metals 8,066 5,322 3,302 Climate 85,471 2,191 2,045 General Corporate 37 22,518 55 $ 124,936 $ 48,155 $ 61,688 Segment assets: Piping Systems $ 818,303 $ 801,468 $ 826,663 Industrial Metals 173,725 212,638 160,478 Climate 246,851 73,458 66,968 General Corporate 130,670 232,609 393,367 $ 1,369,549 $ 1,320,173 $ 1,447,476

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 29, 2018
Inventory Disclosure [Abstract]
Inventories	(In thousands) 2018 2017 Raw materials and supplies $ 89,641 $ 108,397 Work-in-process 58,643 46,158 Finished goods 188,506 180,143 Valuation reserves (6,995 ) (6,797 ) Inventories $ 329,795 $ 327,901

Consolidated Financial Statem_2

Consolidated Financial Statement Details (Tables)	12 Months Ended
	Dec. 29, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Other (expense) income, net	Other Income, Net (In thousands) 2018 2017 2016 Net periodic benefit income (cost) $ 2,914 $ 1,150 $ (1,687 ) Interest income 624 684 1,185 Other 429 1,117 797 Other income, net $ 3,967 $ 2,951 $ 295

Derivative Instruments and He_2

Derivative Instruments and Hedging Activities (Tables)	12 Months Ended
	Dec. 29, 2018
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 2018 2017 Balance Sheet Location 2018 2017 Commodity contracts - gains Other current assets $ 88 $ 1,014 Other current liabilities $ 103 $ 55 Commodity contracts - losses Other current assets (1 ) (5 ) Other current liabilities (1,382 ) (3,210 ) Total derivatives (1) $ 87 $ 1,009 $ (1,279 ) $ (3,155 ) (1) Does not include the impact of cash collateral provided to counterparties .
Schedule of fair value hedges	The following table summarizes the effects of derivative instruments on the Consolidated Statements of Income: (In thousands) Location 2018 2017 Fair value hedges: Gain (loss) on commodity contracts (qualifying) Cost of goods sold $ 391 $ (724 ) (Loss) gain on hedged item - inventory Cost of goods sold (385 ) 625 Undesignated derivatives: Gain (loss) on commodity contracts (nonqualifying) Cost of goods sold $ 4,227 $ (6,078 )
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: Year Ended December 29, 2018 (In thousands) Loss Recognized in AOCI (Effective Portion), Net of Tax Classification Gains (Losses) Gain Reclassified from AOCI (Effective Portion), Net of Tax Cash flow hedges: Commodity contracts $ (793 ) Cost of goods sold $ (371 ) Other (9 ) Other — Total $ (802 ) Total $ (371 ) Year Ended December 30, 2017 (In thousands) (Loss) Gain 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 $ (574 ) Cost of goods sold $ 990 Interest rate swap — Interest expense 546 Other 185 Other — Total $ (389 ) Total $ 1,536

Property, Plant, and Equipmen_2

Property, Plant, and Equipment, Net (Tables)	12 Months Ended
	Dec. 29, 2018
Property, Plant and Equipment [Abstract]
Property, plant, and equipment, net	(In thousands) 2018 2017 Land and land improvements $ 32,132 $ 18,740 Buildings 201,176 144,527 Machinery and equipment 635,173 649,667 Construction in progress 22,618 9,274 891,099 822,208 Less accumulated depreciation (520,466 ) (517,887 ) Property, plant, and equipment, net $ 370,633 $ 304,321

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 29, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the carrying amount of goodwill	The changes in the carrying amount of goodwill by segment were as follows: (In thousands) Piping Systems Industrial Metals Climate Total Goodwill $ 160,128 $ 8,854 $ 4,416 $ 173,398 Accumulated impairment charges (40,552 ) (8,853 ) — (49,405 ) Balance at December 31, 2016: 119,576 1 4,416 123,993 Additions (1) 3,852 — — 3,852 Currency translation 2,448 — — 2,448 Balance at December 30, 2017: 125,876 1 4,416 130,293 Additions (2) 5,049 — 17,770 22,819 Currency translation (2,777 ) — — (2,777 ) Balance at December 29, 2018: Goodwill 168,700 8,854 22,186 199,740 Accumulated impairment charges (40,552 ) (8,853 ) — (49,405 ) Goodwill, net $ 128,148 $ 1 $ 22,186 $ 150,335 (1) Includes finalization of the purchase price allocation adjustment for Jungwoo-Mueller of $0.2 million . (2) Includes finalization of the purchase price allocation adjustment for Heatlink Group of $2.8 million .
Carrying amount of intangible assets	The carrying amount of intangible assets at December 29, 2018 was as follows: (In thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Customer relationships $ 43,104 $ (6,309 ) $ 36,795 Non-compete agreements 2,400 (1,582 ) 818 Patents and technology 17,879 (2,595 ) 15,284 Trade names and licenses 9,173 (2,188 ) 6,985 Other 2,526 (437 ) 2,089 Other intangible assets $ 75,082 $ (13,111 ) $ 61,971 The carrying amount of intangible assets at December 30, 2017 was as follows: (In thousands) Gross Carrying Amount Accumulated Amortization Net Carrying Amount Customer relationships $ 36,518 $ (4,644 ) $ 31,874 Non-compete agreements 2,834 (1,497 ) 1,337 Patents and technology 7,673 (1,868 ) 5,805 Trade names and licenses 4,977 (1,575 ) 3,402 Other 213 (623 ) (410 ) Other intangible assets $ 52,215 $ (10,207 ) $ 42,008
Amortization expense for intangible assets	Future amortization expense is estimated as follows: (In thousands) Amount 2019 $ 5,242 2020 5,047 2021 4,773 2022 4,693 2023 4,297 Thereafter 37,919 Expected amortization expense $ 61,971

Investment in Unconsolidated _2

Investment in Unconsolidated Affiliates (Tables)	12 Months Ended
	Dec. 29, 2018
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) 2018 2017 Current assets $ 228,214 $ 246,127 Noncurrent assets 114,257 139,200 Current liabilities 175,371 174,710 Noncurrent liabilities 57,216 58,334 Net sales $ 509,517 $ 556,600 Gross profit 59,385 75,600 Net loss (20,049 ) (4,153 )

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 29, 2018
Debt Disclosure [Abstract]
Schedule of Debt	(In thousands) 2018 2017 Subordinated Debentures with interest at 6.00%, due 2027 $ 284,479 $ 284,536 Revolving Credit Facility with interest at 3.97%, due 2021 195,000 160,000 Jungwoo-Mueller credit facility with interest at 2.86%, due 2019 5,264 5,119 Jungwoo-Mueller credit facility with interest at 3.45%, due 2020 5,104 8,648 2001 Series IRB's with interest at 3.22%, due 2021 2,250 3,250 Other 5,458 4,694 497,555 466,247 Less debt issuance costs (857 ) (1,175 ) Less current portion of debt (7,101 ) (16,480 ) Long-term debt $ 489,597 $ 448,592
Debt instrument redemption	If redeemed during the 12-month period beginning March 9: Year Redemption Price 2018 105% 2019 104 2020 103 2021 102 2022 and thereafter 100
Aggregate annual maturities of debt	Aggregate annual maturities of the Company’s debt are as follows: (In thousands) Amount 2019 $ 7,101 2020 6,831 2021 195,955 2022 618 2023 402 Thereafter 286,648 Long-term debt $ 497,555
Net interest expense	Net interest expense consisted of the following: (In thousands) 2018 2017 2016 Interest expense $ 25,349 $ 19,716 $ 7,749 Capitalized interest (150 ) (214 ) (362 ) $ 25,199 $ 19,502 $ 7,387

Benefit Plans (Tables)

Benefit Plans (Tables)	12 Months Ended
	Dec. 29, 2018
Retirement Benefits [Abstract]
Reconciliation of the changes in the plans' benefit obligations and the fair value of the plans assets	The following tables provide a reconciliation of the changes in the plans’ benefit obligations and the fair value of the plans’ assets for 2018 and 2017 , and a statement of the plans’ aggregate funded status: Pension Benefits Other Benefits (In thousands) 2018 2017 2018 2017 Change in benefit obligation: Obligation at beginning of year $ 186,766 $ 178,736 $ 16,407 $ 15,274 Service cost 88 128 235 235 Interest cost 5,745 6,344 447 599 Actuarial (gain) loss (10,637 ) 4,688 (1,185 ) 923 Benefit payments (10,368 ) (10,171 ) (892 ) (883 ) Settlement charge — — (171 ) (209 ) Foreign currency translation adjustment (4,855 ) 7,041 (459 ) 468 Obligation at end of year 166,739 186,766 14,382 16,407 Change in fair value of plan assets: Fair value of plan assets at beginning of year 186,336 169,140 — — Actual return on plan assets (8,282 ) 19,175 — — Employer contributions 999 2,271 892 883 Benefit payments (10,368 ) (10,171 ) (892 ) (883 ) Foreign currency translation adjustment (4,082 ) 5,921 — — Fair value of plan assets at end of year 164,603 186,336 — — Underfunded status at end of year $ (2,136 ) $ (430 ) $ (14,382 ) $ (16,407 )
Amounts recognized in accumulated OCI (before the effect of income taxes)	The following represents amounts recognized in AOCI (before the effect of income taxes): Pension Benefits Other Benefits (In thousands) 2018 2017 2018 2017 Unrecognized net actuarial loss $ 39,101 $ 34,627 $ 170 $ 1,540 Unrecognized prior service credit — — (6,387 ) (7,289 )
Funded status of the plans recognized	As of December 29, 2018 and December 30, 2017 , the total funded status of the plans recognized in the Consolidated Balance Sheets was as follows: Pension Benefits Other Benefits (In thousands) 2018 2017 2018 2017 Long-term asset $ 10,580 $ 9,894 $ — $ — Current liability — — (1,080 ) (1,070 ) Long-term liability (12,716 ) (10,324 ) (13,302 ) (15,337 ) Total underfunded status $ (2,136 ) $ (430 ) $ (14,382 ) $ (16,407 )
Components of net periodic benefit costs	The components of net periodic benefit cost (income) are as follows: (In thousands) 2018 2017 2016 Pension benefits: Service cost $ 88 $ 128 $ 532 Interest cost 5,745 6,344 7,553 Expected return on plan assets (9,522 ) (9,374 ) (9,615 ) Amortization of net loss 1,151 2,206 2,898 Settlement charge — — 1,214 Net periodic benefit (income) cost $ (2,538 ) $ (696 ) $ 2,582 Other benefits: Service cost $ 235 $ 235 $ 232 Interest cost 447 599 594 Amortization of prior service credit (902 ) (901 ) (896 ) Amortization of net loss (gain) 92 (42 ) (60 ) Settlement charge 38 17 — Net periodic benefit income $ (90 ) $ (92 ) $ (130 )
Weighted average assumptions used in the measurement of the Company's benefit obligation and net periodic benefit cost are as follows	The weighted average assumptions used in the measurement of the Company’s benefit obligations are as follows: Pension Benefits Other Benefits 2018 2017 2018 2017 Discount rate 3.72 % 3.22 % 4.56 % 3.89 % Expected long-term return on plan assets 5.05 % 5.27 % N/A N/A Rate of compensation increases N/A N/A 5.00 % 5.00 % Rate of inflation 3.40 % 3.30 % N/A N/A The weighted average assumptions used in the measurement of the Company’s net periodic benefit cost are as follows: Pension Benefits Other Benefits 2018 2017 2016 2018 2017 2016 Discount rate 3.22 % 3.61 % 4.02 % 3.89 % 4.21 % 4.25 % Expected long-term return on plan assets 5.27 % 5.56 % 5.59 % N/A N/A N/A Rate of compensation increases N/A N/A N/A 5.00 % 5.00 % 5.00 % Rate of inflation 3.30 % 3.30 % 3.20 % N/A N/A N/A
Weighted average asset allocation of the Company’s pension fund assets are as follows	The weighted average asset allocation of the Company’s pension fund assets are as follows: Pension Plan Assets Asset category 2018 2017 Fixed income securities (includes fixed income mutual funds) 54 % 48 % Equity securities (includes equity mutual funds) 35 46 Cash and equivalents (includes money market funds) 8 3 Alternative investments 3 3 Total 100 % 100 %
Plan assets at fair value within the fair value hierarchy, by level	The following table sets forth by level, within the fair value hierarchy, the assets of the plans at fair value: Fair Value Measurements at December 29, 2018 (In thousands) Level 1 Level 2 Level 3 Total Cash and money market funds $ 12,984 $ — $ — $ 12,984 Mutual funds (1) — 146,591 — 146,591 Limited partnerships — — 5,028 5,028 Total $ 12,984 $ 146,591 $ 5,028 $ 164,603 Fair Value Measurements at December 30, 2017 (In thousands) Level 1 Level 2 Level 3 Total Cash and money market funds $ 5,364 $ — $ — $ 5,364 Common stock (2) 11,113 — — 11,113 Mutual funds (3) 8,412 156,442 — 164,854 Limited partnerships — — 5,005 5,005 Total $ 24,889 $ 156,442 $ 5,005 $ 186,336 (1) Approximately 61 percent of mutual funds are actively managed funds and approximately 39 percent of mutual funds are index funds. Additionally, five percent of the mutual funds’ assets are invested in U.S. equities, 35 percent in non-U.S. equities, 59 percent in U.S. fixed income securities, and one percent in non-U.S. fixed income securities. (2) Approximately 91 percent of common stock represents investments in U.S. companies primarily in the health care, utilities, financials, consumer staples, industrials, and information technology sectors. All investments in common stock are listed on U.S. stock exchanges. (3) Approximately 66 percent of mutual funds are actively managed funds and approximately 34 percent of mutual funds are index funds. Additionally, five percent of the mutual funds’ assets are invested in U.S. equities, 41 percent in non-U.S. equities, 52 percent in U.S. fixed income securities, and two percent in non-U.S. fixed income securities.
Plan assets measured at fair value using significant unobservable inputs	The table below reflects the changes in the assets of the plan measured at fair value on a recurring basis using significant unobservable inputs (level 3 of fair value hierarchy) during the year ended December 29, 2018 : (In thousands) Limited Partnerships Balance, December 30, 2017 $ 5,005 Redemptions (108 ) Subscriptions 108 Net appreciation in fair value 23 Balance, December 29, 2018 $ 5,028
Future benefit plans payments	The Company expects future benefits to be paid from the plans as follows: (In thousands) Pension Benefits Other Benefits 2019 $ 10,416 $ 1,102 2020 10,342 1,244 2021 10,283 1,061 2022 10,241 1,112 2023 10,196 1,226 2024-2028 49,820 5,821 Total $ 101,298 $ 11,566

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 29, 2018
Income Tax Disclosure [Abstract]
Components of income before income taxes	The components of income before income taxes were taxed under the following jurisdictions: (In thousands) 2018 2017 2016 Domestic $ 105,455 $ 76,876 $ 103,576 Foreign 44,962 50,096 42,454 Income before income taxes $ 150,417 $ 126,972 $ 146,030
Components of income tax expense	Income tax expense consists of the following: (In thousands) 2018 2017 2016 Current tax expense: Federal $ 17,974 $ 28,584 $ 32,262 Foreign 9,650 10,219 5,667 State and local 3,158 2,241 3,210 Current tax expense 30,782 41,044 41,139 Deferred tax expense (benefit): Federal (1,381 ) (1,764 ) 2,004 Foreign 551 1,118 5,099 State and local 1,000 (2,514 ) (105 ) Deferred tax expense (benefit) 170 (3,160 ) 6,998 Income tax expense $ 30,952 $ 37,884 $ 48,137
Income tax reconciliation	The difference between the reported income tax expense and a tax determined by applying the applicable U.S. federal statutory income tax rate to income before income taxes is reconciled as follows: (In thousands) 2018 2017 2016 Expected income tax expense $ 31,588 $ 44,440 $ 51,110 State and local income tax, net of federal benefit 3,495 1,135 1,982 Effect of foreign statutory rates different from U.S. and other foreign adjustments 759 (6,026 ) (4,092 ) Changes in valuation allowances 1,133 — — U.S. production activities deduction — (1,575 ) (3,063 ) Investment in unconsolidated affiliates (3,909 ) 216 1,030 Benefit of stock-based compensation deductions (41 ) (2,160 ) (656 ) Effect of tax on accumulated foreign earnings (4,415 ) 12,893 — Effect of tax rate change on net deferred tax liability balance — (12,067 ) — Other, net 2,342 1,028 1,826 Income tax expense $ 30,952 $ 37,884 $ 48,137
Components of deferred tax assets and liabilities	The tax effects of temporary differences that give rise to significant portions of the deferred tax assets and deferred tax liabilities are presented below: (In thousands) 2018 2017 Deferred tax assets: Inventories $ 12,297 $ 10,598 Other postretirement benefits and accrued items 9,213 9,239 Other reserves 7,847 9,029 Federal and foreign tax attributes 6,252 11,936 State tax attributes, net of federal benefit 27,651 29,720 Stock-based compensation 2,949 2,102 Basis difference in unconsolidated affiliates 1,067 — Total deferred tax assets 67,276 72,624 Less valuation allowance (25,311 ) (30,316 ) Deferred tax assets, net of valuation allowance 41,965 42,308 Deferred tax liabilities: Property, plant, and equipment 44,910 43,972 Pension 250 3,841 Basis difference in unconsolidated affiliates — 203 Total deferred tax liabilities 45,160 48,016 Net deferred tax liabilities $ (3,195 ) $ (5,708 )

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 29, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Weighted average assumptions used in calculating fair value of stock options	The weighted average of key assumptions used in determining the fair value of options granted and a discussion of the methodology used to develop each assumption are as follows: 2018 2017 2016 Expected term 7.6 years 7.7 years 6.7 years Expected price volatility 27.2 % 28.9 % 25.6 % Risk-free interest rate 2.9 % 2.1 % 1.6 % Dividend yield 1.3 % 1.3 % 1.0 %
Summary of the stock option activity	A summary of the activity and related information follows: Stock Options Restricted Stock Awards (Shares in thousands) Shares Weighted Average Exercise Price Shares Weighted Average Grant Date Fair Value Outstanding at December 30, 2017 947 $ 22.31 781 $ 31.83 Granted 142 31.33 276 32.04 Exercised/Released (57 ) 15.10 (124 ) 29.95 Forfeited (18 ) 26.78 (3 ) 32.60 Outstanding at December 29, 2018 1,014 23.90 930 32.14

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Income (Loss) (Tables)	12 Months Ended
	Dec. 29, 2018
Equity [Abstract]
Changes in AOCI by component, net of taxes and noncontrolling interest	The following table provides changes in AOCI by component, net of taxes and noncontrolling interest (amounts in parentheses indicate debits to AOCI): (In thousands) Cumulative Translation Adjustment Unrealized (Loss) Gain on Derivatives Pension/ Unrealized Gain (Loss) on Equity Securities Attributable to Unconsol. Affiliates Total Balance at December 31, 2016 $ (49,965 ) $ (300 ) $ (23,046 ) $ 380 $ 5,975 $ (66,956 ) Other comprehensive income (loss) before reclassifications 15,579 (389 ) 1,394 (1 ) 895 17,478 Amounts reclassified from AOCI (3,777 ) 1,536 1,042 (379 ) — (1,578 ) Balance at December 30, 2017 (38,163 ) 847 (20,610 ) — 6,870 (51,056 ) Other comprehensive loss before reclassifications (16,094 ) (802 ) (3,642 ) — (8,686 ) (29,224 ) Amounts reclassified from AOCI — (371 ) 303 — — (68 ) Net current-period other comprehensive loss (16,094 ) (1,173 ) (3,339 ) — (8,686 ) (29,292 ) Reclassification of stranded effects of the Act — 112 (1,018 ) — 1,462 556 Balance at December 29, 2018 $ (54,257 ) $ (214 ) $ (24,967 ) $ — $ (354 ) $ (79,792 )
Reclassification adjustments out of AOCI	Reclassification adjustments out of AOCI were as follows: Amount reclassified from AOCI (In thousands) 2018 2017 2016 Affected Line Item Unrealized losses (gains) on derivatives: Commodity contracts $ (429 ) $ 1,309 $ 1,061 Cost of goods sold Interest rate swap — 851 361 Interest expense 58 (624 ) (113 ) Income tax expense (benefit) $ (371 ) $ 1,536 $ 1,309 Net of tax and noncontrolling interests Amortization of net loss and prior service cost on employee benefit plans $ 341 $ 1,263 $ 1,942 Other income, net (38 ) (221 ) (521 ) Income tax benefit $ 303 $ 1,042 $ 1,421 Net of tax and noncontrolling interests Gain recognized upon sale of business $ — $ (3,777 ) $ — Gain on sale of assets — — — Income tax expense $ — $ (3,777 ) $ — Net of tax and noncontrolling interests Sale of available-for-sale securities $ — $ (611 ) $ — Other income, net — 232 — Income tax expense $ — $ (379 ) $ — Net of tax and noncontrolling interests

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 29, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly financial information (Unaudited)	(In thousands, except per share data) First Quarter Second Quarter Third Quarter Fourth Quarter 2018 Net sales $ 640,060 $ 662,773 $ 645,958 $ 559,087 Gross profit (2) 94,390 98,953 79,002 85,133 Consolidated net income (3) 24,344 33,882 20,863 27,731 Net income attributable to Mueller Industries, Inc. 24,128 33,182 20,292 26,857 Basic earnings per share 0.42 0.58 0.36 0.47 Diluted earnings per share 0.42 0.58 0.35 0.47 Dividends per share 0.10 0.10 0.10 0.10 2017 Net sales $ 577,920 $ 614,266 $ 550,363 $ 523,524 Gross profit (2) 89,493 89,955 79,101 66,907 Consolidated net income (4) 30,455 27,833 22,754 5,969 (5) Net income attributable to Mueller Industries, Inc. 29,987 27,633 22,258 5,720 Basic earnings per share 0.53 0.49 0.39 0.10 Diluted earnings per share 0.52 0.48 0.39 0.10 Dividends per share 8.10 0.10 0.10 0.10 (1) The sum of quarterly amounts may not equal the annual amounts reported due to rounding. In addition, the earnings per share amounts are computed independently for each quarter, while the full year is based on the weighted average shares outstanding. (2) Gross profit is net sales less cost of goods sold, which excludes depreciation and amortization. (3) Includes income earned by ATCO, acquired during Q3 2018, and Die-Mold, acquired during Q1 2018. (4) Includes income earned by Heatlink Group, acquired during Q2 2017. (5) Includes $1.1 million of pre-tax charges related to asset impairments, $4.3 million of interest expense on the Company’s Subordinated Debentures, and pre-tax environmental expense for non-operating properties of $6.2 million .

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Jan. 01, 2019
Noncontrolling Interest [Line Items]
Temporary investments		$ 600	$ 600
Restricted cash		$ 4,400	$ 6,200
Specified percentage over which unrecognized gains and losses are amortized		10.00%
Average remaining service period for the pension plans		9 years
Stock-based awards excluded from the computation of diluted earnings per share (in shares)		54	20
Foreign currency transaction gains (losses)		$ (1,000)	$ (400)	$ 400
Net periodic benefit (income) cost		(2,914)	(1,150)	1,687
Future minimum lease payments under operating lease		$ 38,300	40,500
Tecumseh Products Holdings LLC [Member]
Noncontrolling Interest [Line Items]
Equity method investment, ownership percentage		50.00%
Second Unconsolidated Affiliate [Member]
Noncontrolling Interest [Line Items]
Equity method investment, ownership percentage		50.00%
Mueller Middle East BSC [Member]
Noncontrolling Interest [Line Items]
Equity method investment, ownership percentage		40.00%
Building [Member] | Minimum [Member]
Noncontrolling Interest [Line Items]
Property, plant and equipment, useful life		20 years
Building [Member] | Maximum [Member]
Noncontrolling Interest [Line Items]
Property, plant and equipment, useful life		40 years
Machinery and Equipment [Member] | Minimum [Member]
Noncontrolling Interest [Line Items]
Property, plant and equipment, useful life		5 years
Machinery and Equipment [Member] | Maximum [Member]
Noncontrolling Interest [Line Items]
Property, plant and equipment, useful life		20 years
Mueller-Xingrong [Member]
Noncontrolling Interest [Line Items]
Non-controlling ownership interest		49.50%
Jungwoo-Mueller [Member]
Noncontrolling Interest [Line Items]
Non-controlling ownership interest		40.00%
Other Nonoperating Income (Expense) [Member]
Noncontrolling Interest [Line Items]
Net periodic benefit (income) cost			(1,200)	(1,700)
Accounting Standards Update 2018-02 [Member]
Noncontrolling Interest [Line Items]
Reclassification of stranded effects of the Act	$ 556
Accounting Standards Update 2017-07 [Member] | Operating Income (Loss) [Member]
Noncontrolling Interest [Line Items]
Net periodic benefit (income) cost			(1,200)	1,700
Accounting Standards Update 2016-18 [Member]
Noncontrolling Interest [Line Items]
Increase in cash, cash equivalents and restricted cash			$ 6,300	$ 9,200
Subsequent Event [Member] | Scenario, Forecast [Member] | Accounting Standards Update 2018-10 [Member] | Minimum [Member]
Noncontrolling Interest [Line Items]
Right-of-Use asset					$ 25,000
Lease liability					25,000
Subsequent Event [Member] | Scenario, Forecast [Member] | Accounting Standards Update 2018-10 [Member] | Maximum [Member]
Noncontrolling Interest [Line Items]
Right-of-Use asset					35,000
Lease liability					$ 30,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Reconciliation of Cash Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016	[1]	Dec. 26, 2015	[1]
Accounting Policies [Abstract]
Cash and cash equivalents	$ 72,616	$ 120,269
Restricted cash included within other current assets	4,414	6,189
Restricted cash included within other assets	108	105
Total cash, cash equivalents, and restricted cash	$ 77,138	$ 126,563	[1]	$ 360,469		$ 278,664
[1]	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.

Acquisitions and Dispositions -

Acquisitions and Dispositions - Acquisitions Narrative (Details) - USD ($) $ in Thousands	Jul. 02, 2018	Mar. 31, 2018	May 31, 2017	Apr. 26, 2016	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016	[1]
Business Acquisition [Line Items]
Cash paid for acquisition					$ 167,677	$ 18,396	[1]	$ 20,533
ATCO Rubber Product [Member]
Business Acquisition [Line Items]
Total consideration paid	$ 156,704
Cash paid for acquisition	151,400
Contingent consideration, range of outcomes, high	12,000
Revenues of acquired company	166,000				$ 90,000
Deferred tax liability recognized	$ 0
Die-Mold [Member]
Business Acquisition [Line Items]
Net assets acquired		$ 13,629
Total consideration paid		13,629
Cash paid for acquisition		12,400
Contingent consideration, range of outcomes, high		2,300
Deferred tax liability recognized		$ 0
Heatlink Group [Member]
Business Acquisition [Line Items]
Net assets acquired			$ 17,164
Total consideration paid			17,164
Contingent consideration, range of outcomes, high			2,200
Cash paid for acquisition			16,300
Contingent consideration liability						$ 900
Deferred tax liability recognized			$ 1,891
Jungwoo-Mueller [Member]
Business Acquisition [Line Items]
Net assets acquired				$ 20,533
Total consideration paid				20,533
Cash paid for acquisition				$ 20,500
Equity method investment, ownership percentage				60.00%
Deferred tax liability recognized				$ 582
[1]	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.

Acquisitions and Dispositions_2

Acquisitions and Dispositions - Pro Forma Information (Details) - ATCO Rubber Product [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Business Acquisition [Line Items]
Net sales	$ 2,595,454	$ 2,431,972
Net income	$ 111,482	$ 90,270
Basic earnings per share (in dollars per share)	$ 1.96	$ 1.59
Diluted earnings per share (in dollars per share)	$ 1.95	$ 1.57

Acquisitions and Dispositions_3

Acquisitions and Dispositions - Schedule of Recognized Identifiable Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Jul. 02, 2018	Mar. 31, 2018	May 31, 2017	Apr. 26, 2016	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016	Jul. 31, 2015	Mar. 30, 2015	Feb. 28, 2014
Business Acquisition [Line Items]
Goodwill					$ 150,335	$ 130,293	$ 123,993
Noncontrolling interests					$ 14,904	$ 13,917
ATCO Rubber Product [Member]
Business Acquisition [Line Items]
Total consideration	$ 156,704
Accounts receivable	21,829
Inventories	31,666
Other current assets	1,051
Property, plant, and equipment	83,080
Goodwill	17,770
Intangible assets	21,430			$ 21,430
Other assets	224
Total assets acquired	177,050
Accounts payable	8,093
Other current liabilities	10,187
Long-term debt	2,066
Pension and other postretirement liabilities	0
Other noncurrent liabilities	0
Total liabilities assumed	20,346
Noncontrolling interests	$ 0
Die-Mold [Member]
Business Acquisition [Line Items]
Total consideration		$ 13,629
Accounts receivable		1,684
Inventories		1,833
Other current assets		267
Property, plant, and equipment		3,278
Goodwill		2,241
Intangible assets		5,209						$ 5,209
Other assets		0
Total assets acquired		14,512
Accounts payable		710
Other current liabilities		173
Long-term debt		0
Pension and other postretirement liabilities		0
Other noncurrent liabilities		0
Total liabilities assumed		883
Noncontrolling interests		0
Net assets acquired		$ 13,629
Heatlink Group [Member]
Business Acquisition [Line Items]
Total consideration			$ 17,164
Accounts receivable			2,809
Inventories			4,648
Other current assets			508
Property, plant, and equipment			2,024
Goodwill			6,879
Intangible assets			6,413						$ 6,413
Other assets			0
Total assets acquired			23,281
Accounts payable			3,633
Other current liabilities			593
Long-term debt			0
Pension and other postretirement liabilities			0
Other noncurrent liabilities			1,891
Total liabilities assumed			6,117
Noncontrolling interests			0
Net assets acquired			$ 17,164
Jungwoo-Mueller [Member]
Business Acquisition [Line Items]
Total consideration				20,533
Accounts receivable				5,551
Inventories				17,616
Other current assets				1,437
Property, plant, and equipment				24,191
Goodwill				223
Intangible assets				756						$ 756
Other assets				277
Total assets acquired				50,051
Accounts payable				7,252
Other current liabilities				577
Long-term debt				8,659
Pension and other postretirement liabilities				799
Other noncurrent liabilities				582
Total liabilities assumed				17,869
Noncontrolling interests				11,649
Net assets acquired				$ 20,533

Acquisitions and Dispositions_4

Acquisitions and Dispositions - Schedule of Intangible Assets Identified (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Jul. 02, 2018	Mar. 31, 2018	May 31, 2017	Apr. 26, 2016	Jul. 31, 2015	Mar. 30, 2015	Feb. 28, 2014
ATCO Rubber Product [Member]
Business Acquisition [Line Items]
Intangible assets		$ 21,430			$ 21,430
Die-Mold [Member]
Business Acquisition [Line Items]
Intangible assets			$ 5,209			$ 5,209
Heatlink Group [Member]
Business Acquisition [Line Items]
Intangible assets				$ 6,413			$ 6,413
Jungwoo-Mueller [Member]
Business Acquisition [Line Items]
Intangible assets					756			$ 756
Customer Relationships [Member]
Business Acquisition [Line Items]
Intangible assets, useful life	20 years
Customer Relationships [Member] | ATCO Rubber Product [Member]
Business Acquisition [Line Items]
Intangible assets					6,200
Customer Relationships [Member] | Die-Mold [Member]
Business Acquisition [Line Items]
Intangible assets						3,077
Customer Relationships [Member] | Heatlink Group [Member]
Business Acquisition [Line Items]
Intangible assets							4,265
Customer Relationships [Member] | Jungwoo-Mueller [Member]
Business Acquisition [Line Items]
Intangible assets								0
Noncompete Agreements [Member] | ATCO Rubber Product [Member]
Business Acquisition [Line Items]
Intangible assets					0
Noncompete Agreements [Member] | Die-Mold [Member]
Business Acquisition [Line Items]
Intangible assets						70
Noncompete Agreements [Member] | Heatlink Group [Member]
Business Acquisition [Line Items]
Intangible assets							74
Noncompete Agreements [Member] | Jungwoo-Mueller [Member]
Business Acquisition [Line Items]
Intangible assets								0
Patents and technology [Member] | ATCO Rubber Product [Member]
Business Acquisition [Line Items]
Intangible assets					8,950
Patents and technology [Member] | Die-Mold [Member]
Business Acquisition [Line Items]
Intangible assets						1,512
Patents and technology [Member] | Heatlink Group [Member]
Business Acquisition [Line Items]
Intangible assets							1,466
Patents and technology [Member] | Jungwoo-Mueller [Member]
Business Acquisition [Line Items]
Intangible assets								756
Trade names and licenses [Member] | ATCO Rubber Product [Member]
Business Acquisition [Line Items]
Intangible assets					3,960
Trade names and licenses [Member] | Die-Mold [Member]
Business Acquisition [Line Items]
Intangible assets						550
Trade names and licenses [Member] | Heatlink Group [Member]
Business Acquisition [Line Items]
Intangible assets							608
Trade names and licenses [Member] | Jungwoo-Mueller [Member]
Business Acquisition [Line Items]
Intangible assets								0
Supply Contracts [Member]
Business Acquisition [Line Items]
Intangible assets, useful life	5 years
Supply Contracts [Member] | ATCO Rubber Product [Member]
Business Acquisition [Line Items]
Intangible assets					$ 2,320
Supply Contracts [Member] | Die-Mold [Member]
Business Acquisition [Line Items]
Intangible assets						$ 0
Supply Contracts [Member] | Heatlink Group [Member]
Business Acquisition [Line Items]
Intangible assets							$ 0
Supply Contracts [Member] | Jungwoo-Mueller [Member]
Business Acquisition [Line Items]
Intangible assets								$ 0
Maximum [Member] | Noncompete Agreements [Member]
Business Acquisition [Line Items]
Intangible assets, useful life	5 years
Maximum [Member] | Patents and technology [Member]
Business Acquisition [Line Items]
Intangible assets, useful life	15 years
Maximum [Member] | Trade names and licenses [Member]
Business Acquisition [Line Items]
Intangible assets, useful life	10 years
Minimum [Member] | Noncompete Agreements [Member]
Business Acquisition [Line Items]
Intangible assets, useful life	3 years
Minimum [Member] | Patents and technology [Member]
Business Acquisition [Line Items]
Intangible assets, useful life	10 years
Minimum [Member] | Trade names and licenses [Member]
Business Acquisition [Line Items]
Intangible assets, useful life	5 years

Acquisitions and Dispositions_5

Acquisitions and Dispositions - Dispositions Narrative (Details) - USD ($) $ in Thousands	Jun. 21, 2017	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net loss		$ (20,049)	$ (4,153)
Gain on sale of business		$ 0	1,491	$ 0
Mueller-Xingrong [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Equity method investment, ownership percentage	50.50%
Net sales of equity method investment			67,300	121,500
Net loss			(9)	$ 62
Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] | Mueller-Xingrong [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of interest	$ 18,300
Assets	56,800
Carrying value of the liabilities disposed	36,200
Cumulative translation loss	$ 3,800
Gain on sale of business			$ 1,500

Segment Information - Narrative

Segment Information - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 30, 2017	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016
Revenue from External Customer [Line Items]
Gain on sale of manufacturing equipment		$ 253	$ 624	[1]	$ 651	[1]
Gain on sale of business		0	(1,491)		0
Impairment charges	$ 1,100	0	1,466	[1],[2]	6,778	[1],[2]
Insurance recovery		(3,681)	0	[2]	0	[2]
Gain on sale of assets, net		(253)	(1,491)	[1],[2]	0	[1],[2]
Operating Segments [Member] | Piping Systems [Member]
Revenue from External Customer [Line Items]
Gain on sale of real property		1,400
Gain on sale of manufacturing equipment		700
Gain on sale of business			(1,500)
Impairment charges			1,466		6,115
Insurance recovery		0
Gain on sale of assets, net		(2,093)	(1,491)
Operating Segments [Member] | Industrial Metals [Member]
Revenue from External Customer [Line Items]
Impairment charges			0		$ 663
Insurance recovery		(3,681)
Gain on sale of assets, net		$ (1,301)	$ 0
[1]	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.
[2]	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.

Segment Information - Summary o

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.

Segment Information - Schedule

Segment Information - Schedule of Geographic 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
Revenues from External Customers and Long-Lived Assets [Line Items]
Gain on sale of assets, net									$ (253)	$ (1,491)	[1],[2]	$ 0	[1],[2]
Net sales	$ 559,087	$ 645,958	$ 662,773	$ 640,060	$ 523,524	$ 550,363	$ 614,266	$ 577,920	2,507,878	2,266,073	[2]	2,055,622	[2]
Long-lived assets	370,633				304,321				370,633	304,321		295,231
Reportable Geographical Components [Member] | United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									1,820,857	1,556,825		1,400,893
Long-lived assets	295,735				238,752				295,735	238,752		223,099
Reportable Geographical Components [Member] | United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									245,458	231,039		197,039
Long-lived assets	16,313				17,661				16,313	17,661		15,978
Reportable Geographical Components [Member] | Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									292,798	280,140		237,162
Long-lived assets	33,144				21,327				33,144	21,327		18,928
Reportable Geographical Components [Member] | Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									59,730	121,295		149,875
Long-lived assets	24,930				25,973				24,930	25,973		36,722
Reportable Geographical Components [Member] | Mexico [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net sales									89,035	76,774		70,653
Long-lived assets	$ 511				$ 608				$ 511	$ 608		$ 504
[1]	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.
[2]	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.

Inventories - Schedule of Inven

Inventories - Schedule of Inventories (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Inventory Disclosure [Abstract]
Raw materials and supplies	$ 89,641	$ 108,397
Work-in-process	58,643	46,158
Finished goods	188,506	180,143
Valuation reserves	(6,995)	(6,797)
Inventories	$ 329,795	$ 327,901

Inventories - Narrative (Detail

Inventories - Narrative (Details) - USD ($) $ in Millions	Dec. 29, 2018	Dec. 30, 2017
Inventory Disclosure [Abstract]
LIFO inventory amount	$ 18.8	$ 26.5
FIFO cost of inventories	91.8	111
Average cost basis inventories	53.6	43.9
FIFO value of inventory consigned to others	$ 5.1	$ 4.4

Consolidated Financial Statem_3

Consolidated Financial Statement Details (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 30, 2017	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016
Other Current Liabilities [Abstract]
Accrued discounts and allowances	$ 39,500	$ 48,600	$ 39,500
Taxes payable, current	9,200	5,000	9,200
Accrued interest	5,900	5,800	5,900
Environmental expense, non operating properties	$ 6,200	3,600	4,300
Other (Expense) Income, Net [Abstract]
Net periodic benefit income (cost)		2,914	1,150		$ (1,687)
Interest income		624	684		1,185
Other		429	1,117		797
Other income, net		$ 3,967	$ 2,951	[1]	$ 295	[1]
[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.

Derivative Instruments and He_3

Derivative Instruments and Hedging Activities - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Derivative [Line Items]
Restricted cash in other current assets as collateral related to open derivative contracts	$ 3.6	$ 5.3
Commodity Contract [Member]
Derivative [Line Items]
Deferred net gains (losses), net of tax, included in AOCI	(0.4)
Cash Flow Hedging [Member] | Commodity Contract [Member] | Long [Member]
Derivative [Line Items]
Open future contracts to purchase copper	$ 59.4
Time period for open copper future contract	12 months
Fair value of future contracts with gain (loss) position	$ (1.3)
Fair Value Hedging [Member] | Commodity Contract [Member] | Short [Member]
Derivative [Line Items]
Fair value of future contracts with gain (loss) position	0.1
Open future contracts to sell copper	$ 3.1
Time period for open copper future contract sales	5 months

Derivative Instruments and He_4

Derivative Instruments and Hedging Activities - Derivative Assets and Liabilities (Details) - Designated as Hedging Instrument [Member] - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Derivatives, Fair Value [Line Items]
Assets fair value	$ 87	$ 1,009
Liabilities fair value	(1,279)	(3,155)
Other Current Asset [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Other current assets: Gain positions	88	1,014
Other current assets: Loss positions	(1)	(5)
Other Current Liabilities [Member] | Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Other current liability: Gain positions	103	55
Other current liability: Loss positions	$ (1,382)	$ (3,210)

Derivative Instruments and He_5

Derivative Instruments and Hedging Activities - Effects on Statement of Income and Amounts Recognized In and Reclassified From AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss Recognized in AOCI (Effective Portion), Net of Tax	$ (802)	$ (389)
Gain Reclassified from AOCI (Effective Portion), Net of Tax	(371)	1,536
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on commodity contracts (nonqualifying)	4,227	(6,078)
Commodity Contract [Member] | Fair Value Hedging [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on the derivatives in designated and qualifying fair value hedges	391	(724)
Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss Recognized in AOCI (Effective Portion), Net of Tax	(793)	(574)
Commodity Contract [Member] | Cash Flow Hedging [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Reclassified from AOCI (Effective Portion), Net of Tax	(371)	990
Inventories [Member] | Fair Value Hedging [Member] | Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (loss) on the derivatives in designated and qualifying fair value hedges	(385)	625
Interest Rate Swap [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss Recognized in AOCI (Effective Portion), Net of Tax		0
Interest Rate Swap [Member] | Cash Flow Hedging [Member] | Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Reclassified from AOCI (Effective Portion), Net of Tax		546
Other [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss Recognized in AOCI (Effective Portion), Net of Tax	(9)	185
Other [Member] | Cash Flow Hedging [Member] | Other [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain Reclassified from AOCI (Effective Portion), Net of Tax	$ 0	$ 0

Property, Plant, and Equipmen_3

Property, Plant, and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016	[1]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 891,099	$ 822,208
Less accumulated depreciation	(520,466)	(517,887)
Property, plant, and equipment, net	370,633	304,321
Depreciation	35,118	30,800	[1]	$ 30,827
Land and Land Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	32,132	18,740
Building [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	201,176	144,527
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	635,173	649,667
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 22,618	$ 9,274
[1]	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.

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets - Schedule of Changes in Carrying Amount of Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Goodwill		$ 173,398,000
Accumulated impairment charges, beginning of year		(49,405,000)
Goodwill, net, beginning balance	$ 130,293,000	123,993,000
Additions	22,819,000	3,852,000
Currency translation	(2,777,000)	2,448,000
Goodwill	199,740,000		$ 173,398,000
Accumulated impairment loss, end of year	(49,405,000)		(49,405,000)
Goodwill, net, ending balance	150,335,000	130,293,000	123,993,000
Impairment charges	0	0	0
Jungwoo-Mueller [Member]
Goodwill [Roll Forward]
Purchase price allocation adjustments	(200,000)
Heatlink Group [Member]
Goodwill [Roll Forward]
Purchase price allocation adjustments	2,800,000
Piping Systems [Member]
Goodwill [Roll Forward]
Goodwill		160,128,000
Accumulated impairment charges, beginning of year		(40,552,000)
Goodwill, net, beginning balance	125,876,000	119,576,000
Additions	5,049,000	3,852,000
Currency translation	(2,777,000)	2,448,000
Goodwill	168,700,000		160,128,000
Accumulated impairment loss, end of year	(40,552,000)		(40,552,000)
Goodwill, net, ending balance	128,148,000	125,876,000	119,576,000
Industrial Metals [Member]
Goodwill [Roll Forward]
Goodwill		8,854,000
Accumulated impairment charges, beginning of year		(8,853,000)
Goodwill, net, beginning balance	1,000	1,000
Additions	0	0
Currency translation	0	0
Goodwill	8,854,000		8,854,000
Accumulated impairment loss, end of year	(8,853,000)		(8,853,000)
Goodwill, net, ending balance	1,000	1,000	1,000
Climate [Member]
Goodwill [Roll Forward]
Goodwill		4,416,000
Accumulated impairment charges, beginning of year		0
Goodwill, net, beginning balance	4,416,000	4,416,000
Additions	17,770,000	0
Currency translation	0	0
Goodwill	22,186,000		4,416,000
Accumulated impairment loss, end of year	0		0
Goodwill, net, ending balance	$ 22,186,000	$ 4,416,000	$ 4,416,000

Goodwill and Other Intangible_4

Goodwill and Other Intangible Assets - Schedule of Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Carrying amount of intangible assets [Abstract]
Net Carrying Amount	$ 61,971
Amortization	4,400	$ 3,100	$ 4,300
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2,019	5,242
2,020	5,047
2,021	4,773
2,022	4,693
2,023	4,297
Thereafter	37,919
Expected amortization expense	61,971
Customer relationships [Member]
Carrying amount of intangible assets [Abstract]
Gross Carrying Amount	43,104	36,518
Accumulated Amortization	(6,309)	(4,644)
Net Carrying Amount	36,795	31,874
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Expected amortization expense	36,795	31,874
Non-compete agreements [Member]
Carrying amount of intangible assets [Abstract]
Gross Carrying Amount	2,400	2,834
Accumulated Amortization	(1,582)	(1,497)
Net Carrying Amount	818	1,337
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Expected amortization expense	818	1,337
Patents and technology [Member]
Carrying amount of intangible assets [Abstract]
Gross Carrying Amount	17,879	7,673
Accumulated Amortization	(2,595)	(1,868)
Net Carrying Amount	15,284	5,805
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Expected amortization expense	15,284	5,805
Trade names and licenses [Member]
Carrying amount of intangible assets [Abstract]
Gross Carrying Amount	9,173	4,977
Accumulated Amortization	(2,188)	(1,575)
Net Carrying Amount	6,985	3,402
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Expected amortization expense	6,985	3,402
Other [Member]
Carrying amount of intangible assets [Abstract]
Gross Carrying Amount	2,526	213
Accumulated Amortization	(437)	(623)
Net Carrying Amount	2,089	(410)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Expected amortization expense	2,089	(410)
Other intangible assets [Member]
Carrying amount of intangible assets [Abstract]
Gross Carrying Amount	75,082	52,215
Accumulated Amortization	(13,111)	(10,207)
Net Carrying Amount	61,971	42,008
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
Expected amortization expense	$ 61,971	$ 42,008

Investment in Unconsolidated _3

Investment in Unconsolidated Affiliates - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Schedule of Equity Method Investments [Line Items]
Net loss	$ (20,049)	$ (4,153)
Tecumseh Products Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in joint venture	50.00%
Net loss	$ (14,000)
Gain on settlement	$ 7,000
Second Unconsolidated Affiliate [Member]
Schedule of Equity Method Investments [Line Items]
Interest in joint venture	50.00%
Cayan Ventures and Bahrain Mumtalakat Holding Company [Member]
Schedule of Equity Method Investments [Line Items]
Interest in joint venture	40.00%
Cash invested in joint venture	$ 4,500
Mueller Middle East BSC [Member]
Schedule of Equity Method Investments [Line Items]
Interest in joint venture	40.00%
Net loss	$ (2,600)
Labor Claim [Member] | Tecumseh Products Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Loss related to certain labor claim contingencies	$ 3,000

Investment in Unconsolidated _4

Investment in Unconsolidated Affiliates - Summary of Financial Information of Equity Method Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Balance sheet data [Abstract]
Current assets	$ 228,214	$ 246,127
Noncurrent assets	114,257	139,200
Current liabilities	175,371	174,710
Noncurrent liabilities	57,216	58,334
Income statement data [Abstract]
Net sales	509,517	556,600
Gross profit	59,385	75,600
Net loss	$ (20,049)	$ (4,153)

Debt - Schedule of Debt (Detail

Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Debt Instrument [Line Items]
Long-term debt, gross	$ 497,555	$ 466,247
Less debt issuance costs	(857)	(1,175)
Less current portion of debt	(7,101)	(16,480)
Long-term debt	489,597	448,592
Subordinated Debt [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 284,479	284,536
Debt, stated interest rate	6.00%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 195,000	160,000
Debt, stated interest rate	3.97%
Jungwoo Mueller Line of Credit Due 2019 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 5,264	5,119
Debt, stated interest rate	2.86%
Jungwoo Mueller Line of Credit Due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 5,104	8,648
Debt, stated interest rate	3.45%
2001 Series IRB's With Interest at 1.23% Due 2021 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 2,250	3,250
Debt, stated interest rate	3.22%
Other [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 5,458	$ 4,694

Debt - Narrative (Details)

Debt - Narrative (Details)	Mar. 09, 2017$ / shares	Dec. 29, 2018USD ($)	Dec. 30, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 29, 2018KRW (₩)
Debt Instrument [Line Items]
Cash dividend (in dollars per share) | $ / shares	$ 3
Cash dividend, subordinated debentures (in dollars per share) | $ / shares	$ 5
Interest paid		$ 25,200,000	$ 13,800,000	$ 7,100,000
Subordinated Debt [Member]
Debt Instrument [Line Items]
Debt, stated interest rate		6.00%			6.00%
Debt instrument, call feature, period, latest		5 years
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity		$ 350,000,000
Credit Agreement [Member]
Debt Instrument [Line Items]
Outstanding letters of credit		8,500,000
Jungwoo-Mueller [Member]
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity		$ 25,300,000			₩ 28,800,000,000
Minimum [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Credit facility commitment fee		0.15%
Maximum [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Credit facility commitment fee		0.30%
LIBOR [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		1.625%
LIBOR [Member] | Minimum [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		1.125%
LIBOR [Member] | Maximum [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		1.625%
Base Rate [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		0.625%
Base Rate [Member] | Minimum [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		0.125%
Base Rate [Member] | Maximum [Member] | Credit Agreement [Member]
Debt Instrument [Line Items]
Basis spread on variable rate		0.625%

Debt - Redemption Schedule (Det

Debt - Redemption Schedule (Details) - Subordinated Debt [Member]	12 Months Ended
	Dec. 29, 2018
2018 [Member]
Debt Instrument [Line Items]
Redemption Price	105.00%
2019 [Member]
Debt Instrument [Line Items]
Redemption Price	104.00%
2020 [Member]
Debt Instrument [Line Items]
Redemption Price	103.00%
2021 [Member]
Debt Instrument [Line Items]
Redemption Price	102.00%
2022 and thereafter [Member]
Debt Instrument [Line Items]
Redemption Price	100.00%

Debt - Aggregate Annual Maturit

Debt - Aggregate Annual Maturities (Details) $ in Thousands	Dec. 29, 2018USD ($)
Long-term Debt, Fiscal Year Maturity [Abstract]
2,019	$ 7,101
2,020	6,831
2,021	195,955
2,022	618
2,023	402
Thereafter	286,648
Long-term debt	$ 497,555

Debt - Net Interest Expense (De

Debt - Net Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016
Debt Disclosure [Abstract]
Interest expense	$ 25,349	$ 19,716		$ 7,749
Capitalized interest	(150)	(214)		(362)
Net interest expense	$ 25,199	$ 19,502	[1]	$ 7,387	[1]
[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.

Benefit Plans - Benefit Plan In

Benefit Plans - Benefit Plan Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Change in fair value of plan assets:
Beginning balance	$ 186,336
Ending balance	164,603	$ 186,336
Actuarial net loss	1,800
Prior service credit	$ (900)
Payable maximum period to be considered current	12 months
Funded status of the plans recognized [Abstract]
Long-term liability	$ (14,237)	(11,606)
Components of net periodic benefit cost [Abstract]
Net periodic benefit (income) cost	$ (2,914)	(1,150)	$ 1,687
Weighted average assumptions in net periodic benefit calculations [Abstract]
Ultimate health care cost trend rate	3.00%
Minimum [Member]
Weighted average assumptions in net periodic benefit calculations [Abstract]
Annual assumed rate of increase in the per capita cost of covered benefits	6.40%
Maximum [Member]
Weighted average assumptions in net periodic benefit calculations [Abstract]
Annual assumed rate of increase in the per capita cost of covered benefits	8.40%
Pension Plan [Member]
Change in benefit obligation [Roll Forward]
Obligation at beginning of year	$ 186,766	178,736
Service cost	88	128	532
Interest cost	5,745	6,344	7,553
Actuarial (gain) loss	(10,637)	4,688
Benefit payments	(10,368)	(10,171)
Settlement charge	0	0
Foreign currency translation adjustment	(4,855)	7,041
Obligation at end of year	166,739	186,766	178,736
Change in fair value of plan assets:
Beginning balance	186,336	169,140
Actual return on plan assets	(8,282)	19,175
Employer contributions	999	2,271
Benefit payments	(10,368)	(10,171)
Foreign currency translation adjustment	(4,082)	5,921
Ending balance	164,603	186,336	169,140
Underfunded status at end of year	(2,136)	(430)
Unrecognized net actuarial loss	39,101	34,627
Unrecognized prior service credit	0	0
Funded status of the plans recognized [Abstract]
Long-term asset	10,580	9,894
Current liability	0	0
Long-term liability	(12,716)	(10,324)
Total underfunded status	(2,136)	(430)
Components of net periodic benefit cost [Abstract]
Service cost	88	128	532
Interest cost	5,745	6,344	7,553
Expected return on plan assets	(9,522)	(9,374)	(9,615)
Amortization of net loss (gain)	1,151	2,206	2,898
Settlement charge	0	0	1,214
Net periodic benefit (income) cost	$ (2,538)	$ (696)	$ 2,582
Weighted average assumptions in benefit obligations calculations [Abstract]
Discount rate	3.72%	3.22%
Expected long-term return on plan assets	5.05%	5.27%
Rate of inflation	3.40%	3.30%
Weighted average assumptions in net periodic benefit calculations [Abstract]
Discount rate	3.22%	3.61%	4.02%
Expected long-term return on plan assets	5.27%	5.56%	5.59%
Rate of inflation	3.30%	3.30%	3.20%
Other Postretirement Benefits Plan [Member]
Change in benefit obligation [Roll Forward]
Obligation at beginning of year	$ 16,407	$ 15,274
Service cost	235	235	$ 232
Interest cost	447	599	594
Actuarial (gain) loss	(1,185)	923
Benefit payments	(892)	(883)
Settlement charge	(171)	(209)
Foreign currency translation adjustment	(459)	468
Obligation at end of year	14,382	16,407	15,274
Change in fair value of plan assets:
Beginning balance	0	0
Actual return on plan assets	0	0
Employer contributions	892	883
Benefit payments	(892)	(883)
Foreign currency translation adjustment	0	0
Ending balance	0	0	0
Underfunded status at end of year	(14,382)	(16,407)
Unrecognized net actuarial loss	170	1,540
Unrecognized prior service credit	(6,387)	(7,289)
Funded status of the plans recognized [Abstract]
Long-term asset	0	0
Current liability	(1,080)	(1,070)
Long-term liability	(13,302)	(15,337)
Total underfunded status	(14,382)	(16,407)
Components of net periodic benefit cost [Abstract]
Service cost	235	235	232
Interest cost	447	599	594
Amortization of net loss (gain)	92	(42)	(60)
Amortization of prior service credit	(902)	(901)	(896)
Settlement charge	38	17	0
Net periodic benefit (income) cost	$ (90)	$ (92)	$ (130)
Weighted average assumptions in benefit obligations calculations [Abstract]
Discount rate	4.56%	3.89%
Rate of compensation increases	5.00%	5.00%
Weighted average assumptions in net periodic benefit calculations [Abstract]
Discount rate	3.89%	4.21%	4.25%
Rate of compensation increases	5.00%	5.00%	5.00%
United Kingdom [Member] | Pension Plan [Member]
Change in fair value of plan assets:
Percent of above benefit obligation on company sponsored UK pension plan	45.00%	44.00%
Percent above plan assets on company sponsored UK pension plan	37.00%	39.00%

Benefit Plans - Pension Assets

Benefit Plans - Pension Assets by Percentage (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	$ 164,603	$ 186,336
Cash and Cash Equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	12,984	5,364
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	$ 164,603	$ 186,336	$ 169,140
Asset category [Abstract]
Total plan assets	100.00%	100.00%
Expected long-term rate of return on plan assets	5.05%	5.27%
Pension Plan [Member] | Equity Securities [Member]
Asset category [Abstract]
Total plan assets	35.00%	46.00%
Pension Plan [Member] | Fixed Income Funds [Member]
Asset category [Abstract]
Total plan assets	54.00%	48.00%
Pension Plan [Member] | Cash and Cash Equivalents [Member]
Asset category [Abstract]
Total plan assets	8.00%	3.00%
Pension Plan [Member] | Alternative Investments [Member]
Asset category [Abstract]
Total plan assets	3.00%	3.00%
Pension Plan [Member] | Minimum [Member] | Fixed Income Funds [Member]
Asset category [Abstract]
Total plan assets	60.00%
Pension Plan [Member] | Maximum [Member] | Equity Securities [Member]
Asset category [Abstract]
Total plan assets	30.00%
Pension Plan [Member] | Maximum [Member] | Alternative Investments [Member]
Asset category [Abstract]
Total plan assets	5.00%

Benefit Plans - Pension Asset_2

Benefit Plans - Pension Assets by Fair Value Level (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	$ 164,603	$ 186,336
Approximate percentage of mutual funds actively managed	61.00%	66.00%
Approximate percentage of mutual funds indexed funds	39.00%	34.00%
Percentage of mutual funds' assets invested in U.S equities	5.00%	5.00%
Percent of mutual funds assets invested in non US equities	35.00%	41.00%
Percent of mutual funds assets invested in US fixed income securities	59.00%	52.00%
Percent of mutual funds assets invested in non US fixed income securities	1.00%	2.00%
Approximate percentage of common stock invested in major industry		91.00%
Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	$ 12,984	$ 24,889
Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	146,591	156,442
Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	5,028	5,005
Cash and Cash Equivalents [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	12,984	5,364
Cash and Cash Equivalents [Member] | Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	12,984	5,364
Cash and Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	0	0
Cash and Cash Equivalents [Member] | Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	0	0
Defined Benefit Plan, Equity Securities, Common Stock [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset		11,113
Defined Benefit Plan, Equity Securities, Common Stock [Member] | Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset		11,113
Defined Benefit Plan, Equity Securities, Common Stock [Member] | Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset		0
Defined Benefit Plan, Equity Securities, Common Stock [Member] | Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset		0
Mutual Funds [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	146,591	164,854
Mutual Funds [Member] | Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	0	8,412
Mutual Funds [Member] | Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	146,591	156,442
Mutual Funds [Member] | Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	0	0
Limited Partnerships [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	5,028	5,005
Limited Partnerships [Member] | Level 1 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	0	0
Limited Partnerships [Member] | Level 2 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	0	0
Limited Partnerships [Member] | Level 3 [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Long-term asset	$ 5,028	$ 5,005

Benefit Plans - Assets of the P

Benefit Plans - Assets of the Plan Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) $ in Thousands	12 Months Ended
	Dec. 29, 2018USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 186,336
Ending balance	164,603
Pension Plan [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	186,336
Ending balance	164,603
Pension Plan [Member] | Limited Partner [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Redemptions	(108)
Subscriptions	108
Net appreciation in fair value	23
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	5,005
Ending balance	5,028
Fair Value, Inputs, Level 3 [Member] | Pension Plan [Member] | Limited Partner [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	5,005
Ending balance	$ 5,028

Benefit Plans - Contributions a

Benefit Plans - Contributions and Benefit Payments (Details) $ in Thousands	Dec. 29, 2018USD ($)
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company's expected contribution to benefit plans in next fiscal year	$ 100
2,019	10,416
2,020	10,342
2,021	10,283
2,022	10,241
2,023	10,196
2024-2028	49,820
Total	101,298
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company's expected contribution to benefit plans in next fiscal year	1,100
2,019	1,102
2,020	1,244
2,021	1,061
2,022	1,112
2,023	1,226
2024-2028	5,821
Total	$ 11,566

Benefit Plans - Contributions_2

Benefit Plans - Contributions and Benefit Payments, Multiemployer Plan, 401(k) Plans and UMWA Benefit Plans (Details) $ in Thousands	12 Months Ended
	Dec. 29, 2018USD ($)bargain_agreement	Dec. 30, 2017USD ($)	Dec. 31, 2016USD ($)
IAM Plan Trusts [Abstract]
Number of collective bargaining agreements | bargain_agreement	2
Pension contributions under the I.A.M. pension plan trusts	$ 1,300	$ 1,100	$ 1,100
Maximum percentage of employer contributions (less than)	5.00%
401 (k) Plan [Abstract]
Compensation expense for the Company's matching contribution	$ 5,100	5,100	5,200
Contributions to UMWA 1992 Benefit Plan	$ 153	$ 182	$ 197

Commitments and Contingencies -

Commitments and Contingencies - Environmental (Details) $ in Millions	1 Months Ended		12 Months Ended			36 Months Ended
	Jan. 31, 2018USD ($)unilateral_administrative_orders	Sep. 30, 2014USD ($)property	Dec. 29, 2018USD ($)	Dec. 30, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 29, 2018USD ($)	Dec. 29, 2018potentially_responsible_party	Dec. 29, 2018smelter_site
Site Contingency [Line Items]
Environmental expense			$ 2	$ 7.5	$ 0.9
Environmental reserves			23.6	$ 28		$ 23.6
Expected environmental expenditures for 2019			3.6			3.6
Expected environmental expenditures for 2020			0.6			0.6
Expected environmental expenditures for 2021			0.6			0.6
Expected environmental expenditures for 2022			0.6			0.6
Expected environmental expenditures for 2023			0.7			0.7
Expected environmental expenditures after 2023			17.5			17.5
Lead Refinery Site [Member]
Lead Refinery Site [Abstract]
Site contingency, financial guarantee			1			1
Lead Refinery NPL Site [Member]
Site Contingency [Line Items]
Environmental reserves	$ 4.5		2.5			2.5
Lead Refinery Site [Abstract]
Number of UAOs issued | unilateral_administrative_orders	2
Site contingency, total costs	$ 25
Site contingency, amount agreed upon to pay PRPs for past costs	$ 2
Payments for unilateral administrative orders			4.5
Non-Operating Properties [Member] | Southeast Kansas Sites [Member]
Site Contingency [Line Items]
Environmental reserves			$ 5.6			5.6
Number of parties involved in settlement negotiations							2	3
Non-Operating Properties [Member] | Shasta Area Mine Sites [Member]
Site Contingency [Line Items]
Period of permit, implementation of Best Management Practices			10 years
Environmental spending						1.4
Estimated number of years until mitigation resolution			30 years
Non-Operating Properties [Member] | Shasta Area Mine Sites [Member] | Minimum [Member]
Site Contingency [Line Items]
Mitigation estimates			$ 12.8
Non-Operating Properties [Member] | Shasta Area Mine Sites [Member] | Maximum [Member]
Site Contingency [Line Items]
Mitigation estimates			$ 17.5
Non-Operating Properties [Member] | Lead Refinery Site [Member]
Site Contingency [Line Items]
Environmental expense						$ 0.7
Estimated number of years until mitigation resolution			18 years
Lead Refinery Site [Abstract]
EPA's estimated cost of site remediation		$ 26
Number of surrounding properties | property		300
Non-Operating Properties [Member] | Lead Refinery Site [Member] | Minimum [Member]
Site Contingency [Line Items]
Mitigation estimates			$ 1.7
Non-Operating Properties [Member] | Lead Refinery Site [Member] | Maximum [Member]
Site Contingency [Line Items]
Mitigation estimates			2.1
Operating Properties [Member] | Mueller Copper Tube Products, Inc. [Member]
Site Contingency [Line Items]
Estimated number of years until mitigation resolution						7 years
Operating Properties [Member] | Mueller Copper Tube Products, Inc. [Member] | Minimum [Member]
Site Contingency [Line Items]
Mitigation estimates			0.7
Operating Properties [Member] | Mueller Copper Tube Products, Inc. [Member] | Maximum [Member]
Site Contingency [Line Items]
Mitigation estimates			$ 1.1

Commitments and Contingencies_2

Commitments and Contingencies - United States Department of Commerce Antidumping Review (Details)	Jul. 13, 2018USD ($)	Nov. 30, 2018USD ($)	Nov. 27, 2015USD ($)	Dec. 29, 2018	Oct. 31, 2008Import_entry	Apr. 19, 2010
United States Department of Commerce Antidumping Review [Member]
Loss Contingencies [Line Items]
Assignment of antidumping duty rate on U.S. imports by Company subsidiaries						48.33%
Payment request for interest and duties			$ 3,000,000
Number of import entries | Import_entry					795
Equal Employment Opportunity Commission Matter [Member]
Loss Contingencies [Line Items]
Term of consent decree				2 years 6 months
Monetary relief awarded to individual claims	$ 1,000,000
Deepwater Horizon Economic and Property Damage Claim [Member]
Loss Contingencies [Line Items]
Gain award for settlement		$ 27,400,000
Gain contingency, payment of legal and advisory fees, percent of total		20.00%

Commitments and Contingencies_3

Commitments and Contingencies - Leases (Details) - Facilities Vehicles and Equipment [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Operating Leased Assets [Line Items]
Lease payments scheduled for 2019	$ 6.6
Lease payments scheduled for 2020	5.6
Lease payments scheduled for 2021	4.4
Lease payments scheduled for 2022	3.7
Lease payments scheduled for 2023	2.6
Lease payments scheduled after 2023	15.4
Lease expense	$ 11.5	$ 11.9	$ 11.6

Income Taxes - Components of In

Income Taxes - Components of Income Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic	$ 105,455	$ 76,876	$ 103,576
Foreign	44,962	50,096	42,454
Income before income taxes	$ 150,417	$ 126,972	$ 146,030

Income Taxes - Components of _2

Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016
Current tax expense:
Federal	$ 17,974	$ 28,584		$ 32,262
Foreign	9,650	10,219		5,667
State and local	3,158	2,241		3,210
Current tax expense	30,782	41,044		41,139
Deferred tax expense (benefit):
Federal	(1,381)	(1,764)		2,004
Foreign	551	1,118		5,099
State and local	1,000	(2,514)		(105)
Deferred tax expense (benefit)	170	(3,160)	[1]	6,998	[1]
Income tax expense	$ 30,952	$ 37,884	[2]	$ 48,137	[2]
[1]	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.
[2]	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.

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017		Dec. 31, 2016
Income Tax Disclosure [Abstract]
Expected income tax expense	$ 31,588	$ 44,440		$ 51,110
State and local income tax, net of federal benefit	3,495	1,135		1,982
Effect of foreign statutory rates different from U.S. and other foreign adjustments	759	(6,026)		(4,092)
Changes in valuation allowances	1,133	0		0
U.S. production activities deduction	0	(1,575)		(3,063)
Investment in unconsolidated affiliates	(3,909)	216		1,030
Benefit of stock-based compensation deductions	(41)	(2,160)		(656)
Effect of tax on accumulated foreign earnings	(4,415)	12,893		0
Effect of tax rate change on net deferred tax liability balance	0	(12,067)		0
Other, net	2,342	1,028		1,826
Income tax expense	$ 30,952	$ 37,884	[1]	$ 48,137	[1]
[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.

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Increase in tax expense due to one-time transition tax liability	$ (4,400)	$ 12,900
Increase in income tax expense recorded for its one-time transition tax liability, effect on diluted earnings per share (in dollars per share)	$ (0.08)	$ 0.22
Unrecognized tax on undistributed foreign earnings	$ 4,000
Income tax benefit as a result of the remeasurement of deferred tax balance		$ (12,100)
Income tax benefit as a result of the remeasurement of deferred tax balance, effect on diluted earnings per share (in dollars per share)		$ (0.21)
Income tax penalties	0	$ 0	$ 0
State income tax credit carryforwards with expiration	4,300
Other state income tax credit carryforwards with unlimited life	11,700
State net operating loss carryforwards with potential tax benefits	11,600
Valuation allowances	16,000
Federal and foreign tax attributes with potential tax benefits	5,800
Income taxes paid	$ 38,100	$ 42,500	$ 40,100

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 29, 2018	Dec. 30, 2017
Deferred tax assets [Abstract]
Inventories	$ 12,297	$ 10,598
Other postretirement benefits and accrued items	9,213	9,239
Other reserves	7,847	9,029
Federal and foreign tax attributes	6,252	11,936
State tax attributes, net of federal benefit	27,651	29,720
Stock-based compensation	2,949	2,102
Basis difference in unconsolidated affiliates	1,067	0
Total deferred tax assets	67,276	72,624
Less valuation allowance	(25,311)	(30,316)
Deferred tax assets, net of valuation allowance	41,965	42,308
Deferred tax liabilities:
Property, plant, and equipment	44,910	43,972
Pension	250	3,841
Basis difference in unconsolidated affiliates	0	203
Total deferred tax liabilities	45,160	48,016
Net deferred tax liabilities	$ (3,195)	$ (5,708)

Equity (Details)

Equity (Details)	Dec. 29, 2018shares
Equity [Abstract]
Authorization to repurchase shares of common stock (in shares)	20,000,000
Shares repurchased (in shares)	6,100,000

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 8	$ 7.5	$ 6.4
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value of options granted (in dollars per share)	$ 9.64	$ 9.38	$ 7.87
Total intrinsic value of options exercised	$ 0.9	$ 10.2	$ 2.5
Fair value of options vested	1	1	0.3
Aggregate intrinsic value of all outstanding options	$ 2.7
Weighted average remaining contractual term of all outstanding options	6 years
Outstanding options, exercisable (in shares)	562
Aggregate intrinsic value of current exercisable shares	$ 2.7
Weighted average exercise price (in dollars per share)	$ 19.87
Weighted average remaining contractual term	4 years 6 months 18 days
Compensation for stock awards not yet recognized	$ 2.2
Compensation recognition period	3 years 9 months 18 days
Shares available for future issuance (in shares)	344
Employee Stock Option [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options vesting period	5 years
Stock options expiration period	10 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of options vested	$ 3.7	$ 3.5	$ 4.7
Compensation for stock awards not yet recognized	$ 17.5
Compensation recognition period	3 years 2 months 24 days
Granted (in dollars per share)	$ 32.04	$ 30.97	$ 34.04
Aggregate intrinsic value	$ 21.8

Stock-Based Compensation - Assu

Stock-Based Compensation - Assumptions in Determining Fair Value of Options Granted (Details) - Employee Stock Option [Member]	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	7 years 7 months 12 days	7 years 8 months 12 days	6 years 8 months 12 days
Expected price volatility	27.20%	28.90%	25.60%
Risk-free interest rate	2.90%	2.10%	1.60%
Dividend yield	1.30%	1.30%	1.00%

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Options and Restricted Stock Awards (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Employee Stock Option [Member]
Options outstanding [Roll Forward]
Beginning balance (in shares)	947
Granted (in shares)	142
Exercised (in shares)	(57)
Forfeited (in shares)	(18)
Ending balance (in shares)	1,014	947
Weighted average exercise price [Roll Forward]
Beginning balance (in dollars per share)	$ 22.31
Granted (in dollars per share)	31.33
Exercised (in dollars per share)	15.10
Forfeited (in dollars per share)	26.78
Ending balance (in dollars per share)	$ 23.90	$ 22.31
Restricted Stock [Member]
Restricted stock [Roll Forward]
Beginning balance (in shares)	781
Granted (in shares)	276
Exercised (in shares)	(124)
Forfeited (in shares)	(3)
Ending balance (in shares)	930	781
Weighted average grant date fair value [Abstract]
Beginning balance (in dollars per share)	$ 31.83
Granted (in dollars per share)	32.04	$ 30.97	$ 34.04
Exercised (in dollars per share)	29.95
Forfeited (in dollars per share)	32.60
Ending balance (in dollars per share)	$ 32.14	$ 31.83

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Income (Loss) - Changes in AOCI by Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of year	$ 536,028
Total other comprehensive (loss) income, net	(30,074)	$ 17,272	$ (14,541)
Balance at end of year	563,260	536,028
Cumulative Translation Adjustment [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of year	(38,163)	(49,965)
Other comprehensive income (loss) before reclassifications	(16,094)	15,579
Amounts reclassified from AOCI	0	(3,777)
Total other comprehensive (loss) income, net	(16,094)
Reclassification of stranded effects of the Act	0
Balance at end of year	(54,257)	(38,163)	(49,965)
Unrealized Losses on Derivatives [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of year	847	(300)
Other comprehensive income (loss) before reclassifications	(802)	(389)
Amounts reclassified from AOCI	(371)	1,536
Total other comprehensive (loss) income, net	(1,173)
Reclassification of stranded effects of the Act	112
Balance at end of year	(214)	847	(300)
Minimum Pension/OPEB Liability Adjustment [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of year	(20,610)	(23,046)
Other comprehensive income (loss) before reclassifications	(3,642)	1,394
Amounts reclassified from AOCI	303	1,042
Total other comprehensive (loss) income, net	(3,339)
Reclassification of stranded effects of the Act	(1,018)
Balance at end of year	(24,967)	(20,610)	(23,046)
Unrealized Gains on Equity Investments [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of year	0	380
Other comprehensive income (loss) before reclassifications	0	(1)
Amounts reclassified from AOCI	0	(379)
Total other comprehensive (loss) income, net	0
Reclassification of stranded effects of the Act	0
Balance at end of year	0	0	380
Accumulated Other Comprehensive Income Attributable to Unconsolidated Affiliates [Member]
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of year	6,870	5,975
Other comprehensive income (loss) before reclassifications	(8,686)	895
Amounts reclassified from AOCI	0	0
Total other comprehensive (loss) income, net	(8,686)
Reclassification of stranded effects of the Act	1,462
Balance at end of year	(354)	6,870	5,975
Accumulated other comprehensive loss:
Changes in accumulated other comprehensive income [Roll Forward]
Balance at beginning of year	(51,056)	(66,956)	(54,990)
Other comprehensive income (loss) before reclassifications	(29,224)	17,478
Amounts reclassified from AOCI	(68)	(1,578)
Total other comprehensive (loss) income, net	(29,292)	15,900	(11,966)
Reclassification of stranded effects of the Act	556
Balance at end of year	$ (79,792)	$ (51,056)	$ (66,956)

Accumulated Other Comprehensi_4

Accumulated Other Comprehensive Income (Loss) - Reclassification Adjustments out of AOCI (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
Reclassification Adjustments out of AOCI [Abstract]
Cost of goods sold									$ 2,150,400	$ 1,940,617	[1]	$ 1,723,499	[1]
Interest expense									25,199	19,502	[1]	7,387	[1]
Income tax (benefit) expense									30,952	37,884	[1]	48,137	[1]
Other income, net									(3,967)	(2,951)	[1]	(295)	[1]
Net of tax and noncontrolling interests	$ (26,857)	$ (20,292)	$ (33,182)	$ (24,128)	$ (5,720)	$ (22,258)	$ (27,633)	$ (29,987)	(104,459)	(85,598)	[1]	(99,727)	[1]
Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustments out of AOCI [Abstract]
Cost of goods sold									(429)	1,309		1,061
Interest expense									0	851		361
Income tax (benefit) expense									58	(624)		(113)
Net of tax and noncontrolling interests									(371)	1,536		1,309
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustments out of AOCI [Abstract]
Income tax (benefit) expense									(38)	(221)		(521)
Other income, net									341	1,263		1,942
Net of tax and noncontrolling interests									303	1,042		1,421
Accumulated Net Gain (Loss) From Divestiture Attributable to Parent [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustments out of AOCI [Abstract]
Income tax (benefit) expense									0	0		0
Gain on sale of assets									0	(3,777)		0
Net of tax and noncontrolling interests									0	(3,777)		0
Unrealized Gains on Equity Investments [Member] | Amount Reclassified from AOCI [Member]
Reclassification Adjustments out of AOCI [Abstract]
Income tax (benefit) expense									0	232		0
Other income, net									0	(611)		0
Net of tax and noncontrolling interests									$ 0	$ (379)		$ 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.

Quarterly Financial Informati_3

Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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	[1]
Quarterly Financial Information Disclosure [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
Gross profit	85,133	79,002	98,953	94,390	66,907	79,101	89,955	89,493
Consolidated net income	27,731	20,863	33,882	24,344	5,969	22,754	27,833	30,455	106,820	87,011	[1],[2]	99,754	[2]
Net income attributable to Mueller Industries, Inc.	$ 26,857	$ 20,292	$ 33,182	$ 24,128	$ 5,720	$ 22,258	$ 27,633	$ 29,987	$ 104,459	$ 85,598	[1]	$ 99,727
Basic earnings per share (in dollars per share)	$ 0.47	$ 0.36	$ 0.58	$ 0.42	$ 0.10	$ 0.39	$ 0.49	$ 0.53	$ 1.84	$ 1.50	[1]	$ 1.76
Diluted earnings per share (in dollars per share)	0.47	0.35	0.58	0.42	0.10	0.39	0.48	0.52	1.82	1.49	[1]	1.74
Dividends per share (in dollars per share)	$ 0.10	$ 0.10	$ 0.10	$ 0.1	$ 0.10	$ 0.10	$ 0.10	$ 8.1	$ 0.4	$ 8.4	[1]	$ 0.375
Impairment charges					$ 1,100				$ 0	$ 1,466	[1],[2]	$ 6,778	[2]
Interest expense					4,300
Environmental expense, non operating properties					$ 6,200				$ 3,600	$ 4,300
[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.

SCHEDULE II-VALUATION AND QUA_2

SCHEDULE II-VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 980	$ 637	$ 623
Charged to costs and expenses	(286)	422	160
Other additions	220	(61)	2
Deductions	78	18	148
Balance at end of year	836	980	637
Balance of valuation allowance	980	637	623
Environmental Reserves [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	28,004	21,864	21,667
Charged to costs and expenses	1,981	7,491	894
Other additions	0	0	0
Deductions	6,366	1,351	697
Balance at end of year	23,619	28,004	21,864
Balance of valuation allowance	28,004	21,864	21,667
SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	30,316	18,681	17,650
Charged to costs and expenses	1,209	7	3
Other additions	150	11,628	1,028
Deductions	6,364	0	0
Balance at end of year	25,311	30,316	18,681
Period increase in valuation allowance		11,600
Balance of valuation allowance	$ 30,316	$ 18,681	$ 17,650