Commitments and Contingencies (Details) $ in Millions	1 Months Ended		9 Months Ended	12 Months Ended
	Jan. 31, 2018 USD ($) unilateral_administrative_order potentially_responsible_party	Nov. 27, 2015 USD ($)	Sep. 25, 2021 USD ($) property potentially_responsible_party	Oct. 31, 2008 Import_entry	Sep. 25, 2021 smelter_site	Sep. 25, 2021 USD ($)	Dec. 26, 2020 USD ($)	Jun. 30, 2018 action	Nov. 08, 2016 USD ($)	Apr. 19, 2010
Loss Contingencies [Line Items]
Term of guarantees			1 year
Payments required to be made under guarantees, maximum						$ 23.9
United States Department of Commerce Antidumping Review
Loss Contingencies [Line Items]
Assignment of antidumping duty rate on U.S. imports by Company subsidiaries (as a percent)										48.33%
Payment for interest and duties		$ 3.0
Number of import entries | Import_entry				795
Deepwater Horizon Economic and Property Damage Claim
Loss Contingencies [Line Items]
Amount awarded to the Company							$ 22.1
Lead Refinery Site
Loss Contingencies [Line Items]
Financial guarantee									$ 1.0
Lead Refinery NPL Site
Loss Contingencies [Line Items]
Environmental reserves	$ 4.5
Number of UAOs | unilateral_administrative_order	2
Number of PRPs | potentially_responsible_party	4
Site contingency, total costs	$ 25.0
Site contingency, amount agreed upon to pay PRPs for past costs	2.0
Site contingency, additional reimbursement of past costs	$ 0.7
Contingency charge			$ 7.6
Number of civil tort actions | action								2
Reserve for settlement						3.3
Non operating Properties | Southeast Kansas Sites
Loss Contingencies [Line Items]
Number of parties involved in settlement negotiations			2		3
Environmental reserves						$ 5.6
Non operating Properties | Shasta Area Mine Sites
Loss Contingencies [Line Items]
Period of permit, implementation of Best Management Practices			10 years
Estimated remediation costs, term			30 years
Non operating Properties | Lead Refinery Site
Loss Contingencies [Line Items]
Number of parties involved in settlement negotiations | potentially_responsible_party			2
Estimated remediation costs, term			16 years
Amount other PRPs will pay to fund cleanup			$ 26.0
Number of surrounding properties | property			300
Non operating Properties | Minimum | Shasta Area Mine Sites
Loss Contingencies [Line Items]
Estimated remediation costs			$ 13.9
Non operating Properties | Minimum | Lead Refinery Site
Loss Contingencies [Line Items]
Estimated remediation costs			1.7
Non operating Properties | Maximum | Shasta Area Mine Sites
Loss Contingencies [Line Items]
Estimated remediation costs			18.0
Non operating Properties | Maximum | Lead Refinery Site
Loss Contingencies [Line Items]
Estimated remediation costs			$ 2.4
Operating Properties | Mueller Copper Tube Products, Inc.
Loss Contingencies [Line Items]
Estimated remediation costs, term			5 years
Operating Properties | Minimum | Mueller Copper Tube Products, Inc.
Loss Contingencies [Line Items]
Estimated remediation costs			$ 0.9
Operating Properties | Maximum | Mueller Copper Tube Products, Inc.
Loss Contingencies [Line Items]
Estimated remediation costs			$ 1.1