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Commitments and Contingencies - Environmental (Details) $ in Millions | 1 Months Ended | 12 Months Ended | 36 Months Ended |
--- | --- | --- | --- | ---
Jan. 31, 2018 USD ($) unilateral_administrative_orders | Sep. 30, 2014 USD ($) property | Dec. 30, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 26, 2015 USD ($) | Dec. 30, 2017 USD ($) | Dec. 30, 2017 smelter_site | Dec. 30, 2017 Party
Site Contingency [Line Items] |  |  |  |  |  |  |  |
Environmental expense |  |  | $ 7.5 | $ 0.9 | $ 0.1 |  |  |
Environmental reserves |  |  | 28.0 | $ 21.9 |  | $ 28.0 |  |
Expected environmental expenditures for 2018 |  |  | 4.3 |  |  | 4.3 |  |
Expected environmental expenditures for 2019 |  |  | 2.2 |  |  | 2.2 |  |
Expected environmental expenditures for 2020 |  |  | 2.1 |  |  | 2.1 |  |
Expected environmental expenditures for 2021 |  |  | 0.6 |  |  | 0.6 |  |
Expected environmental expenditures for 2022 |  |  | 0.6 |  |  | 0.6 |  |
Expected environmental expenditures after 2022 |  |  | 18.2 |  |  | 18.2 |  |
Lead Refinery Site [Member] |  |  |  |  |  |  |  |
Lead Refinery Site [Abstract] |  |  |  |  |  |  |  |
Site contingency, financial guarantee |  |  | $ 1.0 |  |  | 1.0 |  |
Non-Operating Properties [Member] | Lead Refinery Site [Member] |  |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |  |
Environmental expense |  |  |  |  |  | 0.6 |  |
Estimated number of years until mitigation resolution |  |  | 19 years |  |  |  |  |
Lead Refinery Site [Abstract] |  |  |  |  |  |  |  |
EPA's estimated cost of site remediation |  | $ 26.0 |  |  |  |  |  |
Number of surrounding properties | property |  | 300 |  |  |  |  |  |
Non-Operating Properties [Member] | Lead Refinery Site [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |  |
Mitigation estimates |  |  | $ 1.8 |  |  |  |  |
Non-Operating Properties [Member] | Lead Refinery Site [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |  |
Mitigation estimates |  |  | 3.0 |  |  |  |  |
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 |  |  |  |  |  |  | 3 | 2
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 |  |  |  |  |  | $ 1.2 |  |
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 |  |  | $ 17.6 |  |  |  |  |
Operating Properties [Member] | Mueller Copper Tube Products, Inc. [Member] |  |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |  |
Estimated number of years until mitigation resolution |  |  | 8 years |  |  |  |  |
Operating Properties [Member] | Mueller Copper Tube Products, Inc. [Member] | Minimum [Member] |  |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |  |
Mitigation estimates |  |  | $ 0.8 |  |  |  |  |
Operating Properties [Member] | Mueller Copper Tube Products, Inc. [Member] | Maximum [Member] |  |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |  |
Mitigation estimates |  |  | $ 1.2 |  |  |  |  |
Subsequent Event [Member] | Lead Refinery NPL Site [Member] |  |  |  |  |  |  |  |
Site Contingency [Line Items] |  |  |  |  |  |  |  |
Environmental reserves | $ 4.5 |  |  |  |  |  |  |
Lead Refinery Site [Abstract] |  |  |  |  |  |  |  |
Number of UAOs issued | unilateral_administrative_orders | 2 |  |  |  |  |  |  |
Site contingency, total costs | $ 25.0 |  |  |  |  |  |  |
Site contingency, amount agreed upon to pay PRPs for past costs | $ 2.0 |  |  |  |  |  |  |

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