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Derivatives, Hedging Programs and Other Financial Instruments - Summary of Gain Associated with Derivative Contracts (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2022 | Mar. 31, 2021
Derivative Instruments Gain Loss [Line Items] |  |
Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded | $ 865.9 | $ 262.5
Cost of Products Sold | Not Designated as Hedging Instrument |  |
Derivative Instruments Gain Loss [Line Items] |  |
Gain recognized in our Statements of Consolidated Income | (1.6) | (0.3)
Cost of Products Sold | Not Designated as Hedging Instrument | Alloying Metals |  |
Derivative Instruments Gain Loss [Line Items] |  |
Gain recognized in our Statements of Consolidated Income | (0.6) |
Gain recognized in our Statements of Consolidated Income Unrealized Gain | (1.0) | (0.3)
Cash Flow Hedges |  |
Derivative Instruments Gain Loss [Line Items] |  |
Total of income and expense line items presented in our Statements of Consolidated Income in which the effects of cash flow hedges are recorded | 865.9 | 262.5
Cash Flow Hedges | Cost of Products Sold | Designated as Hedging Instrument |  |
Derivative Instruments Gain Loss [Line Items] |  |
Gain recognized in our Statements of Consolidated Income | (19.9) | (3.8)
Cash Flow Hedges | Cost of Products Sold | Designated as Hedging Instrument | Electricity |  |
Derivative Instruments Gain Loss [Line Items] |  |
Gain recognized in our Statements of Consolidated Income | (0.3) |
Cash Flow Hedges | Cost of Products Sold | Designated as Hedging Instrument | Aluminum |  |
Derivative Instruments Gain Loss [Line Items] |  |
Gain recognized in our Statements of Consolidated Income | (18.7) | (2.9)
Cash Flow Hedges | Cost of Products Sold | Designated as Hedging Instrument | Alloying Metals |  |
Derivative Instruments Gain Loss [Line Items] |  |
Gain recognized in our Statements of Consolidated Income |  | $ (0.9)
Cash Flow Hedges | Cost of Products Sold | Designated as Hedging Instrument | Natural Gas |  |
Derivative Instruments Gain Loss [Line Items] |  |
Gain recognized in our Statements of Consolidated Income | $ (0.9) |

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- Definition The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 924 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 11.L) -URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(a),(d)) -URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227 + Details
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- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 + Details
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