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Derivatives - Narrative (Details) € in Millions, $ in Millions, kr in Billions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2022 USD ($) MWh t | Dec. 31, 2022 EUR (€) | Dec. 31, 2022 ISK (kr) | Dec. 31, 2021 USD ($)
Supply Commitment [Line Items] |  |  |  |
Restricted cash | $ | $ 0.0 |  |  | $ 8.6
LME Swap |  |  |  |
Supply Commitment [Line Items] |  |  |  |
Open position to offset fixed prices | t | 111,741 |  |  |
Fixed to Floating Swap |  |  |  |
Supply Commitment [Line Items] |  |  |  |
Open position to offset fixed prices | t | 946 |  |  |
FX Swap |  |  |  |
Supply Commitment [Line Items] |  |  |  |
Derivative asset | € |  | € 32.7 |  |
Nordpool Power Price Swap |  |  |  |
Supply Commitment [Line Items] |  |  |  |
Realized gain | $ | $ 16.0 |  |  |
Derivative liability (in MwH) | MWh | 989,880 |  |  |
Indiana Hub Power Price Swaps |  |  |  |
Supply Commitment [Line Items] |  |  |  |
Derivative liability (in MwH) | MWh | 175,200 |  |  |
USD ISK Forward Swap | Not Designated as Hedging Instrument | Short |  |  |  |
Supply Commitment [Line Items] |  |  |  |
Derivative, forward contracts | kr |  |  | kr 5.5 |
USD Euro Forward Swap | Not Designated as Hedging Instrument | Long |  |  |  |
Supply Commitment [Line Items] |  |  |  |
Derivative, forward contracts | € |  | € 8.9 |  |

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- Definition Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI https://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
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- Definition Amount of increase in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI https://asc.fasb.org/extlink&oid=125515794&loc=SL5618551-113959 + Details
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