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Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Other Commitments [Line Items] |  |  |
Land easement non-lease payments expense | $ 1.3 | $ 1.3 | $ 0.6
Westmoreland Arbitration | Pending Litigation |  |  |
Other Commitments [Line Items] |  |  |
Recovery sought | $ 5.5 |  |
OTP | Coyote Station |  |  |
Other Commitments [Line Items] |  |  |
Ownership percentage | 35.00% | 35.00% |
OTP | Federal Energy Regulatory Commission |  |  |
Other Commitments [Line Items] |  |  |
Estimated liability of refund obligation |  | $ 2.5 |
OTP | Construction Programs |  |  |
Other Commitments [Line Items] |  |  |
Long-term purchase commitment, amount | $ 68.0 |  |
Other commitments charged to rent expense | 0.3 | $ 0.1 | $ 0.3
OTP | OTP Land Easements |  |  |
Other Commitments [Line Items] |  |  |
Long-term purchase commitment, amount | $ 34.5 |  |

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- Definition Amount of non-lease land easement payments charged to rent expense in the Electric segment. + References No definition available. + Details
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- Definition The proportionate share of interest (percent) in a jointly owned utility plant. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI http://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
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- Definition The value (monetary amount) of the award the plaintiff seeks in the legal matter. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349 + Details
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