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DERIVATIVES - Pre-Tax Effects of Derivatives Not Designated as Hedging (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Derivative instruments not designated as hedging instruments, gain (loss), net | $ (144,000,000) | $ 149,000,000 | $ 233,000,000
Energy-related derivatives | Natural gas revenues |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Derivative instruments not designated as hedging instruments, gain (loss), net | (117,000,000) | 134,000,000 | 223,000,000
Energy-related derivatives | Cost of natural gas |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Derivative instruments not designated as hedging instruments, gain (loss), net | (27,000,000) | 15,000,000 | 10,000,000
Weather derivatives |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Derivative instruments not designated as hedging instruments, gain (loss), net | $ 0 | $ 9,000,000 | $ 3,000,000

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- Definition Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4CC -URI http://asc.fasb.org/extlink&oid=125515794&loc=SL109998890-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=125515794&loc=SL5624171-113959 + Details
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