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REVENUE FROM CONTRACTS WITH CUSTOMERS - Contract Balances (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] |  |
Accounts Receivable | $ 2,504 | $ 2,614
Contract Assets | 117 | 158
Contract Liabilities | 57 | 61
Contract with customer, liability, revenue recognized | 29 | 33
Unregulated Distributed Generation |  |
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] |  |
Contract Assets | 50 | 81
Contract Liabilities | 39 | 27
Alabama Power |  |
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] |  |
Accounts Receivable | 589 | 632
Contract Assets | 2 | 2
Contract Liabilities | 4 | 6
Georgia Power |  |
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] |  |
Accounts Receivable | 736 | 806
Contract Assets | 63 | 71
Contract Liabilities | 14 | 27
Mississippi Power |  |
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] |  |
Accounts Receivable | 73 | 77
Contract Assets | 0 | 0
Contract Liabilities | 0 | 1
Southern Power |  |
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] |  |
Accounts Receivable | 149 | 112
Contract Assets | 1 | 0
Contract Liabilities | 1 | 1
Southern Company Gas |  |
Revenue, Initial Application Period Cumulative Effect Transition [Line Items] |  |
Accounts Receivable | 753 | 788
Contract Assets | 0 | 0
Contract Liabilities | $ 0 | $ 1

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- Definition Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 8 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130549-203045 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=123360276&loc=SL49130531-203044 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123360276&loc=SL49130533-203044 + Details
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