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Income Taxes - MEC - Reconciliation of Effective Income Tax Rate (Details)
12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Schedule of Effective Income Tax Rate Reconciliation [Line Items]      
Federal statutory income tax rate 21.00% 21.00% 21.00%
Income tax credits (124.00%) (27.00%) (16.00%)
State income tax, net of federal income tax benefit (6.00%) (10.00%) 3.00%
Effects of ratemaking (16.00%) (4.00%) (3.00%)
Other, net 2.00% 1.00% (1.00%)
Effective income tax rate (136.00%) (21.00%) 4.00%
Years eligible for renewable energy production tax credit 10 years    
MEC      
Schedule of Effective Income Tax Rate Reconciliation [Line Items]      
Federal statutory income tax rate 21.00% 21.00% 21.00%
Income tax credits (372.00%) (262.00%) (199.00%)
State income tax, net of federal income tax benefit (32.00%) (46.00%) (27.00%)
Effects of ratemaking (23.00%) (20.00%) (17.00%)
Other, net 3.00% (1.00%) (1.00%)
Effective income tax rate (403.00%) (308.00%) (223.00%)
Years eligible for renewable energy production tax credit 10 years