Income Taxes - PAC - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Components of Income Tax Expense (Benefit) [Line Items]
Years eligible for renewable energy production tax credit	10 years
PAC
Components of Income Tax Expense (Benefit) [Line Items]
Years eligible for renewable energy production tax credit	10 years
Effective income tax reconciliation, amortization of excess deferred income taxes	$ 112	$ 132	$ 93
PAC | State
Components of Income Tax Expense (Benefit) [Line Items]
Effective income tax reconciliation, amortization of excess deferred income taxes	$ 4	$ 118	$ 91