Commitments and Contingencies - Environmental Laws and Regulations (Details) - PAC - Klamath Hydroelectric System $ in Millions	6 Months Ended
	Jun. 30, 2021 USD ($)
ContractualObligationFiscalYearMaturityScheduleTable [Line Items]
Dam removal cost limit	$ 200
Additional dam removal costs, California bond measure	250
Hydroelectric dam removal cost, additional contingency funding	45
Hydroelectric dam removal cost, total funding	$ 450