Fair Value of Financial Assets and Liabilities Commodity Derivatives (Details) - MWh MWh in Millions		Dec. 31, 2019	Dec. 31, 2018
Electric Commodity [Member]
Derivative [Line Items]
Derivative, Nonmonetary Notional Amount	[1]	6.4	5.5

[1] Amounts are not reflective of net positions in the underlying commodities.