Commitments and Contingencies ARO Phantom (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019		Dec. 31, 2018
Asset Retirement Obligations [Line Items]
Amounts Settled	$ 1.6	[1]	$ 0.0	[2]
Amounts Incurred	16.0	[3]	0.0	[2]
Electric Plant Steam Production Asbestos
Asset Retirement Obligations [Line Items]
Amounts Settled	1.6	[1]	0.0
Amounts Incurred	0.0	[3]	0.0
Electric Plant Distribution
Asset Retirement Obligations [Line Items]
Amounts Settled	0.0	[1]	0.0
Amounts Incurred	0.0	[3]	0.0
Electric Plant Other Sources
Asset Retirement Obligations [Line Items]
Amounts Settled	0.0	[1]	0.0
Amounts Incurred	$ 0.0	[3]	$ 0.0

[1] Amounts settled related to asbestos abatement projects.

[2] There were no ARO amounts incurred or settled in 2018.

[3] Amounts incurred related to the Hale wind farm placed in service in 2019.