Goodwill and Intangibles - Intangible Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Period of amortization	5 years
Operating revenues
Amortization to be recorded in the next five years
2022	$ 8.5
2023	8.4
2024	8.4
2025	8.4
2026	8.4
Other operation and maintenance
Amortization to be recorded in the next five years
2022	0.2
2023	0.2
2024	0.2
2025	0.2
2026	0.2
WECI
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	99.8	$ 88.4
Accumulated Amortization	(9.1)	(1.6)
Net Carrying Amount	90.7	86.8
WECI | PPAs
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	87.9	76.1
Accumulated Amortization	(6.5)	0.0
Net Carrying Amount	81.4	76.1
WECI | Proxy revenue swap
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	7.2	7.2
Accumulated Amortization	(2.1)	(1.3)
Net Carrying Amount	5.1	5.9
WECI | Interconnection agreements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	4.7	5.1
Accumulated Amortization	(0.5)	(0.3)
Net Carrying Amount	$ 4.2	$ 4.8
Blooming Grove Wind Energy Center LLC, Tatanka Ridge Wind, LLC, and Jayhawk Wind, LLC | PPAs
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	11 years
Upstream Wind Energy LLC | Proxy revenue swap
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	7 years
Length of proxy revenue contract, in years	10 years
Tatanka Ridge Wind LLC and Bishop Hill Energy III LLC | Interconnection agreements
Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	19 years