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Equity Investments - Investment in Nobles 2 (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2022 USD ($) MW	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) MW	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Investment in Nobles 2 [Line Items]
Equity Investment Balance		$ 320.3		$ 320.3		$ 318.0
Cash Investments				5.1	$ 17.4
Equity Earnings		2.3	$ 4.4	13.1	14.3
Net Loss Attributable to Non-Controlling Interest		$ (6.9)	$ (3.5)	$ (43.5)	$ (18.1)
Nobles 2 [Member]
Investment in Nobles 2 [Line Items]
Ownership Percentage		49.00%		49.00%
Equity Investment Balance		$ 159.0		$ 159.0		$ 163.5
Distributed Earnings				(3.8)
Equity Earnings	[1]			(0.7)
Net Loss Attributable to Non-Controlling Interest				$ 7.5
Wind Turbine Generators [Member] | Tenaska [Member] | Minnesota Power [Member] | Tenaska PPA [Member]
Investment in Nobles 2 [Line Items]
Generating Capacity Counterparty Owned (MW) | MW		250		250
Long-term Contract for Purchase of Electric Power, Term of Contract (Years)				20 years
[1] The Company also recorded net loss attributable to non-controlling interest of $7.5 million related to its investment in Nobles 2.

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