Operations and Significant Accounting Policies - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) MW	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Non-Controlling Interest Details [Line Items]
Goodwill \| $	$ 154.9		$ 154.9		$ 154.9
Net Loss Attributable to Non-Controlling Interest \| $	(16.3)	$ (6.9)	$ (47.7)	$ (43.5)
Revision of Prior Period, Error Correction, Adjustment
Non-Controlling Interest Details [Line Items]
Net Loss Attributable to Non-Controlling Interest \| $	$ 5.7				$ 3.6
Glen Ullin Energy Center
Non-Controlling Interest Details [Line Items]
Generating capacity subject to tax equity financing			106
South Peak
Non-Controlling Interest Details [Line Items]
Generating capacity subject to tax equity financing			80
Diamond Spring
Non-Controlling Interest Details [Line Items]
Generating capacity subject to tax equity financing			303
Caddo
Non-Controlling Interest Details [Line Items]
Generating capacity subject to tax equity financing			303
Nobles 2
Non-Controlling Interest Details [Line Items]
Generating capacity subject to tax equity financing			250