Acquisitions - Upstream (Details) $ in Millions	1 Months Ended
	Jan. 31, 2019 USD ($) MW	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Feb. 19, 2020 USD ($)
Asset Acquisition - Allocation of Purchase Price to Assets acquired, Liabilities assumed, less Noncontrolling Interest
Current assets		$ 2,656.7	$ 2,083.0
Net property, plant, and equipment		26,982.4	25,707.4
Current liabilities		$ (3,753.0)	$ (4,148.1)
Upstream
Asset Acquisition
Capacity of generation unit | MW	202.5
Number of years Upstream will receive fixed payment	10 years
Upstream | WECI
Asset Acquisition
Ownership interest in generating facility acquired	80.00%
Total purchase price	$ 268.2
Cash and restricted cash acquired	9.2
Additional ownership interest acquired				10.00%
Additional acquisition purchase price				$ 31.0
Asset Acquisition - Allocation of Purchase Price to Assets acquired, Liabilities assumed, less Noncontrolling Interest
Current assets	0.4
Net property, plant, and equipment	341.6
Other long-term assets	14.8
Current liabilities	(4.6)
Long-term liabilities	(15.0)
Noncontrolling interest	(69.0)
Total purchase price	$ 268.2