Supplemental Cash Flow Information - Supplemental Information (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Supplemental cash flow information
Cash paid for interest, net of amount capitalized	$ 785.7	$ 653.4	$ 485.2
Cash paid (received) for income taxes, net	(264.2)	(58.9)	52.4
Cash received for sale of production tax credits to third parties	269.1	75.0
Significant non-cash investing and financing transactions
Accounts payable related to construction costs	285.7	171.3	197.4
Common stock issued for stock-based compensation plans	6.4	0.0	0.0
Increase in receivables related to property damage insurance proceeds	2.3	3.5	0.0
Increase in receivables for corporate-owned life insurance proceeds	5.8	1.4	0.0
Liabilities accrued for software licensing agreement	$ 0.2	$ 0.0	$ 7.4

Future cash outflow to pay for purchases of fixed assets that have occurred.

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