Unrestricted Subsidiaries - Income statement information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Schedule of Equity Method Investments
Sales	$ 1,100.4	$ 1,149.4	$ 3,239.9	$ 3,204.5
Cost of sales	1,095.5	887.9	3,092.7	2,774.9
Gross profit (loss)	4.9	261.5	147.2	429.6
Operating costs and expenses:
General and administrative	40.2	40.2	101.0	103.0
Other operating expense	(6.9)	4.1	(17.1)	(4.1)
Operating income (loss)	(57.1)	213.0	(14.6)	281.1
Other income (expense):
Interest expense	(57.7)	(58.7)	(175.3)	(163.7)
Gain (loss) on derivative instruments	15.2	(54.3)	9.6	(14.5)
Other income	(0.3)	0.6	0.7	0.1
Total other expense	(42.8)	(112.7)	(165.3)	(183.6)
Net income (loss)	(100.6)	99.8	(181.3)	96.1
Unrestricted Subsidiaries
Schedule of Equity Method Investments
Sales	177.7	184.6	510.9	431.4
Cost of sales	180.6	175.8	543.8	483.0
Gross profit (loss)	(2.9)	8.8	(32.9)	(51.6)
Operating costs and expenses:
General and administrative	6.9	5.8	20.3	15.1
Other operating expense	(4.0)	(0.2)	(6.8)	(4.0)
Operating income (loss)	(13.8)	2.8	(60.0)	(70.7)
Other income (expense):
Interest expense	(25.9)	(22.7)	(72.4)	(59.5)
Gain (loss) on derivative instruments	(1.6)	(4.6)	4.3	(3.2)
Other income		0.7	0.6	0.7
Total other expense	(27.5)	(26.6)	(67.5)	(62.0)
Net income (loss)	$ (41.3)	$ (23.8)	$ (127.5)	$ (132.7)