Accumulated Other Comprehensive Loss - Changes in accumulated other comprehensive loss (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (9.6)						$ (9.6)		$ 11.0
Changes in accumulated other comprehensive loss
Other comprehensive loss, net of tax, before reclassifications							(7.3)
Amounts reclassified from AOCI, net of tax expense of $4.2, $—, and $4.2							(13.0)
Reclassification from AOCI, Current Period, Tax							4.2
Less: noncontrolling interest	16.9	$ 10.9	$ (7.5)	$ (0.2)	$ (5.0)	$ 14.4	20.3	$ 9.2
Other comprehensive income (loss)							(20.6)
Unrealized gains/(losses) on derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(8.3)						(8.3)		12.4
Changes in accumulated other comprehensive loss
Other comprehensive loss, net of tax, before reclassifications							(7.3)
Amounts reclassified from AOCI, net of tax expense of $4.2, $—, and $4.2							(13.1)
Reclassification from AOCI, Current Period, Tax							4.2
Other comprehensive income (loss)							(20.7)
Net actuarial gains/(losses) of defined benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(1.3)						(1.3)		(1.4)
Changes in accumulated other comprehensive loss
Other comprehensive loss, net of tax, before reclassifications							0.0
Amounts reclassified from AOCI, net of tax expense of $4.2, $—, and $4.2							0.1
Reclassification from AOCI, Current Period, Tax							0.0
Other comprehensive income (loss)							0.1
Accumulated Gain (Loss), Net, Cash Flow Hedge, Noncontrolling Interest [Member]
Changes in accumulated other comprehensive loss
Less: noncontrolling interest							(0.3)
Noncontrolling Interest [Member]
Changes in accumulated other comprehensive loss
Less: noncontrolling interest	(0.1)	(0.1)	(0.1)	(0.1)	(0.1)	7.4	(0.3)
Accumulated other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(9.6)						$ (9.6)		$ 11.0
Changes in accumulated other comprehensive loss
Less: noncontrolling interest	$ 17.0	$ 11.0	$ (7.4)	$ (0.1)	$ (4.9)	$ 7.0