Accumulated Other Comprehensive Income (Loss) - Reclasses Out Of AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022		Dec. 31, 2021
Accumulated Other Comprehensive Income [Abstract]
Beginning Balance	$ 570.2	$ 252.6		$ 202.5
Other comprehensive income	42.2	201.0		89.5
Acquisitions of noncontrolling interests	(0.6)	7.8	[1]
Ending Balance	520.2	570.2		252.6
Benefit plan adjustments
Accumulated Other Comprehensive Income [Abstract]
Beginning Balance	(290.7)	(474.0)		(614.8)
Other comprehensive income (loss) before reclassifications	(13.1)	151.9		92.5
Amounts reclassified from accumulated other comprehensive loss to net income (loss)	1.6	31.4		48.3
Other comprehensive income	(11.5)	183.3		140.8
Ending Balance	(302.2)	(290.7)		(474.0)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income [Abstract]
Beginning Balance	(433.8)	(425.7)		(363.2)
Other comprehensive income (loss) before reclassifications	69.6	(3.8)		(59.4)
Amounts reclassified from accumulated other comprehensive loss to net income (loss)	(4.0)	(4.4)		(3.1)
Other comprehensive income	65.6	(8.2)		(62.5)
Acquisitions of noncontrolling interests		0.1
Ending Balance	(368.2)	(433.8)		(425.7)
Gains (Losses) on Available-for-Sale Securities
Accumulated Other Comprehensive Income [Abstract]
Beginning Balance	(0.6)	(0.1)		0.0
Other comprehensive income (loss) before reclassifications	(4.5)	(0.7)		(0.1)
Amounts reclassified from accumulated other comprehensive loss to net income (loss)	3.3	0.2		0.0
Other comprehensive income	(1.2)	(0.5)		(0.1)
Ending Balance	(1.8)	(0.6)		(0.1)
Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income [Abstract]
Beginning Balance	24.6	(8.1)		(22.0)
Other comprehensive income (loss) before reclassifications	1.1	24.4		5.6
Amounts reclassified from accumulated other comprehensive loss to net income (loss)	(9.5)	8.3		8.3
Other comprehensive income	(8.4)	32.7		13.9
Ending Balance	16.2	24.6		(8.1)
AOCI Attributable to Parent
Accumulated Other Comprehensive Income [Abstract]
Beginning Balance	(700.5)	(907.9)		(1,000.0)
Other comprehensive income (loss) before reclassifications	53.1	171.8		38.6
Amounts reclassified from accumulated other comprehensive loss to net income (loss)	(8.6)	35.5		53.5
Other comprehensive income	44.5	207.3		92.1
Acquisitions of noncontrolling interests	0.0	0.1	[1]
Ending Balance	$ (656.0)	$ (700.5)		$ (907.9)

[1] This amount represents the impact of transactions in which we acquired or disposed of noncontrolling ownership interests in certain companies where we had an existing controlling interest prior to and after the related acquisition or disposal transactions.