Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 131.7		$ 114.7		$ 244.6	$ 294.7
Other comprehensive income (loss):
Foreign currency translation adjustments	6.0		(6.2)		(11.8)	(2.4)
Reclassification of foreign currency translation adjustments into earnings	0.0		0.0		0.0	2.1
Net change in pension and post-retirement liabilities	(2.1)		7.6		(4.5)	10.1
Reclassification of pension and post-retirement benefit losses into earnings	1.4		1.5		4.4	4.4
Pension settlements	0.3		0.0		0.3	60.6
Share of equity method investments other comprehensive income		$ (1.2)		$ 0.0	(1.2)	0.0
Net change in fair value of cash flow hedges	3.2		(3.1)		(3.2)	(2.3)
Reclassification of cash flow hedge losses into earnings	0.4		2.5		5.5	6.9
Other comprehensive income (loss) before taxes	8.0		2.3		(10.5)	79.4
Tax (expense) benefit	(1.2)		0.1		(0.6)	(17.8)
Other comprehensive income (loss), net of tax	6.8		2.4		(11.1)	61.6
Comprehensive income	$ 138.5		$ 117.1		$ 233.5	$ 356.3