Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Changes in Accumulated Other Comprehensive Income (Loss)
January 1	$ (1,197.6)	$ (1,228.5)
Other comprehensive income (loss) before reclassifications	(30.0)	43.1
Cumulative effect of accounting change		(22.3)
Reclassification from accumulated other comprehensive income (loss)	13.8	10.1
December 31	(1,213.8)	(1,197.6)
Cash Flow Hedge
Changes in Accumulated Other Comprehensive Income (Loss)
January 1	(24.0)	(22.3)
Other comprehensive income (loss) before reclassifications	0.0	0.0
Cumulative effect of accounting change		(5.6)
Reclassification from accumulated other comprehensive income (loss)	3.9	3.9
December 31	(20.1)	(24.0)
Defined Benefit Pension Plans and Postemployment Arrangements
Changes in Accumulated Other Comprehensive Income (Loss)
January 1	(112.1)	(69.3)
Other comprehensive income (loss) before reclassifications	(21.0)	(32.3)
Cumulative effect of accounting change		(16.7)
Reclassification from accumulated other comprehensive income (loss)	9.9	6.2
December 31	(123.2)	(112.1)
Foreign Currency Translation
Changes in Accumulated Other Comprehensive Income (Loss)
January 1	(1,061.5)	(1,136.9)
Other comprehensive income (loss) before reclassifications	(9.0)	75.4
Cumulative effect of accounting change		0.0
Reclassification from accumulated other comprehensive income (loss)	0.0	0.0
December 31	$ (1,070.5)	$ (1,061.5)