Accumulated Other Comprehensive Income (Loss) - Summary (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2021		Jun. 30, 2020
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		$ 3,583.9	[1]	$ 1,577.3	[2]
Other comprehensive income (loss) before reclassifications		(34.8)		(22.4)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax		1.9		0.8
Balance at end of period		3,648.6		1,380.1	[2]
Total
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period		(90.6)		(20.3)
Balance at end of period		(123.5)		(41.9)
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	[2]	30.1		4.8
Other comprehensive income (loss) before reclassifications		(34.5)		(21.0)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax		0.0		0.0
Balance at end of period		(4.4)		(16.2)	[2]
Defined Benefit Pension Plans
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	[2]	(120.3)		(24.0)
Other comprehensive income (loss) before reclassifications		0.0		0.0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax		0.8		(0.1)
Balance at end of period		(119.5)		(24.1)	[2]
Derivative Financial Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	[2]	(0.4)		(1.1)
Other comprehensive income (loss) before reclassifications		(0.3)		(1.4)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax		1.1		0.9
Balance at end of period		$ 0.4		$ (1.6)	[2]

[1] See discussion in Note 1 - Basis of Presentation for further detail regarding the elimination of the International lag reporting.

[2] See discussion in Note 1 - Basis of Presentation for further detail regarding the elimination of the International lag reporting.