Accumulated Other Comprehensive Loss - Rollforward (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	$ 3,542.8
Increase (decrease) before reclassifications	21.5	$ (78.4)	$ (75.0)
Income tax impact, before reclassifications	28.8	11.9	(3.0)
Other comprehensive (loss) income before reclassifications, net of income taxes	50.3	(66.5)	(78.0)
Increase (decrease) reclassified	2.9	0.6	(0.9)
Income tax impact, reclassified	(0.8)	(0.1)	0.3
Amounts reclassified from accumulated other comprehensive (loss) income, net of income taxes	2.1	0.5	(0.6)
Net current period other comprehensive (loss) income, net of income taxes	52.4	(66.0)	(78.6)
Balance, end of period	3,721.0	3,542.8
Foreign Currency Translation Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	(116.4)	(74.3)	10.9
Increase (decrease) before reclassifications	26.0	(46.6)	(85.2)
Income tax impact, before reclassifications	27.9	4.5	0.0
Other comprehensive (loss) income before reclassifications, net of income taxes	53.9	(42.1)	(85.2)
Increase (decrease) reclassified	0.0	0.0	0.0
Income tax impact, reclassified	0.0	0.0	0.0
Amounts reclassified from accumulated other comprehensive (loss) income, net of income taxes	0.0	0.0	0.0
Net current period other comprehensive (loss) income, net of income taxes	53.9	(42.1)	(85.2)
Balance, end of period	(62.5)	(116.4)	(74.3)
Foreign Currency Translation Adjustments | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period			10.9
Foreign Currency Translation Adjustments | Cumulative Effect, Period of Adoption, Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period			0.0
Unrealized Gain (Loss) on Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	0.1	0.0	0.0
Increase (decrease) before reclassifications	(8.4)	0.1	0.0
Income tax impact, before reclassifications	2.0	0.0	0.0
Other comprehensive (loss) income before reclassifications, net of income taxes	(6.4)	0.1	0.0
Increase (decrease) reclassified	0.0	0.0	0.0
Income tax impact, reclassified	0.0	0.0	0.0
Amounts reclassified from accumulated other comprehensive (loss) income, net of income taxes	0.0	0.0	0.0
Net current period other comprehensive (loss) income, net of income taxes	(6.4)	0.1	0.0
Balance, end of period	(6.3)	0.1	0.0
Unrealized Gain (Loss) on Cash Flow Hedges | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period			0.0
Unrealized Gain (Loss) on Cash Flow Hedges | Cumulative Effect, Period of Adoption, Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period			0.0
Unrealized Pension Costs
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	(27.9)	(3.9)	(10.3)
Increase (decrease) before reclassifications	3.9	(31.9)	10.2
Income tax impact, before reclassifications	(1.1)	7.4	(3.0)
Other comprehensive (loss) income before reclassifications, net of income taxes	2.8	(24.5)	7.2
Increase (decrease) reclassified	2.9	0.6	(0.9)
Income tax impact, reclassified	(0.8)	(0.1)	0.3
Amounts reclassified from accumulated other comprehensive (loss) income, net of income taxes	2.1	0.5	(0.6)
Net current period other comprehensive (loss) income, net of income taxes	4.9	(24.0)	6.6
Balance, end of period	(23.0)	(27.9)	(3.9)
Unrealized Pension Costs | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period			(10.5)
Unrealized Pension Costs | Cumulative Effect, Period of Adoption, Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period			(0.2)
Total Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period	(144.2)	(78.2)	0.6
Balance, end of period	$ (91.8)	$ (144.2)	(78.2)
Total Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjusted Balance
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period			0.4
Total Accumulated Other Comprehensive Loss | Cumulative Effect, Period of Adoption, Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance, beginning of period			$ (0.2)