Financial Instruments, Risk Management and Fair Value Measurements - Derivatives in Cash Flow Hedging Relationships (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 544.0	$ 489.6
Unrealized hedging gains, net of tax	(1.8)	1.3
Reclassification of deferred hedging gains, net of tax (1)		(0.4)
Other comprehensive (loss)/income, net of tax	(1.8)	0.9
Ending balance	$ 540.8	508.6
Total Foreign Exchange Contracts
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(1.2)
Unrealized hedging gains, net of tax		0.3
Reclassification of deferred hedging gains, net of tax (1)		(0.4)
Other comprehensive (loss)/income, net of tax		(0.1)
Ending balance		$ (1.3)