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Fair value of financial instruments (Details) $ in Millions		3 Months Ended		6 Months Ended
Fair value of financial instruments (Details) $ in Millions	Jul. 15, 2022 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jul. 12, 2022 USD ($) derivative_instrument	Mar. 31, 2022 derivative_instrument	Dec. 31, 2021 USD ($)	Sep. 30, 2021 derivative_instrument	Mar. 31, 2019 derivative_instrument
Debt Securities, Available-for-sale [Line Items]
Other operating income (expense)		$ 2.4	$ 0.5	$ 2.7	$ 3.4
Foreign currency transaction gains (losses)				(13.4)	(5.0)
Interest expense		(32.4)	(28.2)	(60.3)	(55.4)
Subsequent Event
Debt Securities, Available-for-sale [Line Items]
Proceeds from foreign currency derivatives	$ 67.0
Not Designated as Hedging Instrument \| Foreign Exchange Contract
Debt Securities, Available-for-sale [Line Items]
Notional value of nonderivative instruments				$ 476.0
Weighted average maturity				1 month
Not Designated as Hedging Instrument \| Foreign Exchange Contract \| Other operating income (expense)
Debt Securities, Available-for-sale [Line Items]
Gain (loss) on foreign currency contract		14.1	(2.3)	$ 33.0	8.2
Not Designated as Hedging Instrument \| Foreign Exchange Contract \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of derivative instruments		2.6		2.6				$ 1.9
Designated as Hedging Instrument \| Level 2
Debt Securities, Available-for-sale [Line Items]
Interest expense		(0.2)	(1.4)	$ (1.1)	(3.8)
Designated as Hedging Instrument \| Currency Swap
Debt Securities, Available-for-sale [Line Items]
Weighted average maturity				1 year
Notional value of derivative instrument		65.0		$ 65.0
Other operating income (expense)		(5.3)	11.7	6.5	5.6
Foreign currency transaction gains (losses)		(5.3)	11.7	6.5	5.6
Interest expense		(0.3)	(0.5)	(0.7)	(0.8)
Foreign currency derivative instrument gains (losses)		5.0	(12.2)	(7.2)	(6.4)
Designated as Hedging Instrument \| Currency Swap \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of contract, asset position		18.1		$ 18.1				26.3
Designated as Hedging Instrument \| $400 million interest rate swap
Debt Securities, Available-for-sale [Line Items]
Weighted average maturity				9 months 18 days
Notional value of derivative instrument		400.0		$ 400.0
Number of instruments held \| derivative_instrument										10
Designated as Hedging Instrument \| $400 million interest rate swap \| Level 2
Debt Securities, Available-for-sale [Line Items]
Interest expense		(1.8)	(2.5)	(4.2)	(4.9)
Fair value of swap, net		3.7		$ 3.7
Fair value of swap, liability position								13.9
Designated as Hedging Instrument \| $200 million interest rate swap
Debt Securities, Available-for-sale [Line Items]
Weighted average maturity				1 month 6 days
Notional value of derivative instrument		200.0		$ 200.0
Number of instruments held \| derivative_instrument							4
Designated as Hedging Instrument \| $200 million interest rate swap \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of swap, asset position		10.5		$ 10.5
Designated as Hedging Instrument \| $400 million cross currency swap
Debt Securities, Available-for-sale [Line Items]
Weighted average maturity				4 years 8 months 12 days
Notional value of derivative instrument		400.0		$ 400.0
Number of instruments held \| derivative_instrument									10
Designated as Hedging Instrument \| $400 million cross currency swap \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of contract, asset position		52.1		52.1				28.5
Interest expense		(1.6)	$ (1.1)	(3.1)	$ (1.1)
Designated as Hedging Instrument \| $400 million cross currency swap 2022 \| Subsequent Event
Debt Securities, Available-for-sale [Line Items]
Notional value of derivative instrument						$ 400.0
Number of instruments held \| derivative_instrument						9
Designated as Hedging Instrument \| $215 million cross currency swap \| Subsequent Event
Debt Securities, Available-for-sale [Line Items]
Notional value of derivative instrument						$ 215.0
Designated as Hedging Instrument \| $185 million cross currency swap \| Subsequent Event
Debt Securities, Available-for-sale [Line Items]
Notional value of derivative instrument						$ 185.0
Prepaid expenses and other \| Not Designated as Hedging Instrument \| Foreign Exchange Contract \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of derivative instruments		5.9		5.9				3.4
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Debt Securities, Available-for-sale [Line Items]
Fair value of contract, asset position		5.3		5.3				5.8
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Debt Securities, Available-for-sale [Line Items]
Fair value of swap, liability position		2.3		2.3
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Debt Securities, Available-for-sale [Line Items]
Fair value of contract, asset position		6.0		6.0				6.0
Other assets \| Designated as Hedging Instrument \| Currency Swap \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of contract, asset position		12.8		12.8				20.5
Other assets \| Designated as Hedging Instrument \| $400 million interest rate swap \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of swap, liability position		1.4		1.4
Other assets \| Designated as Hedging Instrument \| $400 million cross currency swap \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of contract, asset position		46.1		46.1				22.5
Accrued liabilities \| Not Designated as Hedging Instrument \| Foreign Exchange Contract \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of derivative instruments		3.3		3.3				1.5
Accrued liabilities \| Designated as Hedging Instrument \| $400 million interest rate swap \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of swap, liability position								8.3
Other liabilities \| Designated as Hedging Instrument \| $400 million interest rate swap \| Level 2
Debt Securities, Available-for-sale [Line Items]
Fair value of swap, liability position								5.6
Six hundred million senior unsecured notes
Debt Securities, Available-for-sale [Line Items]
Carrying value		600.0		600.0				600.0
Six hundred million senior unsecured notes \| Level 3
Debt Securities, Available-for-sale [Line Items]
Fair value		520.5		520.5				625.7
Four hundred million senior unsecured notes
Debt Securities, Available-for-sale [Line Items]
Carrying value		400.0		400.0				400.0
Four hundred million senior unsecured notes \| Level 3
Debt Securities, Available-for-sale [Line Items]
Fair value		$ 366.8		$ 366.8				$ 414.8