Loss per share - Calculation of Loss per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings per share [abstract]
Net loss	$ (35.2)	$ (28.1)	$ (74.6)	$ (38.2)
Weighted average number of ordinary shares, basic (in shares)	177.2	168.6	176.7	168.4
Loss per common share - basic (in dollars per share)	$ (0.20)	$ (0.17)	$ (0.42)	$ (0.23)
Loss per common share - diluted (in dollars per share)	$ (0.20)	$ (0.17)	$ (0.42)	$ (0.23)

The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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- References

No definition available.

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- Definition

The profit (loss) from continuing and discontinued operations attributable to owners of the parent. [Refer: Profit (loss)]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

+ References

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