Accumulated other comprehensive income or (loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Changes in AOCI
Beginning balance	$ (43.2)	$ 21.7	$ (85.9)
Unrealized gain (loss)	(21.0)	(56.5)	99.1
Reclassification of (gain) loss into earnings	(8.4)	3.6	(1.1)
Income tax expense (benefit)	(27.7)	(12.0)	9.6
Ending balance	(100.3)	(43.2)	21.7
Foreign currency translation
Changes in AOCI
Beginning balance	(19.2)	51.8	(62.3)
Unrealized gain (loss)	(102.0)	(62.8)	106.4
Reclassification of (gain) loss into earnings	0.0	0.0	0.0
Income tax expense (benefit)	(10.1)	(8.2)	7.7
Ending balance	(131.3)	(19.2)	51.8
Derivative instruments
Changes in AOCI
Beginning balance	0.4	(1.0)	(0.5)
Unrealized gain (loss)	33.1	(1.6)	1.0
Reclassification of (gain) loss into earnings	(7.4)	3.5	(1.7)
Income tax expense (benefit)	(6.2)	(0.5)	0.2
Ending balance	19.9	0.4	(1.0)
Defined benefit plans
Changes in AOCI
Beginning balance	(24.4)	(29.1)	(23.1)
Unrealized gain (loss)	47.9	7.9	(8.3)
Reclassification of (gain) loss into earnings	(1.0)	0.1	0.6
Income tax expense (benefit)	(11.4)	(3.3)	1.7
Ending balance	$ 11.1	$ (24.4)	$ (29.1)