v3.26.1
Accumulated other comprehensive income or loss (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Changes in AOCI, net of tax        
Beginning balance $ 5,588.7 $ 6,098.2 $ 5,565.0 $ 5,956.7
Income tax effect 5.0 17.6 0.8 25.3
Ending balance 5,630.2 6,285.9 5,630.2 6,285.9
AOCI        
Changes in AOCI, net of tax        
Beginning balance (43.7) (117.7) (16.9) (184.0)
Unrealized gain (loss) (14.7) 91.9 (35.2) 136.6
Reclassification of (gain) loss into earnings (1.8) (2.2) (3.9) 11.7
Income tax effect 5.0 17.6 0.8 25.3
Ending balance (55.2) (10.4) (55.2) (10.4)
Foreign currency translation        
Changes in AOCI, net of tax        
Beginning balance (56.9) (131.5) (31.0) (177.4)
Unrealized gain (loss) (15.7) 90.1 (37.0) 127.9
Reclassification of (gain) loss into earnings 0.0 0.0 (0.2) 0.0
Income tax effect 4.8 17.6 0.4 25.7
Ending balance (67.8) (23.8) (67.8) (23.8)
Derivative instruments        
Changes in AOCI, net of tax        
Beginning balance 0.0 0.1 0.0 0.2
Unrealized gain (loss) 1.8 2.2 3.7 5.5
Reclassification of (gain) loss into earnings (1.8) (2.2) (3.7) (5.6)
Income tax effect 0.0 0.0 0.0 0.0
Ending balance 0.0 0.1 0.0 0.1
Defined benefit plans        
Changes in AOCI, net of tax        
Beginning balance 13.2 13.7 14.1 (6.8)
Unrealized gain (loss) (0.8) (0.4) (1.9) 3.2
Reclassification of (gain) loss into earnings 0.0 0.0 0.0 17.3
Income tax effect 0.2 0.0 0.4 (0.4)
Ending balance $ 12.6 $ 13.3 $ 12.6 $ 13.3