v3.26.1
Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance $ 26,618.2 $ 27,030.7 $ 28,728.2 $ 26,486.9
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)     (28.9) 163.2
Amounts reclassified from accumulated other comprehensive income (loss)     (2.2) (2.1)
Income tax benefit (expense)     4.1 (10.2)
Other comprehensive income (loss), net of tax (4.5) 120.2 (27.0) 150.9
Ending balance 26,520.4 27,739.0 26,520.4 27,739.0
Accumulated Other Comprehensive Income (Loss)        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance 59.4 (74.8) 81.9 (105.5)
Ending balance 54.9 45.4 54.9 45.4
Investment Securities        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance     0.0 (0.3)
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)     (0.1) 0.1
Amounts reclassified from accumulated other comprehensive income (loss)     0.0 0.0
Income tax benefit (expense)     0.0 0.0
Other comprehensive income (loss), net of tax     (0.1) 0.1
Ending balance (0.1) (0.2) (0.1) (0.2)
Defined Benefit Plans        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance     0.3 (14.1)
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)     (2.2) (1.2)
Amounts reclassified from accumulated other comprehensive income (loss)     (0.1) (0.1)
Income tax benefit (expense)     0.5 0.3
Other comprehensive income (loss), net of tax     (1.8) (1.0)
Ending balance (1.5) (15.1) (1.5) (15.1)
Derivative Investments        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance     56.2 59.3
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)     0.0 0.0
Amounts reclassified from accumulated other comprehensive income (loss)     (2.1) (2.0)
Income tax benefit (expense)     0.5 0.5
Other comprehensive income (loss), net of tax     (1.6) (1.5)
Ending balance 54.6 57.8 54.6 57.8
Foreign Currency Translation        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance     25.4 (150.4)
Other comprehensive income (loss) before reclassifications and income tax benefit (expense)     (26.6) 164.3
Amounts reclassified from accumulated other comprehensive income (loss)     0.0 0.0
Income tax benefit (expense)     3.1 (11.0)
Other comprehensive income (loss), net of tax     (23.5) 153.3
Ending balance $ 1.9 $ 2.9 $ 1.9 $ 2.9