v3.25.1
Accumulated Other Comprehensive Income (Loss) - Schedule of Changes in Accumulated Other Comprehensive (Loss) Income (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning Balance $ 1,603.5 $ 1,297.5
Other comprehensive income (loss) before reclassifications 6.3 (10.8)
Amounts reclassified from accumulated other comprehensive income 1.0 (5.2)
Net current-period other comprehensive income (loss) 7.3 (16.0)
Ending Balance 1,638.4 1,404.5
Accumulated Other Comprehensive Income (Loss)    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning Balance 31.7 51.8
Ending Balance 39.0 35.8
Foreign Currency Translation Adjustments    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning Balance (0.4) 0.1
Other comprehensive income (loss) before reclassifications 0.1 (0.1)
Amounts reclassified from accumulated other comprehensive income 0.0 0.0
Net current-period other comprehensive income (loss) 0.1 (0.1)
Ending Balance (0.3) 0.0
Unrealized Holding Gains (Losses) on Securities    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning Balance 31.2 51.1
Other comprehensive income (loss) before reclassifications 6.2 (10.7)
Amounts reclassified from accumulated other comprehensive income 1.0 (5.2)
Net current-period other comprehensive income (loss) 7.2 (15.9)
Ending Balance 38.4 35.2
Defined Benefit Pension Plans    
AOCI Attributable to Parent, Net of Tax [Roll Forward]    
Beginning Balance 0.9 0.6
Other comprehensive income (loss) before reclassifications 0.0 0.0
Amounts reclassified from accumulated other comprehensive income 0.0 0.0
Net current-period other comprehensive income (loss) 0.0 0.0
Ending Balance $ 0.9 $ 0.6