Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Statement of Comprehensive Income [Abstract]
Net income	$ 74.8	$ 46.7
Other comprehensive income (loss), net of tax:
Change in unrealized gains (losses) on debt securities	92.3	(50.6)
Change in foreign currency translation adjustment	3.9	(14.5)
Change in pension benefit adjustment	0.4	0.4
Total other comprehensive income (loss), net of tax	96.6	(64.7)
Comprehensive income (loss)	171.4	(18.0)
Less: Comprehensive income attributable to noncontrolling interests	0.6	0.0
Comprehensive income (loss) attributable to the Company	$ 170.8	$ (18.0)