Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 132.6	$ 215.5	$ 265.3
Other comprehensive income (loss), net of tax:
Change in unrealized losses on debt securities	199.9	198.0	(780.9)
Change in foreign currency translation adjustment	(46.1)	17.2	(42.2)
Change in pension benefit adjustment	5.6	(2.1)	46.6
Total other comprehensive income (loss), net of tax	159.4	213.1	(776.5)
Comprehensive income (loss)	292.0	428.6	(511.2)
Less: Comprehensive income (loss) attributable to noncontrolling interests	1.5	(1.3)	2.3
Comprehensive income (loss) attributable to the Company	$ 290.5	$ 429.9	$ (513.5)