Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 136.4	$ 110.2	$ 182.4	$ 208.3
Other comprehensive income (loss), net of tax:
Unrealized (losses) gains on debt securities	(79.7)	(266.8)	30.4	(638.4)
Foreign currency translation adjustment	11.2	(24.5)	13.8	(22.2)
Pension benefit adjustment	0.4	1.1	0.7	2.2
Total other comprehensive (loss) income, net of tax	(68.1)	(290.2)	44.9	(658.4)
Comprehensive income (loss)	68.3	(180.0)	227.3	(450.1)
Less: Comprehensive (loss) income attributable to noncontrolling interests	(2.1)	1.4	(2.0)	1.6
Comprehensive income (loss) attributable to the Company	$ 70.4	$ (181.4)	$ 229.3	$ (451.7)