CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Statement of Comprehensive Income [Abstract]
Net Income	$ 457.6	$ 464.9	$ 1,270.9	$ 1,575.7
Other Comprehensive Income (Net of Tax and Reclassifications)
Net Unrealized Gains on Available for Sale Debt Securities	44.3	63.9	161.2	320.7
Net Unrealized Gains (Losses) on Cash Flow Hedges	0.0	0.3	(0.6)	(0.5)
Net Foreign Currency Adjustments	17.6	18.9	14.6	30.5
Net Pension and Other Postretirement Benefit Adjustments	2.2	2.4	3.7	7.7
Other Comprehensive Income	64.1	85.5	178.9	358.4
Comprehensive Income	$ 521.7	$ 550.4	$ 1,449.8	$ 1,934.1