Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	$ 374.2	$ 37.3
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(447.2)	(286.0)
Reclassification from Accumulated Other Comprehensive Income or Loss, Current Period, Net of Tax	(48.1)	(31.6)
Total Other Comprehensive Loss	(399.1)	(254.4)
Balance at End of Period	(24.9)	(217.1)
Net Unrealized Gain on Securities
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	1,067.7	615.9
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(447.2)	(263.2)
Reclassification from Accumulated Other Comprehensive Income or Loss, Current Period, Net of Tax	(57.7)	(42.6)
Total Other Comprehensive Loss	(389.5)	(220.6)
Balance at End of Period	678.2	395.3
Net Gain on Hedges
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	97.8	187.8
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(6.8)	37.7
Reclassification from Accumulated Other Comprehensive Income or Loss, Current Period, Net of Tax	13.9	14.9
Total Other Comprehensive Loss	(20.7)	22.8
Balance at End of Period	77.1	210.6
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(261.3)	(281.6)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	7.3	(63.6)
Reclassification from Accumulated Other Comprehensive Income or Loss, Current Period, Net of Tax	0.0	0.0
Total Other Comprehensive Loss	7.3	(63.6)
Balance at End of Period	(254.0)	(345.2)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(530.0)	(484.8)
Other Comprehensive Income (Loss), before Reclassifications, Net of Tax	(0.5)	3.1
Reclassification from Accumulated Other Comprehensive Income or Loss, Current Period, Net of Tax	(4.3)	(3.9)
Total Other Comprehensive Loss	3.8	7.0
Balance at End of Period	$ (526.2)	$ (477.8)