Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	$ (3,448.3)	$ (5,164.6)
Other Comprehensive Income (Loss) Before Reclassifications	293.1	723.8
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	7.1	(2.3)
Total Other Comprehensive Income	286.0	726.1
Balance at End of Period	(3,162.3)	(4,438.5)
Net Unrealized Gain (Loss) on Securities
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(3,028.4)	4,014.4
Other Comprehensive Income (Loss) Before Reclassifications	823.4	(2,903.8)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	0.2	(10.0)
Total Other Comprehensive Income	823.2	(2,893.8)
Balance at End of Period	(2,205.2)	1,120.6
Effect of Change in Discount Rate Assumptions on the LFPB1
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	313.9	(8,570.7)
Other Comprehensive Income (Loss) Before Reclassifications	(573.9)	3,658.1
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	0.0	0.0
Total Other Comprehensive Income	(573.9)	3,658.1
Balance at End of Period	(260.0)	(4,912.6)
Net Gain on Hedges
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(9.6)	61.8
Other Comprehensive Income (Loss) Before Reclassifications	25.6	0.4
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	8.2	10.8
Total Other Comprehensive Income	17.4	(10.4)
Balance at End of Period	7.8	51.4
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(390.1)	(274.1)
Other Comprehensive Income (Loss) Before Reclassifications	24.7	(32.0)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	0.0	0.0
Total Other Comprehensive Income	24.7	(32.0)
Balance at End of Period	(365.4)	(306.1)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(334.1)	(396.0)
Other Comprehensive Income (Loss) Before Reclassifications	(6.7)	1.1
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(1.3)	(3.1)
Total Other Comprehensive Income	(5.4)	4.2
Balance at End of Period	$ (339.5)	$ (391.8)