Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	$ (24.9)	$ (217.1)	$ 374.2	$ 37.3
Other Comprehensive Income (Loss) Before Reclassifications	253.9	551.5	(193.3)	265.5
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	6.9	7.2	(41.2)	(24.4)
Net Other Comprehensive Income (Loss)	247.0	544.3	(152.1)	289.9
Balance at End of Period	222.1	327.2	222.1	327.2
Net Unrealized Gain on Securities
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	678.2	395.3	1,067.7	615.9
Other Comprehensive Income (Loss) Before Reclassifications	231.4	563.6	(215.8)	300.4
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(1.8)	(4.2)	(59.5)	(46.8)
Net Other Comprehensive Income (Loss)	233.2	567.8	(156.3)	347.2
Balance at End of Period	911.4	963.1	911.4	963.1
Net Gain on Hedges
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	77.1	210.6	97.8	187.8
Other Comprehensive Income (Loss) Before Reclassifications	13.7	(9.3)	6.9	28.4
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	13.3	15.1	27.2	30.0
Net Other Comprehensive Income (Loss)	0.4	(24.4)	(20.3)	(1.6)
Balance at End of Period	77.5	186.2	77.5	186.2
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(254.0)	(345.2)	(261.3)	(281.6)
Other Comprehensive Income (Loss) Before Reclassifications	9.3	(3.0)	16.6	(66.6)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	0.0	0.0	0.0	0.0
Net Other Comprehensive Income (Loss)	9.3	(3.0)	16.6	(66.6)
Balance at End of Period	(244.7)	(348.2)	(244.7)	(348.2)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(526.2)	(477.8)	(530.0)	(484.8)
Other Comprehensive Income (Loss) Before Reclassifications	(0.5)	0.2	(1.0)	3.3
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(4.6)	(3.7)	(8.9)	(7.6)
Net Other Comprehensive Income (Loss)	4.1	3.9	7.9	10.9
Balance at End of Period	$ (522.1)	$ (473.9)	$ (522.1)	$ (473.9)