Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	$ 222.1	$ 327.2	$ 374.2	$ 37.3
Other Comprehensive Income (Loss) Before Reclassifications	(104.5)	161.0	(297.8)	426.5
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	3.7	10.6	(37.5)	(13.8)
Net Other Comprehensive Income (Loss)	(108.2)	150.4	(260.3)	440.3
Balance at End of Period	113.9	477.6	113.9	477.6
Net Unrealized Gain on Securities
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	911.4	963.1	1,067.7	615.9
Other Comprehensive Income (Loss) Before Reclassifications	(79.3)	141.3	(295.1)	441.7
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(3.9)	(0.1)	(63.4)	(46.9)
Net Other Comprehensive Income (Loss)	(75.4)	141.4	(231.7)	488.6
Balance at End of Period	836.0	1,104.5	836.0	1,104.5
Net Gain on Hedges
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	77.5	186.2	97.8	187.8
Other Comprehensive Income (Loss) Before Reclassifications	3.9	(12.9)	10.8	15.5
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	11.9	14.6	39.1	44.6
Net Other Comprehensive Income (Loss)	(8.0)	(27.5)	(28.3)	(29.1)
Balance at End of Period	69.5	158.7	69.5	158.7
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(244.7)	(348.2)	(261.3)	(281.6)
Other Comprehensive Income (Loss) Before Reclassifications	(30.5)	34.5	(13.9)	(32.1)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	0.0	0.0	0.0	0.0
Net Other Comprehensive Income (Loss)	(30.5)	34.5	(13.9)	(32.1)
Balance at End of Period	(275.2)	(313.7)	(275.2)	(313.7)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss)
Balance at Beginning of Year	(522.1)	(473.9)	(530.0)	(484.8)
Other Comprehensive Income (Loss) Before Reclassifications	1.4	(1.9)	0.4	1.4
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(4.3)	(3.9)	(13.2)	(11.5)
Net Other Comprehensive Income (Loss)	5.7	2.0	13.6	12.9
Balance at End of Period	$ (516.4)	$ (471.9)	$ (516.4)	$ (471.9)