Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 354.1	$ 374.2	$ 37.3	$ (814.2)
Other Comprehensive Income (Loss) Before Reclassifications	(51.5)	359.4	865.5
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(31.4)	22.5	14.0
Total Other Comprehensive Income (Loss)	(20.1)	336.9	851.5
Net Unrealized Gain (Loss) on Securities
Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	962.2	1,067.7	615.9	(312.4)
Other Comprehensive Income (Loss) Before Reclassifications	(169.9)	405.6	894.1
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(64.4)	(46.2)	(34.2)
Total Other Comprehensive Income (Loss)	(105.5)	451.8	928.3
Net Gain on Hedges
Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	61.8	97.8	187.8	250.6
Other Comprehensive Income (Loss) Before Reclassifications	14.7	(5.7)	(0.2)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	50.7	84.3	62.6
Total Other Comprehensive Income (Loss)	(36.0)	(90.0)	(62.8)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(273.9)	(261.3)	(281.6)	(305.2)
Other Comprehensive Income (Loss) Before Reclassifications	(12.6)	20.3	23.6
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	0.0	0.0	0.0
Total Other Comprehensive Income (Loss)	(12.6)	20.3	23.6
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(396.0)	(530.0)	(484.8)	$ (447.2)
Other Comprehensive Income (Loss) Before Reclassifications	116.3	(60.8)	(52.0)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss	(17.7)	(15.6)	(14.4)
Total Other Comprehensive Income (Loss)	$ 134.0	$ (45.2)	$ (37.6)