Schedule of Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	$ (502.3)	$ (82.4)	$ (814.2)	$ 127.5
Cumulative Effect of New Accounting Principle in Period of Adoption					$ (17.5)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	262.8	(186.7)	580.0	(372.3)
Reclassification from Accumulated Other Comprehensive Income or Loss	(3.0)	(7.1)	(8.3)	(13.9)
Total Other Comprehensive Income (Loss)	259.8	(193.8)	571.7	(386.2)
Balance at End of Period	(242.5)	(276.2)	(242.5)	(276.2)
Net Unrealized Gain (Loss) on Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	(0.1)	356.1	(312.4)	607.8
Cumulative Effect of New Accounting Principle in Period of Adoption					(17.5)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	280.6	(131.7)	586.0	(366.5)
Reclassification from Accumulated Other Comprehensive Income or Loss	6.4	0.1	13.3	0.7
Total Other Comprehensive Income (Loss)	287.0	(131.6)	599.3	(365.8)
Balance at End of Period	286.9	224.5	286.9	224.5
Net Gain on Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	230.1	273.5	250.6	282.3
Cumulative Effect of New Accounting Principle in Period of Adoption					0.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	0.9	4.8	(3.8)	7.7
Reclassification from Accumulated Other Comprehensive Income or Loss	(13.0)	(11.5)	(28.8)	(23.2)
Total Other Comprehensive Income (Loss)	(12.1)	(6.7)	(32.6)	(15.5)
Balance at End of Period	218.0	266.8	218.0	266.8
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	(287.9)	(207.0)	(305.2)	(254.5)
Cumulative Effect of New Accounting Principle in Period of Adoption					0.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(19.7)	(61.8)	(2.4)	(14.3)
Reclassification from Accumulated Other Comprehensive Income or Loss	0.0	0.0	0.0	0.0
Total Other Comprehensive Income (Loss)	(19.7)	(61.8)	(2.4)	(14.3)
Balance at End of Period	(307.6)	(268.8)	(307.6)	(268.8)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	(444.4)	(505.0)	(447.2)	(508.1)
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 0.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	1.0	2.0	0.2	0.8
Reclassification from Accumulated Other Comprehensive Income or Loss	3.6	4.3	7.2	8.6
Total Other Comprehensive Income (Loss)	4.6	6.3	7.4	9.4
Balance at End of Period	$ (439.8)	$ (498.7)	$ (439.8)	$ (498.7)