Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	$ (276.2)	$ 104.9	$ 127.5	$ (51.0)
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings			(17.5)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(583.8)	27.3	(956.1)	197.4
Reclassification from Accumulated Other Comprehensive Income or Loss	(8.5)	(7.9)	(22.4)	(22.1)
Total Other Comprehensive Income (Loss)	(592.3)	19.4	(978.5)	175.3
Balance at End of Period	(868.5)	124.3	(868.5)	124.3
Net Unrealized Gain (Loss) on Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	224.5	558.2	607.8	440.6
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings			(17.5)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(564.3)	4.4	(930.8)	125.7
Reclassification from Accumulated Other Comprehensive Income or Loss	(0.9)	(5.2)	(0.2)	(8.9)
Total Other Comprehensive Income (Loss)	(565.2)	(0.8)	(931.0)	116.8
Balance at End of Period	(340.7)	557.4	(340.7)	557.4
Net Gain on Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	266.8	304.5	282.3	327.5
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings			0.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(4.8)	(7.9)	2.9	(14.0)
Reclassification from Accumulated Other Comprehensive Income or Loss	(12.0)	(5.9)	(35.2)	(22.8)
Total Other Comprehensive Income (Loss)	(16.8)	(13.8)	(32.3)	(36.8)
Balance at End of Period	250.0	290.7	250.0	290.7
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	(268.8)	(297.1)	(254.5)	(354.0)
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings			0.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(15.2)	31.8	(29.5)	88.7
Reclassification from Accumulated Other Comprehensive Income or Loss	0.0	0.0	0.0	0.0
Total Other Comprehensive Income (Loss)	(15.2)	31.8	(29.5)	88.7
Balance at End of Period	(284.0)	(265.3)	(284.0)	(265.3)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income (Loss), Net of Tax
Balance at Beginning of Period	(498.7)	(460.7)	(508.1)	(465.1)
Recognition and Measurement of Financial Assets and Financial Liabilities, Reclassification from AOCI to Retained Earnings			0.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	0.5	(1.0)	1.3	(3.0)
Reclassification from Accumulated Other Comprehensive Income or Loss	4.4	3.2	13.0	9.6
Total Other Comprehensive Income (Loss)	4.9	2.2	14.3	6.6
Balance at End of Period	$ (493.8)	$ (458.5)	$ (493.8)	$ (458.5)