Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	$ (82.4)	$ 0.4	$ 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	(186.7)	111.6	(372.3)	170.1
Reclassification from Accumulated Other Comprehensive Income or Loss	(7.1)	(7.1)	(13.9)	(14.2)
Total Other Comprehensive Income (Loss)	(193.8)	104.5	(386.2)	155.9
Balance at End of Period	(276.2)	104.9	(276.2)	104.9
Net Unrealized Gain on Securities
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	356.1	483.0	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	(131.7)	76.6	(366.5)	121.3
Reclassification from Accumulated Other Comprehensive Income or Loss	0.1	(1.4)	0.7	(3.7)
Total Other Comprehensive Income (Loss)	(131.6)	75.2	(365.8)	117.6
Balance at End of Period	224.5	558.2	224.5	558.2
Net Gain on Hedges
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	273.5	316.8	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	(3.4)	7.7	(6.1)
Reclassification from Accumulated Other Comprehensive Income or Loss	(11.5)	(8.9)	(23.2)	(16.9)
Total Other Comprehensive Income (Loss)	(6.7)	(12.3)	(15.5)	(23.0)
Balance at End of Period	266.8	304.5	266.8	304.5
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	(207.0)	(336.9)	(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	(61.8)	39.8	(14.3)	56.9
Reclassification from Accumulated Other Comprehensive Income or Loss	0.0	0.0	0.0	0.0
Total Other Comprehensive Income (Loss)	(61.8)	39.8	(14.3)	56.9
Balance at End of Period	(268.8)	(297.1)	(268.8)	(297.1)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	(505.0)	(462.5)	(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	2.0	(1.4)	0.8	(2.0)
Reclassification from Accumulated Other Comprehensive Income or Loss	4.3	3.2	8.6	6.4
Total Other Comprehensive Income (Loss)	6.3	1.8	9.4	4.4
Balance at End of Period	$ (498.7)	$ (460.7)	$ (498.7)	$ (460.7)