Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	$ 0.4	$ 200.7	$ (51.0)	$ 16.1
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	111.6	143.9	170.1	325.9
Reclassification from Accumulated Other Comprehensive Income or Loss	(7.1)	(4.8)	(14.2)	(2.2)
Net Other Comprehensive Income (Loss)	104.5	139.1	155.9	323.7
Balance at End of Period	104.9	339.8	104.9	339.8
Net Unrealized Gain on Securities
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	483.0	438.4	440.6	204.3
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	76.6	222.0	121.3	445.8
Reclassification from Accumulated Other Comprehensive Income or Loss	(1.4)	0.7	(3.7)	11.0
Net Other Comprehensive Income (Loss)	75.2	222.7	117.6	456.8
Balance at End of Period	558.2	661.1	558.2	661.1
Net Gain on Cash Flow Hedges
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	316.8	351.8	327.5	378.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(3.4)	(0.2)	(6.1)	(16.1)
Reclassification from Accumulated Other Comprehensive Income or Loss	(8.9)	(8.0)	(16.9)	(18.3)
Net Other Comprehensive Income (Loss)	(12.3)	(8.2)	(23.0)	(34.4)
Balance at End of Period	304.5	343.6	304.5	343.6
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	(336.9)	(200.0)	(354.0)	(173.6)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	39.8	(79.4)	56.9	(105.8)
Reclassification from Accumulated Other Comprehensive Income or Loss	0.0	0.0	0.0	0.0
Net Other Comprehensive Income (Loss)	39.8	(79.4)	56.9	(105.8)
Balance at End of Period	(297.1)	(279.4)	(297.1)	(279.4)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	(462.5)	(389.5)	(465.1)	(392.6)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(1.4)	1.5	(2.0)	2.0
Reclassification from Accumulated Other Comprehensive Income or Loss	3.2	2.5	6.4	5.1
Net Other Comprehensive Income (Loss)	1.8	4.0	4.4	7.1
Balance at End of Period	$ (460.7)	$ (385.5)	$ (460.7)	$ (385.5)