Schedule of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	$ 339.8	$ 3.4	$ 16.1	$ 166.4
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	117.7	25.1	443.7	(132.2)
Reclassification from Accumulated Other Comprehensive Income or Loss	(6.8)	(6.5)	(9.1)	(12.2)
Net Other Comprehensive Income (Loss)	110.9	18.6	434.6	(144.4)
Balance at End of Period	450.7	22.0	450.7	22.0
Net Unrealized Gain on Securities
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	661.1	112.1	204.3	290.3
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	143.0	47.0	588.9	(137.6)
Reclassification from Accumulated Other Comprehensive Income or Loss	(0.9)	(0.5)	10.0	5.9
Net Other Comprehensive Income (Loss)	142.1	46.5	598.9	(131.7)
Balance at End of Period	803.2	158.6	803.2	158.6
Net Gain on Cash Flow Hedges
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	343.6	391.7	378.0	391.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	0.1	21.3	(16.0)	37.9
Reclassification from Accumulated Other Comprehensive Income or Loss	(8.5)	(7.9)	(26.8)	(23.8)
Net Other Comprehensive Income (Loss)	(8.4)	13.4	(42.8)	14.1
Balance at End of Period	335.2	405.1	335.2	405.1
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	(279.4)	(102.5)	(173.6)	(113.4)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(25.8)	(44.1)	(131.6)	(33.2)
Reclassification from Accumulated Other Comprehensive Income or Loss	0.0	0.0	0.0	0.0
Net Other Comprehensive Income (Loss)	(25.8)	(44.1)	(131.6)	(33.2)
Balance at End of Period	(305.2)	(146.6)	(305.2)	(146.6)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income, Net of Tax
Balance at Beginning of Period	(385.5)	(397.9)	(392.6)	(401.5)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	0.4	0.9	2.4	0.7
Reclassification from Accumulated Other Comprehensive Income or Loss	2.6	1.9	7.7	5.7
Net Other Comprehensive Income (Loss)	3.0	2.8	10.1	6.4
Balance at End of Period	$ (382.5)	$ (395.1)	$ (382.5)	$ (395.1)