Schedule of Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Accumulated Other Comprehensive Income
Balance, Beginning of Period	$ 628.0
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(382.6)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss, Net of Tax	9.6
Total Other Comprehensive Income (Loss)	(373.0)	166.2	110.4
Balance, End of Period	255.0	628.0
Net Unrealized Gain on Securities
Accumulated Other Comprehensive Income
Balance, Beginning of Period	873.5
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	(746.4)
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss, Net of Tax	8.6
Total Other Comprehensive Income (Loss)	(737.8)
Balance, End of Period	135.7
Net Gain on Cash Flow Hedges
Accumulated Other Comprehensive Income
Balance, Beginning of Period	401.6
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	9.7
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss, Net of Tax	(15.0)
Total Other Comprehensive Income (Loss)	(5.3)
Balance, End of Period	396.3
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income
Balance, Beginning of Period	(72.6)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	25.5
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss, Net of Tax	0
Total Other Comprehensive Income (Loss)	25.5
Balance, End of Period	(47.1)
Unrecognized Pension and Postretirement Benefit Costs
Accumulated Other Comprehensive Income
Balance, Beginning of Period	(574.5)
Other Comprehensive Income (Loss) Before Reclassifications, Net of Tax	328.6
Amounts Reclassified from Accumulated Other Comprehensive Income or Loss, Net of Tax	16.0
Total Other Comprehensive Income (Loss)	344.6
Balance, End of Period	$ (229.9)