Accumulated Other Comprehensive Income (Loss) (Other Comprehensive Income (Loss) Reclassification Adjustments) (Parentheticals) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net holding loss investment securities arising during the period, tax benefit	$ 223.6	$ 5.4	$ 38.2
Reclassification adjustment for net realized gain on investment securities, tax	(60.6)	(104.0)	(49.6)
Non-credit component of OTTI on investments, tax expense (benefit)	(0.9)	(2.4)	0.5
Cash flow hedges, holding gain (loss), tax (expense) benefit	(1.6)	(0.1)	5.3
Net change in unrecognized periodic benefit costs for defined benefit pension and postretirement benefit plans, tax expense (benefit)	(106.8)	(7.1)	81.7
Foreign currency translation adjustment, tax (expense) benefit	(0.6)	(0.3)	(0.2)
Net (loss) gain realized in other comprehensive income, tax benefit (expense)	$ 53.1	$ (108.5)	$ 75.9