Investment Securities (Net Realized and Unrealized Gains (Losses) After Tax) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Investments, Debt and Equity Securities [Abstract]
Accumulated Other Comprehensive Income (Loss) Equity in Unrealized Gains (Losses) from Investments in Unconsolidated Affiliates before Tax	$ 62.8	$ (63.6)	$ 72.7
Income taxes	(5.1)	5.1	0.8
Net change in unrealized gains (losses) on investments in unconsolidated affiliates, after tax	57.7	(58.5)	73.5
Other Comprehensive Income, Foreign Currency Transaction and Translation Adjustment, Unrealized Gain (Loss) on Investments, Net of Tax Period Increase (Decrease)	95.5	(41.7)	107.9
Total investments gains (losses) through accumulated other comprehensive income	153.2	(100.2)	181.4
Net Realized and Unrealized Gain (Loss) and Foreign Currency Gain (Loss) on Trading Securities Net of Tax	91.4	56.0	56.1
Total investment gains (losses) recorded during the period, after-tax	$ 244.6	$ (44.2)	$ 237.5