Investment Securities (Net Realized and Unrealized Gains (Losses) After Tax) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Investments, Debt and Equity Securities [Abstract]
Net change in pre-tax unrealized gains (losses) on investments in unconsolidated affiliates	$ (106.4)	$ 62.8	$ (63.6)
Income taxes	8.3	(5.1)	5.1
Net change in unrealized gains (losses) on investments in unconsolidated affiliates, after tax	(98.1)	57.7	(58.5)
Net realized and unrealized foreign currency gains (losses) on investments through OCI	11.3	95.5	(41.7)
Total investments gains (losses) through accumulated other comprehensive income	(86.8)	153.2	(100.2)
Net Realized and Unrealized Gain (Loss) and Foreign Currency Gain (Loss) on Trading Securities Net of Tax	139.8	91.4	56.0
Total investment gains (losses) recorded during the period, after-tax	$ 53.0	$ 244.6	$ (44.2)