Investments Equity Securities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Equity securities - cost	$ 966.4	$ 632.0
Available-for-sale Securities, Equity Securities	1,190.0	1,004.2
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity securities, OTTI adjustments	0	0
Equity securities - cost	966.4	632.0
Equity securities, gross unrealized gains	224.1	372.7
Equity securities, gross unrealized losses	0.5	0.5
Available-for-sale Securities, Equity Securities	$ 1,190.0	$ 1,004.2