Investments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 security	Sep. 30, 2013	Sep. 30, 2014 security	Sep. 30, 2013	Dec. 31, 2013 security
Investments [Abstract]
Gross gains on investments	$ 0.1	$ 7.1	$ 0.4	$ 9.9
Gross losses on investments	0.1	0.1	0.2	0.2
Proceeds from sale of investment securities	$ 0.6	$ 12.5	$ 14.9	$ 30.2
Number of debt security positions	46		46		84