Accumulated Other Comprehensive Income (Parenthenticals) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Unrealized Gains (losses) on Available For Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax effect on other comprehensive income (loss) before reclassifications	$ (44.9)	$ 24.6
Tax effect of reclassification from other comprehensive income	1.2	(1.1)
Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax effect on other comprehensive income (loss) before reclassifications	1.8	(37.9)
Tax effect of reclassification from other comprehensive income	$ 3.5	$ 0.9