Consolidated Statement of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Comprehensive Income (Loss) [Abstract]
Net Income	$ 32.5		$ 24.4
Other Comprehensive Income (Loss) [Abstract]
Unrealized Gain on Securities, Net of Income Taxes of $- and $0.7	0	[1]	1.0
Unrealized Gain (Loss) on Derivatives, Net of Income Taxes of $- and $(0.1)	0.1	[1]	(0.1)
Defined Benefit Pension and Other Postretirement Benefit Plans, Net of Income Taxes of $0.2 and $0.3	0.3	[1]	0.5
Total Other Comprehensive Income	0.4	[1]	1.4
Comprehensive Income	$ 32.9		$ 25.8

[1] Amounts shown are net of tax.