Other Income (Expense) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Other Income and Expenses [Abstract]
AFUDC - Equity	$ 2.5	$ 4.2	$ 5.8
Investment and Other Income (Expense)	1.9	0.4	(4.0)
Total Other Income	$ 4.4	$ 4.6	$ 1.8