Other Income (Expense) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other Income (Expense) [Abstract]
AFUDC–Equity	$ 0.7	$ 2.0	$ 1.6	$ 3.8
Gain on Sale of Available-for-sale Securities	0.1	0.2	0.1	0.2
Other Expense	(0.1)	(0.3)		(0.1)
Investments and Other Income			0.1
Total Other Income	$ 0.7	$ 1.9	$ 1.8	$ 3.9