Other Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Income and Expenses [Abstract]
AFUDC–Equity	$ 3.3	$ 7.8	$ 4.6
Gain on Sale of Available-for-sale Securities	0.1	0.2	2.2
Investments and Other Income	1.3	0.6	2.5
Total Other Income	$ 4.7	$ 8.6	$ 9.3