Consolidated Condensed Statements of Income (Unaudited) (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]
Franchise fees and gross receipts taxes	$ 27.8	$ 26.7	$ 55.0	$ 52.1