Consolidated Condensed Statements of Income (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement [Abstract]
Franchise fees and gross receipts taxes	$ 29.7	$ 31.0	$ 81.8	$ 85.4