CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income	$ 171.5	$ 167.2	$ 263.5	$ 252.7
Other comprehensive income (loss), net of tax
Deferred commodity contracts hedging losses reclassified in net income, net of tax of $0.1, $0.2, $0.5 and $0.5, respectively	0.3	0.5	1.0	1.0
Other comprehensive income (loss), net of tax	0.3	0.5	1.0	1.0
Comprehensive income (loss)	$ 171.8	$ 167.7	$ 264.5	$ 253.7