CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net income	$ 79.0	$ 73.4	$ 92.0	$ 85.5
Other comprehensive income (loss), net of tax
Deferred commodity contracts hedging gains (losses), net of tax of $0.1, $0.3, $0.4 and $0.3, respectively	0.2	0.5	0.7	0.5
Other comprehensive income (loss), net of tax	0.2	0.5	0.7	0.5
Comprehensive income (loss)	$ 79.2	$ 73.9	$ 92.7	$ 86.0