Derivatives (Summary of Derivative Income Expense) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (loss) on Derivative, Net			$ 2.9	$ 0
Loss on derivatives activity	1.6	0	2.9	0
Commodity Swap
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Gain (loss) on Derivative, Net	1.3		2.0
Change in fair value of derivatives	0.3		0.9
Loss on derivatives activity	$ 1.6		$ 2.9