Summary of Significant Accounting Policies Accumulated Other Comprehensive Income (Loss) Reclassifications out of AOCI (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	$ 0.3	$ 0	$ 0.2	$ (1.6)
Amounts Reclassified from accumulated other comprehensive income (loss)	(0.3)	0	(0.2)	3.6
Amounts Reclassified from Accumulated OCI, Net of Tax and Noncontrolling Interest	(1.4)		(3.3)
Commodity Contract [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	(0.6)		(0.4)
Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	(0.1)		(0.3)
Derivative [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax	(0.7)		(0.7)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	(0.3)		(0.3)
Amounts Reclassified from accumulated other comprehensive income (loss)	(0.4)		(0.4)
Postretirement Benefit Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax	(0.9)		(2.5)
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	0.8		2.2
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax	(0.1)		(0.3)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax	0		(0.1)
Amounts reclassified from accumulated other comprehensive income (loss)	(0.1)		(0.2)
Pension Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax	(1.5)		(4.6)
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	0		0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax	(1.5)		(4.6)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax	(0.6)		(1.8)
Amounts reclassified from accumulated other comprehensive income (loss)	(0.9)		(2.8)
Amortization of Defined Benefit Pension Items, Amount Reclassified from Accumulated OCI, Noncontrolling Interest	0		(0.1)
Amounts Reclassified from Accumulated OCI, Net of Tax and Noncontrolling Interest	$ (0.9)		$ (2.7)