Comprehensive Income (Loss) (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
Schedule of Accumulated Comprehensive Income [Line Items]
Balance at beginning of period	$ 4.7		$ 2.4		$ 4.7		$ 3.5
Other comprehensive income (loss):
Foreign currency translation gain (loss)	(0.1)		0.4		(0.1)		(0.7)
Balance at end of period	4.6		2.8		4.6		2.8
Cash flow hedges
Balance at beginning of period	17.5		24.8		18.3		31.7
Other comprehensive income (loss):
Gains (losses) arising in period	(8.8)		(6.7)		(6.9)		(9.7)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	0		0		0		0
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	(8.8)		(6.7)		(6.9)		(9.7)
Reclassification of losses (gains) to net income (loss):
Reclassification of losses (gains) to net income (loss)	(1.3)		(10.7)		(4.0)		(14.6)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	0		0		0		0
Net amount of reclassification of losses (gains) to net income (loss)	(1.3)		(10.7)		(4.0)		(14.6)
Total other comprehensive income (loss), net of tax	(10.1)		(17.4)		(10.9)		(24.3)
Balance at end of period	7.4		7.4		7.4		7.4
Unrealized holding gains (losses) on securities
Balance at beginning of period	0.4		0.4		0.4		0.3
Other comprehensive income (loss):
Unrealized holding gains (losses) arising in period	0		0.1		0		0.2
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	0		0		0		0
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	0		0.1		0		0.2
Balance at end of period	0.4		0.5		0.4		0.5
Pension and OPEB plans
Balance at beginning of period	276.6		(46.2)		300.0		(34.4)
Other comprehensive income (loss):
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	0		0		(5.3)		0
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, before Reclassification Adjustments, Tax	0		0		0		0
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax	0		0		(5.3)		0
Reclassification to net income (loss):
Prior service costs (credits)	(17.2)		(19.1)		(34.5)		(38.2)
Actuarial (gains) losses	0.2		7.1		(0.6)		14.4
Subtotal - pension and OPEB plans, reclassification to net income (loss)	(17.0)		(12.0)		(35.1)		(23.8)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax	0		0		0		0
Amount of reclassification to net income (loss), net of tax	(17.0)		(12.0)		(35.1)		(23.8)
Total other comprehensive income (loss), net of tax	(17.0)		(12.0)		(40.4)		(23.8)
Balance at end of period	259.6		(58.2)		259.6		(58.2)
Sales [Member] | Hot Roll Carbon Steel Coils [Member]
Reclassification of losses (gains) to net income (loss):
Reclassification of losses (gains) to net income (loss)	0	[1]	0	[1]	0	[1]	(0.4)	[1]
Cost of Products Sold [Member] | Other Commodity Contracts [Member]
Reclassification of losses (gains) to net income (loss):
Reclassification of losses (gains) to net income (loss)	(1.3)	[2]	(10.7)	[2]	(4.0)	[2]	(14.2)	[2]
Pension and OPEB Expense (Income) [Member]
Reclassification to net income (loss):
Prior service costs (credits)	(17.2)	[3]	(19.1)	[3]	(34.5)	[3]	(38.2)	[3]
Actuarial (gains) losses	$ 0.2	[3]	$ 7.1	[3]	$ (0.6)	[3]	$ 14.4	[3]

[1] Amounts are included in net sales on the Condensed Consolidated Statements of Operations.

[2] Amounts are included in cost of products sold on the Condensed Consolidated Statements of Operations.

[3] Amounts are included in pension and OPEB expense (income) on the Condensed Consolidated Statements of Operations.