Comprehensive Income (Loss) Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Foreign currency translation
Balance at beginning of period	$ 3.5		$ 2.8
Other comprehensive income (loss):
Foreign currency translation gain (loss)	(1.1)		0.8
Balance at end of period	2.4		3.6
Cash flow hedges
Balance at beginning of period	31.7		(10.9)
Other comprehensive income (loss):
Gains (losses) arising in period	(3.0)		(17.0)
Income tax provision (benefit)	0		(6.6)
Gains (losses) arising in period, net of tax	(3.0)		(10.4)
Reclassification of losses (gains) to net income (loss):
Reclassification of losses (gains) to net income (loss)	(3.9)		7.8
Net amount of reclassification of losses (gains) to net income (loss)	(3.9)		4.7
Total other comprehensive income (loss), net of tax	(6.9)		(5.7)
Balance at end of period	24.8		(16.6)
Unrealized holding gains (losses) on securities
Balance at beginning of period	0.3		(0.6)
Other comprehensive income (loss):
Unrealized holding gains (losses) arising in period	0.1		0.7
Income tax provision (benefit)	0		0.3
Unrealized holding gains (losses) arising in period, net of tax	0.1		0.4
Balance at end of period	0.4		(0.2)
Pension and OPEB plans
Balance at beginning of period	(34.4)		11.4
Reclassification to net income (loss):
Prior service costs (credits)	(19.1)		(18.2)
Actuarial (gains) losses	7.3		6.1
Subtotal	(11.8)		(12.1)
Net amount of reclassification to net income (loss)	(11.8)		(7.6)
Balance at end of period	(46.2)		3.8
Sales [Member] | Hot Roll Carbon Steel Coils [Member]
Reclassification of losses (gains) to net income (loss):
Reclassification of losses (gains) to net income (loss)	(0.4)	[1]	0	[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)	(3.5)	[2]	7.8	[2]
Income Tax Provision (Benefit) [Member]
Reclassification of losses (gains) to net income (loss):
Income tax provision (benefit)	0	[3]	3.1	[3]
Reclassification to net income (loss):
Income tax provision (benefit)	0	[3]	(4.5)	[3]
Pension and OPEB Expense (Income) [Member]
Reclassification to net income (loss):
Prior service costs (credits)	19.1	[4]	18.2	[4]
Actuarial (gains) losses	$ 7.3	[4]	$ 6.1	[4]

[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 Income tax provision (benefit) on the Condensed Consolidated Statements of Operations.

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