Supplemental Balance Sheet Information (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010
Trade Receivables
Billed trade receivables	$ 122.5	$ 82.5
Unbilled trade receivables - Note 1	7.3	1.1
Trade receivables, gross	129.8	83.6
Allowance for doubtful receivables	(0.7)	(0.6)
Trade receivables, net	129.1	83.0
Inventories
Finished products	61.7	53.8
Work in process	60.9	49.6
Raw materials	58.1	50.9
Operating supplies and repairs and maintenance parts	13.9	13.2
Total	194.6	167.5
Prepaid Expenses and Other Current Assets
Current derivative assets - Note 11 and 12	2.0	22.1
Current deferred tax assets	40.6	46.8
Current portion of option premiums paid - Note 11 and 12	1.7	5.6
Short-term restricted cash	7.8	0.9
Prepaid taxes	2.7	1.3
Prepaid expenses	4.1	3.4
Total	58.9	80.1
Property, Plant and Equipment
Land and improvements	23.3	23.3
Buildings	45.8	43.5
Machinery and equipment	351.8	338.0
Construction in progress	18.6	7.7
Active property, plant and equipment, gross	439.5	412.5
Accumulated depreciation	(81.1)	(63.9)
Active property, plant and equipment, net	358.4	348.6
Idled equipment	5.4	5.5
Property, plant, and equipment, net	363.8	354.1
Other Assets
Derivative assets - Note 11 and 12	38.3	50.8
Option premiums paid - Note 11 and 12	0.2	0.6
Restricted cash	10.5	16.3
Long-term income tax receivable	2.8	2.9
Deferred financing costs	8.3	7.7
Available for sale securities	4.6	4.6
Other	0.1	0.1
Total	64.8	83.0
Other Accrued Liabilities
Current derivative liabilities - Note 11 and 12	9.1	8.9
Current portion of option premiums received - Note 11 and 12	1.9	7.0
Current portion of income tax liabilities	1.1	1.1
Taxes payable	2.8	1.8
Accrued annual VEBA contribution	0	2.1
Accrued freight	2.4	1.9
Short-term environmental accrual - Note 10	1.1	1.1
Accrued interest	4.0	2.1
Short-term deferred revenue - Note 1	14.1	10.8
Other	4.5	5.2
Total	41.0	42.0
Long-term Liabilities
Derivative liabilities - Note 11 and 12	49.2	62.2
Option premiums received - Note 11 and 12	0.2	0.3
Income tax liabilities	11.9	12.9
Workers' compensation accruals	17.0	15.9
Long-term environmental accrual - Note 10	20.3	19.1
Long-term asset retirement obligations	3.8	3.8
Long-term deferred revenue - Note 1	6.0	13.2
Deferred compensation liability	4.8	4.9
Other long-term liabilities	2.5	2.4
Total	$ 115.7	$ 134.7