Supplemental Balance Sheet Information (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Trade Receivables
Billed trade receivables	$ 114.4	$ 82.5
Unbilled trade receivables - Note 1	5.3	1.1
Trade receivables, gross	119.7	83.6
Allowance for doubtful receivables	(0.6)	(0.6)
Trade receivables, net	119.1	83.0
Inventories
Finished products	55.7	53.8
Work in process	64.1	49.6
Raw materials	44.8	50.9
Operating supplies and repairs and maintenance parts	13.6	13.2
Total	178.2	167.5
Prepaid Expenses and Other Current Assets
Current derivative assets - Note 11	14.2	22.1
Current deferred tax assets	46.7	46.8
Current portion of option premiums paid - Note 11	3.0	5.6
Short-term restricted cash	7.9	0.9
Prepaid taxes	2.1	1.3
Prepaid expenses	4.9	3.4
Total	78.8	80.1
Property, Plant and Equipment
Land and improvements	23.3	23.3
Buildings	45.8	43.5
Machinery and equipment	346.5	338.0
Construction in progress	14.8	7.7
Active property, plant and equipment, gross	430.4	412.5
Accumulated depreciation	(75.4)	(63.9)
Active property, plant and equipment, net	355.0	348.6
Idled equipment	5.4	5.5
Property, plant, and equipment, net	360.4	354.1
Other Assets
Derivative assets - Note 11	56.2	50.8
Option premiums paid - Note 11	0.4	0.6
Restricted cash	9.4	16.3
Long-term income tax receivable	3.0	2.9
Deferred financing costs	6.7	7.7
Available for sale securities	5.0	4.6
Other	0.2	0.1
Total	80.9	83.0
Other Accrued Liabilities
Current derivative liabilities - Note 11	6.3	8.9
Current portion of option premiums received - Note 11	3.6	7.0
Current portion of income tax liabilities	1.2	1.1
Accrued income taxes and taxes payable	3.6	1.8
Accrued annual VEBA contribution	0	2.1
Accrued freight	1.7	1.9
Short-term environmental accrual - Note 10	0.9	1.1
Accrued interest	2.1	2.1
Short-term deferred revenue - Note 1	10.6	10.8
Other	4.4	5.2
Total	34.4	42.0
Long-term Liabilities
Derivative liabilities - Note 11	69.4	62.2
Option premiums received - Note 11	0.2	0.3
Income tax liabilities	13.8	12.9
Workers' compensation accruals	16.9	15.9
Long-term environmental accrual - Note 10	20.9	19.1
Long-term asset retirement obligations	3.8	3.8
Long-term deferred revenue - Note 1	9.0	13.2
Deferred compensation liability	5.1	4.9
Other long-term liabilities	2.7	2.4
Total	$ 141.8	$ 134.7