Guarantor and Non-Guarantor Financial Statements, Balance Sheets (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 82.6	$ 177.7	$ 212.3	$ 169.5
Short-term investments	30.0	114.0
Receivables:
Trade receivables — net	131.6	129.3
Intercompany receivables	0.0	0.0
Other	4.4	10.9
Inventories	217.3	214.7
Prepaid expenses and other current assets	98.6	178.6
Total current assets	564.5	825.2
Investments in and advances to subsidiaries	0.0	0.0
Property, plant and equipment – net	472.7	454.9
Long-term intercompany receivables	0.0	0.0
Net assets of Union VEBA	0.0	340.1
Deferred tax assets — net	135.7	30.9
Intangible assets – net	30.9	32.1
Goodwill	37.2	37.2
Other assets	22.1	23.3
Total	1,263.1	1,743.7
Current liabilities:
Accounts payable	69.3	81.4
Intercompany payable	0.0	0.0
Accrued salaries, wages and related expenses	38.4	39.6
Other accrued liabilities	61.4	132.8
Current portion of long-term debt	0.0	172.5
Short-term capital leases	0.1	0.1
Total current liabilities	169.2	426.4
Net liabilities of Salaried VEBA	15.9	17.2
Deferred tax liabilities	0.8	0.9
Long-term intercompany payable	0.0	0.0
Long-term liabilities	86.0	58.3
Long-term debt	218.9	225.0
Total liabilities	490.8	727.8
Total stockholders’ equity	772.3	1,015.9
Total	1,263.1	1,743.7
Parent
Current assets:
Cash and cash equivalents	0.0	0.0	0.0	5.0
Short-term investments	0.0	0.0
Receivables:
Trade receivables — net	0.0	0.0
Intercompany receivables	29.2	204.2
Other	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.1	85.1
Total current assets	29.3	289.3
Investments in and advances to subsidiaries	1,057.2	1,209.2
Property, plant and equipment – net	0.0	0.0
Long-term intercompany receivables	0.0	0.0
Net assets of Union VEBA		0.0
Deferred tax assets — net	0.0	0.0
Intangible assets – net	0.0	0.0
Goodwill	0.0	0.0
Other assets	3.7	4.4
Total	1,090.2	1,502.9
Current liabilities:
Accounts payable	0.7	1.3
Intercompany payable	92.3	0.0
Accrued salaries, wages and related expenses	0.0	0.0
Other accrued liabilities	6.0	88.2
Current portion of long-term debt		172.5
Short-term capital leases	0.0	0.0
Total current liabilities	99.0	262.0
Net liabilities of Salaried VEBA	0.0	0.0
Deferred tax liabilities	0.0	0.0
Long-term intercompany payable	0.0	0.0
Long-term liabilities	0.0	0.0
Long-term debt	218.9	225.0
Total liabilities	317.9	487.0
Total stockholders’ equity	772.3	1,015.9
Total	1,090.2	1,502.9
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	79.6	175.3	208.6	157.7
Short-term investments	30.0	114.0
Receivables:
Trade receivables — net	127.8	126.1
Intercompany receivables	96.8	4.0
Other	2.1	5.6
Inventories	213.7	208.0
Prepaid expenses and other current assets	98.1	93.1
Total current assets	648.1	726.1
Investments in and advances to subsidiaries	32.3	32.5
Property, plant and equipment – net	444.2	437.4
Long-term intercompany receivables	0.0	0.0
Net assets of Union VEBA		340.1
Deferred tax assets — net	128.6	23.8
Intangible assets – net	30.9	32.1
Goodwill	37.2	37.2
Other assets	18.3	18.8
Total	1,339.6	1,648.0
Current liabilities:
Accounts payable	64.1	73.8
Intercompany payable	42.6	221.3
Accrued salaries, wages and related expenses	35.5	36.5
Other accrued liabilities	55.6	43.8
Current portion of long-term debt		0.0
Short-term capital leases	0.1	0.1
Total current liabilities	197.9	375.5
Net liabilities of Salaried VEBA	15.9	17.2
Deferred tax liabilities	0.0	0.0
Long-term intercompany payable	2.4	15.9
Long-term liabilities	80.9	50.3
Long-term debt	0.0	0.0
Total liabilities	297.1	458.9
Total stockholders’ equity	1,042.5	1,189.1
Total	1,339.6	1,648.0
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	3.0	2.4	3.7	6.8
Short-term investments	0.0	0.0
Receivables:
Trade receivables — net	3.8	3.2
Intercompany receivables	2.6	0.9
Other	2.3	5.3
Inventories	6.0	7.6
Prepaid expenses and other current assets	1.3	0.4
Total current assets	19.0	19.8
Investments in and advances to subsidiaries	0.0	0.0
Property, plant and equipment – net	28.5	17.5
Long-term intercompany receivables	2.4	15.9
Net assets of Union VEBA		0.0
Deferred tax assets — net	0.0	0.0
Intangible assets – net	0.0	0.0
Goodwill	0.0	0.0
Other assets	0.1	0.1
Total	50.0	53.3
Current liabilities:
Accounts payable	4.5	6.3
Intercompany payable	3.8	3.3
Accrued salaries, wages and related expenses	2.9	3.1
Other accrued liabilities	0.7	0.8
Current portion of long-term debt		0.0
Short-term capital leases	0.0	0.0
Total current liabilities	11.9	13.5
Net liabilities of Salaried VEBA	0.0	0.0
Deferred tax liabilities	0.8	0.9
Long-term intercompany payable	0.0	0.0
Long-term liabilities	5.1	8.0
Long-term debt	0.0	0.0
Total liabilities	17.8	22.4
Total stockholders’ equity	32.2	30.9
Total	50.0	53.3
Consolidating Adjustments
Current assets:
Cash and cash equivalents	0.0	0.0	$ 0.0	$ 0.0
Short-term investments	0.0	0.0
Receivables:
Trade receivables — net	0.0	0.0
Intercompany receivables	(128.6)	(209.1)
Other	0.0	0.0
Inventories	(2.4)	(0.9)
Prepaid expenses and other current assets	(0.9)	0.0
Total current assets	(131.9)	(210.0)
Investments in and advances to subsidiaries	(1,089.5)	(1,241.7)
Property, plant and equipment – net	0.0	0.0
Long-term intercompany receivables	(2.4)	(15.9)
Net assets of Union VEBA		0.0
Deferred tax assets — net	7.1	7.1
Intangible assets – net	0.0	0.0
Goodwill	0.0	0.0
Other assets	0.0	0.0
Total	(1,216.7)	(1,460.5)
Current liabilities:
Accounts payable	0.0	0.0
Intercompany payable	(138.7)	(224.6)
Accrued salaries, wages and related expenses	0.0	0.0
Other accrued liabilities	(0.9)	0.0
Current portion of long-term debt		0.0
Short-term capital leases	0.0	0.0
Total current liabilities	(139.6)	(224.6)
Net liabilities of Salaried VEBA	0.0	0.0
Deferred tax liabilities	0.0	0.0
Long-term intercompany payable	(2.4)	(15.9)
Long-term liabilities	0.0	0.0
Long-term debt	0.0	0.0
Total liabilities	(142.0)	(240.5)
Total stockholders’ equity	(1,074.7)	(1,220.0)
Total	$ (1,216.7)	$ (1,460.5)