Guarantor and Non-Guarantor Financial Statements, Balance Sheets (Details) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents		$ 70.7	$ 72.5	$ 220.9	$ 177.7
Short-term investments		10.0	30.0
Receivables:
Trade receivables – net		138.8	116.7
Intercompany receivables		0.0	0.0
Other		8.6	6.1
Inventories		210.6	219.6
Prepaid expenses and other current assets1	[1]	9.1	56.7
Total current assets		447.8	501.6
Investments in and advances to subsidiaries		0.0	0.0
Property, plant and equipment – net		504.5	495.4
Long-term intercompany receivables		0.0	0.0
Deferred tax assets – net	[1],[2]	197.5	163.3
Intangible assets – net		30.1	30.5
Goodwill		37.2	37.2
Other assets1	[1]	19.5	19.6
Total		1,236.6	1,247.6
Current liabilities:
Accounts payable		70.2	76.7
Intercompany payable		0.0	0.0
Accrued salaries, wages and related expenses		33.9	39.8
Other accrued liabilities		56.5	52.7
Short-term capital leases		0.1	0.1
Total current liabilities		160.7	169.3
Net liabilities of Salaried VEBA		18.7	19.0
Deferred tax liabilities		2.1	2.1
Long-term intercompany payable		0.0	0.0
Long-term liabilities		72.5	87.5
Long-term debt1	[1]	194.8	194.6
Total liabilities		448.8	472.5
Total stockholders' equity		787.8	775.1
Total		1,236.6	1,247.6
Parent
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		93.6	0.0
Other		0.0	0.0
Inventories		0.0	0.0
Prepaid expenses and other current assets1		0.1	0.2
Total current assets		93.7	0.2
Investments in and advances to subsidiaries		912.8	1,077.2
Property, plant and equipment – net		0.0	0.0
Long-term intercompany receivables		0.0	0.0
Deferred tax assets – net		0.0	0.0
Intangible assets – net		0.0	0.0
Goodwill		0.0	0.0
Other assets1		0.0	0.0
Total		1,006.5	1,077.4
Current liabilities:
Accounts payable		0.6	0.5
Intercompany payable		17.9	106.5
Accrued salaries, wages and related expenses		0.0	0.0
Other accrued liabilities		5.4	1.4
Short-term capital leases		0.0	0.0
Total current liabilities		23.9	108.4
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 debt1		194.8	194.6
Total liabilities		218.7	303.0
Total stockholders' equity		787.8	774.4
Total		1,006.5	1,077.4
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents		69.1	72.2	218.9	175.3
Short-term investments		10.0	30.0
Receivables:
Trade receivables – net		134.0	114.0
Intercompany receivables		23.1	111.2
Other		5.9	3.8
Inventories		208.3	216.3
Prepaid expenses and other current assets1		8.5	56.2
Total current assets		458.9	603.7
Investments in and advances to subsidiaries		32.0	31.4
Property, plant and equipment – net		473.1	464.3
Long-term intercompany receivables		0.0	0.0
Deferred tax assets – net		190.5	156.3
Intangible assets – net		30.1	30.5
Goodwill		37.2	37.2
Other assets1		19.4	19.5
Total		1,241.2	1,342.9
Current liabilities:
Accounts payable		64.6	73.6
Intercompany payable		99.3	14.8
Accrued salaries, wages and related expenses		32.4	38.3
Other accrued liabilities		51.3	52.3
Short-term capital leases		0.1	0.1
Total current liabilities		247.7	179.1
Net liabilities of Salaried VEBA		18.7	19.0
Deferred tax liabilities		0.0	0.0
Long-term intercompany payable		3.9	3.1
Long-term liabilities		66.2	81.3
Long-term debt1		0.0	0.0
Total liabilities		336.5	282.5
Total stockholders' equity		904.7	1,060.4
Total		1,241.2	1,342.9
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents		1.6	0.3	2.0	2.4
Short-term investments		0.0	0.0
Receivables:
Trade receivables – net		4.8	2.7
Intercompany receivables		1.3	1.1
Other		2.7	2.3
Inventories		5.8	6.6
Prepaid expenses and other current assets1		0.8	1.7
Total current assets		17.0	14.7
Investments in and advances to subsidiaries		0.0	0.0
Property, plant and equipment – net		31.4	31.1
Long-term intercompany receivables		3.9	3.1
Deferred tax assets – net		0.0	0.0
Intangible assets – net		0.0	0.0
Goodwill		0.0	0.0
Other assets1		0.1	0.1
Total		52.4	49.0
Current liabilities:
Accounts payable		5.0	2.6
Intercompany payable		4.5	4.0
Accrued salaries, wages and related expenses		1.5	1.5
Other accrued liabilities		0.2	0.4
Short-term capital leases		0.0	0.0
Total current liabilities		11.2	8.5
Net liabilities of Salaried VEBA		0.0	0.0
Deferred tax liabilities		2.1	2.1
Long-term intercompany payable		0.0	0.0
Long-term liabilities		6.3	6.2
Long-term debt1		0.0	0.0
Total liabilities		19.6	16.8
Total stockholders' equity		32.8	32.2
Total		52.4	49.0
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		(118.0)	(112.3)
Other		0.0	0.0
Inventories		(3.5)	(3.3)
Prepaid expenses and other current assets1		(0.3)	(1.4)
Total current assets		(121.8)	(117.0)
Investments in and advances to subsidiaries		(944.8)	(1,108.6)
Property, plant and equipment – net		0.0	0.0
Long-term intercompany receivables		(3.9)	(3.1)
Deferred tax assets – net		7.0	7.0
Intangible assets – net		0.0	0.0
Goodwill		0.0	0.0
Other assets1		0.0	0.0
Total		(1,063.5)	(1,221.7)
Current liabilities:
Accounts payable		0.0	0.0
Intercompany payable		(121.7)	(125.3)
Accrued salaries, wages and related expenses		0.0	0.0
Other accrued liabilities		(0.4)	(1.4)
Short-term capital leases		0.0	0.0
Total current liabilities		(122.1)	(126.7)
Net liabilities of Salaried VEBA		0.0	0.0
Deferred tax liabilities		0.0	0.0
Long-term intercompany payable		(3.9)	(3.1)
Long-term liabilities		0.0	0.0
Long-term debt1		0.0	0.0
Total liabilities		(126.0)	(129.8)
Total stockholders' equity		(937.5)	(1,091.9)
Total		$ (1,063.5)	$ (1,221.7)

[1] See Note 1 for discussion of our adoption of ASU 2015-03, ASU 2015-15 and ASU 2015-17 (as defined in Note 1).

[2] See Note 4 and Note 6 for discussion of our adoption of ASU 2016-09 (as defined in Note 1).