Condensed Guarantor and Non-Guarantor Financial Statements, Balance Sheets (Details) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents		$ 195.3	$ 72.5	$ 54.3	$ 177.7
Short-term investments		72.0	30.0
Receivables:
Trade receivables – net		134.6	116.7
Intercompany receivables		0.0	0.0
Other		8.2	6.1
Inventories		217.5	219.6
Prepaid expenses and other current assets1	[1]	12.8	56.7
Total current assets		640.4	501.6
Investments in and advances to subsidiaries		0.0	0.0
Property, plant and equipment – net		512.7	495.4
Long-term intercompany loans receivable		0.0	0.0
Deferred tax assets – net	[1],[2]	180.9	163.3
Intangible assets – net		29.7	30.5
Goodwill		37.2	37.2
Other assets	[1]	20.7	19.6
Total		1,421.6	1,247.6
Current liabilities:
Accounts payable		72.3	76.7
Intercompany loans payable		0.0	0.0
Accrued salaries, wages and related expenses		36.4	39.8
Other accrued liabilities		44.2	52.7
Short-term capital leases		0.1	0.1
Total current liabilities		153.0	169.3
Net liabilities of Salaried VEBA		18.5	19.0
Deferred tax liabilities		2.2	2.1
Long-term intercompany loans payable		0.0	0.0
Long-term liabilities		71.4	87.5
Long-term debt	[1]	368.2	194.6
Total liabilities		613.3	472.5
Total stockholders' equity		808.3	775.1
Total		1,421.6	1,247.6
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		(82.7)	(112.3)
Other		0.0	0.0
Inventories		(3.6)	(3.3)
Prepaid expenses and other current assets1		(0.4)	(1.4)
Total current assets		(86.7)	(117.0)
Investments in and advances to subsidiaries		(993.6)	(1,108.6)
Property, plant and equipment – net		0.0	0.0
Long-term intercompany loans receivable		(147.9)	(3.1)
Deferred tax assets – net		7.0	7.0
Intangible assets – net		0.0	0.0
Goodwill		0.0	0.0
Other assets		0.0	0.0
Total		(1,221.2)	(1,221.7)
Current liabilities:
Accounts payable		0.0	0.0
Intercompany loans payable		(82.7)	(125.3)
Accrued salaries, wages and related expenses		0.0	0.0
Other accrued liabilities		(9.5)	(1.4)
Short-term capital leases		0.0	0.0
Total current liabilities		(92.2)	(126.7)
Net liabilities of Salaried VEBA		0.0	0.0
Deferred tax liabilities		0.0	0.0
Long-term intercompany loans payable		(147.9)	(3.1)
Long-term liabilities		0.0	0.0
Long-term debt		0.0	0.0
Total liabilities		(240.1)	(129.8)
Total stockholders' equity		(981.1)	(1,091.9)
Total		(1,221.2)	(1,221.7)
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		82.1	0.0
Other		0.0	0.0
Inventories		0.0	0.0
Prepaid expenses and other current assets1		0.2	0.2
Total current assets		82.3	0.2
Investments in and advances to subsidiaries		960.8	1,077.2
Property, plant and equipment – net		0.0	0.0
Long-term intercompany loans receivable		137.6	0.0
Deferred tax assets – net		0.0	0.0
Intangible assets – net		0.0	0.0
Goodwill		0.0	0.0
Other assets		0.0	0.0
Total		1,180.7	1,077.4
Current liabilities:
Accounts payable		1.2	0.5
Intercompany loans payable		0.0	106.5
Accrued salaries, wages and related expenses		0.0	0.0
Other accrued liabilities		3.0	1.4
Short-term capital leases		0.0	0.0
Total current liabilities		4.2	108.4
Net liabilities of Salaried VEBA		0.0	0.0
Deferred tax liabilities		0.0	0.0
Long-term intercompany loans payable		0.0	0.0
Long-term liabilities		0.0	0.0
Long-term debt		368.2	194.6
Total liabilities		372.4	303.0
Total stockholders' equity		808.3	774.4
Total		1,180.7	1,077.4
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents		193.4	72.2	49.8	175.3
Short-term investments		72.0	30.0
Receivables:
Trade receivables – net		130.1	114.0
Intercompany receivables		0.0	111.2
Other		5.0	3.8
Inventories		215.0	216.3
Prepaid expenses and other current assets1		12.2	56.2
Total current assets		627.7	603.7
Investments in and advances to subsidiaries		32.8	31.4
Property, plant and equipment – net		480.9	464.3
Long-term intercompany loans receivable		4.3	0.0
Deferred tax assets – net		173.9	156.3
Intangible assets – net		29.7	30.5
Goodwill		37.2	37.2
Other assets		20.6	19.5
Total		1,407.1	1,342.9
Current liabilities:
Accounts payable		64.4	73.6
Intercompany loans payable		82.7	14.8
Accrued salaries, wages and related expenses		34.5	38.3
Other accrued liabilities		50.6	52.3
Short-term capital leases		0.1	0.1
Total current liabilities		232.3	179.1
Net liabilities of Salaried VEBA		18.5	19.0
Deferred tax liabilities		0.0	0.0
Long-term intercompany loans payable		143.6	3.1
Long-term liabilities		65.1	81.3
Long-term debt		0.0	0.0
Total liabilities		459.5	282.5
Total stockholders' equity		947.6	1,060.4
Total		1,407.1	1,342.9
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents		1.9	0.3	$ 4.5	$ 2.4
Short-term investments		0.0	0.0
Receivables:
Trade receivables – net		4.5	2.7
Intercompany receivables		0.6	1.1
Other		3.2	2.3
Inventories		6.1	6.6
Prepaid expenses and other current assets1		0.8	1.7
Total current assets		17.1	14.7
Investments in and advances to subsidiaries		0.0	0.0
Property, plant and equipment – net		31.8	31.1
Long-term intercompany loans receivable		6.0	3.1
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		55.0	49.0
Current liabilities:
Accounts payable		6.7	2.6
Intercompany loans payable		0.0	4.0
Accrued salaries, wages and related expenses		1.9	1.5
Other accrued liabilities		0.1	0.4
Short-term capital leases		0.0	0.0
Total current liabilities		8.7	8.5
Net liabilities of Salaried VEBA		0.0	0.0
Deferred tax liabilities		2.2	2.1
Long-term intercompany loans payable		4.3	0.0
Long-term liabilities		6.3	6.2
Long-term debt		0.0	0.0
Total liabilities		21.5	16.8
Total stockholders' equity		33.5	32.2
Total		$ 55.0	$ 49.0

[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).