Condensed Guarantor and Non-Guarantor Financial Statements, Balance Sheets (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents		$ 72.9	$ 72.5	$ 82.6	$ 82.6	$ 177.7
Short-term investments		201.0	30.0
Receivables:
Trade receivables – net		142.2	116.7
Intercompany receivables		0.0	0.0
Other		7.3	6.1
Inventories		223.6	219.6
Prepaid expenses and other current assets	[1]	10.9	56.7
Total current assets		657.9	501.6
Investments in and advances to subsidiaries		0.0	0.0
Property, plant and equipment – net		518.6	495.4
Long-term intercompany loans receivable		0.0	0.0
Deferred tax assets – net	[1],[2]	170.9	163.3
Intangible assets – net		26.7	30.5
Goodwill		37.2	37.2
Other assets	[1]	22.1	19.6
Total		1,433.4	1,247.6
Current liabilities:
Accounts payable		69.6	76.7
Intercompany loans payable		0.0	0.0
Accrued salaries, wages and related expenses		42.8	39.8
Other accrued liabilities		46.7	52.7
Short-term capital leases		0.1	0.1
Total current liabilities		159.2	169.3
Net liabilities of Salaried VEBA		18.2	19.0
Deferred tax liabilities		2.2	2.1
Long-term intercompany loans payable		0.0	0.0
Long-term liabilities		71.2	87.5
Long-term debt	[1]	368.5	194.6
Total liabilities		619.3	472.5
Total stockholders' equity		814.1	775.1
Total		1,433.4	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		(82.8)	(112.3)
Other		0.0	0.0
Inventories		(3.8)	(3.3)
Prepaid expenses and other current assets		(0.1)	(1.4)
Total current assets		(86.7)	(117.0)
Investments in and advances to subsidiaries		(1,019.7)	(1,108.6)
Property, plant and equipment – net		0.0	0.0
Long-term intercompany loans receivable		(135.2)	(3.1)
Deferred tax assets – net		6.9	7.0
Intangible assets – net		0.0	0.0
Goodwill		0.0	0.0
Other assets		0.0	0.0
Total		(1,234.7)	(1,221.7)
Current liabilities:
Accounts payable		0.0	0.0
Intercompany loans payable		(82.8)	(125.3)
Accrued salaries, wages and related expenses		0.0	0.0
Other accrued liabilities		(11.6)	(1.4)
Short-term capital leases		0.0	0.0
Total current liabilities		(94.4)	(126.7)
Net liabilities of Salaried VEBA		0.0	0.0
Deferred tax liabilities		0.0	0.0
Long-term intercompany loans payable		(135.2)	(3.1)
Long-term liabilities		0.0	0.0
Long-term debt		0.0	0.0
Total liabilities		(229.6)	(129.8)
Total stockholders' equity		(1,005.1)	(1,091.9)
Total		(1,234.7)	(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 assets		0.2	0.2
Total current assets		82.3	0.2
Investments in and advances to subsidiaries		986.3	1,077.2
Property, plant and equipment – net		0.0	0.0
Long-term intercompany loans receivable		123.5	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		1,192.1	1,077.4
Current liabilities:
Accounts payable		1.0	0.5
Intercompany loans payable		0.0	106.5
Accrued salaries, wages and related expenses		0.0	0.0
Other accrued liabilities		8.5	1.4
Short-term capital leases		0.0	0.0
Total current liabilities		9.5	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		368.5	194.6
Total liabilities		378.0	303.0
Total stockholders' equity		814.1	774.4
Total		1,192.1	1,077.4
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents		69.2	72.2	79.6		175.3
Short-term investments		201.0	30.0
Receivables:
Trade receivables – net		138.0	114.0
Intercompany receivables		0.1	111.2
Other		5.6	3.8
Inventories		221.3	216.3
Prepaid expenses and other current assets		10.4	56.2
Total current assets		645.6	603.7
Investments in and advances to subsidiaries		33.4	31.4
Property, plant and equipment – net		487.0	464.3
Long-term intercompany loans receivable		4.4	0.0
Deferred tax assets – net		164.0	156.3
Intangible assets – net		26.7	30.5
Goodwill		37.2	37.2
Other assets		22.0	19.5
Total		1,420.3	1,342.9
Current liabilities:
Accounts payable		62.9	73.6
Intercompany loans payable		82.7	14.8
Accrued salaries, wages and related expenses		40.6	38.3
Other accrued liabilities		49.2	52.3
Short-term capital leases		0.1	0.1
Total current liabilities		235.5	179.1
Net liabilities of Salaried VEBA		18.2	19.0
Deferred tax liabilities		0.0	0.0
Long-term intercompany loans payable		130.8	3.1
Long-term liabilities		65.2	81.3
Long-term debt		0.0	0.0
Total liabilities		449.7	282.5
Total stockholders' equity		970.6	1,060.4
Total		1,420.3	1,342.9
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents		3.7	0.3	$ 3.0		$ 2.4
Short-term investments		0.0	0.0
Receivables:
Trade receivables – net		4.2	2.7
Intercompany receivables		0.6	1.1
Other		1.7	2.3
Inventories		6.1	6.6
Prepaid expenses and other current assets		0.4	1.7
Total current assets		16.7	14.7
Investments in and advances to subsidiaries		0.0	0.0
Property, plant and equipment – net		31.6	31.1
Long-term intercompany loans receivable		7.3	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		55.7	49.0
Current liabilities:
Accounts payable		5.7	2.6
Intercompany loans payable		0.1	4.0
Accrued salaries, wages and related expenses		2.2	1.5
Other accrued liabilities		0.6	0.4
Short-term capital leases		0.0	0.0
Total current liabilities		8.6	8.5
Net liabilities of Salaried VEBA		0.0	0.0
Deferred tax liabilities		2.2	2.1
Long-term intercompany loans payable		4.4	0.0
Long-term liabilities		6.0	6.2
Long-term debt		0.0	0.0
Total liabilities		21.2	16.8
Total stockholders' equity		34.5	32.2
Total		$ 55.7	$ 49.0

[1] See Note 1 for discussion of our adoption of ASU 2015-03 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).