Guarantor and Non-Guarantor Financial Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010	May 23, 2012
Current assets:
Cash and cash equivalents	$ 177.7				$ 169.5				$ 177.7		$ 169.5		$ 273.4			$ 49.8
Short-term investments	114.0				129.5				114.0		129.5
Receivables:
Trade, less allowance for doubtful receivables	129.3				119.8				129.3		119.8
Intercompany receivables	0				0				0		0
Other	10.9				13.4				10.9		13.4
Inventories	214.7				214.4				214.7		214.4
Prepaid expenses and other current assets	178.6				44.2				178.6		44.2
Total current assets	825.2				690.8				825.2		690.8
Investments in and advances to unconsolidated affiliates	0				0				0		0
Property, plant and equipment — net	454.9				429.3				454.9		429.3
Long-term intercompany receivables	0				0				0		0
Net asset of VEBAs	340.1				406.0				340.1		406.0
Deferred tax assets — net	30.9				69.1				30.9		69.1
Intangible assets — net	32.1				33.7				32.1		33.7
Goodwill	37.2				37.2				37.2		37.2
Other assets	23.3				104.8				23.3		104.8
Total	1,743.7				1,770.9				1,743.7		1,770.9
Current liabilities:
Accounts payable	81.4				62.9				81.4		62.9
Intercompany payable	0				0				0		0
Accrued salaries, wages and related expenses	39.6				42.7				39.6		42.7
Other accrued liabilities	132.8				44.8				132.8		44.8
Current portion of long-term debt	172.5				0				172.5		0
Short-term capital leases	0.1				0.2				0.1		0.2
Total current liabilities	426.4				150.6				426.4		150.6
Net liability of VEBA	17.2				0				17.2		0
Deferred tax liabilities	0.9				1.2				0.9		1.2
Long-term intercompany payable	0				0				0		0
Long-term liabilities	58.3				146.4				58.3		146.4
Long-term debt	225.0				388.5				225.0		388.5
Total liabilities	727.8				686.7				727.8		686.7
Total stockholders’ equity	1,015.9				1,084.2				1,015.9		1,084.2		1,070.8		872.8
Total	1,743.7				1,770.9				1,743.7		1,770.9
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales	338.0	338.9	344.1	335.1	311.3	319.9	328.9	337.4	1,356.1		1,297.5		1,360.1
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	278.7	280.4	275.5	282.9	254.3	259.5	261.5	263.6	1,117.5		1,038.9		1,116.2
Unrealized losses (gains) on derivative instruments	10.4	3.6	(1.6)	(2.0)	(4.1)	(1.5)	4.2	0.7	10.4		(0.7)		(15.2)
Depreciation and amortization									31.1		28.1		26.5
Selling, administrative, research and development and general									81.4		80.4		74.1
Non-cash defined benefit net periodic benefit income									(23.5)		(22.0)		(11.5)
Defined benefit plan, net periodic benefit cost - VEBAs									(23.7)		(22.5)		(11.9)
Total selling, administrative, research and development and general									57.7		57.9		62.2
Other operating charges, net									1.5		0		4.5
Total costs and expenses									1,218.2		1,124.2		1,194.2
Operating (loss) income	26.8	32.6	46.4	32.1	41.6	41.6	40.1	50.0	137.9		173.3		165.9
Interest expense									(37.5)		(35.7)		(29.1)
Other (expense) income:
Other income, net									6.7		5.6		2.8
(Loss) income before income taxes									107.1		143.2		139.6
Income tax provision									(35.3)		(38.4)		(53.8)
Earnings in equity of subsidiaries									0		0		0
Net income	15.6	15.9	24.5	15.8	27.3	25.4	18.6	33.5	71.8		104.8		85.8
Comprehensive (loss) income									(3.6)		110.1		144.8
Cash flows from operating activities:
Net cash (used in) provided by operating activities									124.1		111.7		152.4
Cash flows from investing activities:
Capital expenditures									(59.4)		(70.4)		(44.1)
Payments to Acquire Available-for-sale Securities									93.5		227.8		85.0
Proceeds from disposal of property, plant and equipment									0		0		0.3
Proceeds from disposition of available for sale securities									108.2		183.1		0
Change in restricted cash									0		1.7		6.9
Net cash used in investing activities									(44.7)		(113.4)		(121.9)
Cash flows from financing activities:
Proceeds from issuance of Senior Notes									0	[1]	0	[1]	225.0	[1]
Repayments of capital lease									(0.1)	[1]	(0.1)	[1]	(0.1)	[1]
Repayment of promissory notes									0	[1]	0	[1]	(4.7)	[1]
Cash paid for financing costs									0	[1]	0	[1]	(6.6)	[1]
Repurchase of common stock									(44.1)	[1]	(78.3)	[1]	0	[1]
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0.8	[1]	1.1	[1]	1.3	[1]
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									(2.4)	[1]	(2.5)	[1]	(2.2)	[1]
Cash dividend paid to stockholders									(25.4)	[1]	(23.0)	[1]	(19.6)	[1]
Cash dividend returned to the Company			0.6						0	[1]	0.6	[1]	0	[1]
Intercompany loan									0		0		0
Net cash provided by (used in) financing activities									(71.2)	[1]	(102.2)	[1]	193.1	[1]
Net increase (decrease) in cash and cash equivalents during the period									8.2		(103.9)		223.6
Cash and cash equivalents at beginning of period				169.5				273.4	169.5		273.4		49.8			49.8
Cash and cash equivalents at end of period	177.7				169.5				177.7		169.5		273.4			49.8
Principal amount of notes	225.0				225.0				225.0		225.0
Ownership interest by parent	100.00%								100.00%
Parent
Current assets:
Cash and cash equivalents	0				5.0				0		5.0		5.0			5.0
Short-term investments	0				0				0		0
Receivables:
Trade, less allowance for doubtful receivables	0				0				0		0
Intercompany receivables	204.2				0				204.2		0
Other	0				0				0		0
Inventories	0				0				0		0
Prepaid expenses and other current assets	85.1				0.1				85.1		0.1
Total current assets	289.3				5.1				289.3		5.1
Investments in and advances to unconsolidated affiliates	1,209.2				1,437.9				1,209.2		1,437.9
Property, plant and equipment — net	0				0				0		0
Long-term intercompany receivables	0				31.3				0		31.3
Net asset of VEBAs	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 assets	4.4				86.2				4.4		86.2
Total	1,502.9				1,560.5				1,502.9		1,560.5
Current liabilities:
Accounts payable	1.3				1.1				1.3		1.1
Intercompany payable	0				0				0		0
Accrued salaries, wages and related expenses	0				0				0		0
Other accrued liabilities	88.2				3.5				88.2		3.5
Current portion of long-term debt	172.5								172.5
Short-term capital leases	0				0				0		0
Total current liabilities	262.0				4.6				262.0		4.6
Net liability of VEBA	0								0
Deferred tax liabilities	0				0				0		0
Long-term intercompany payable	0				0				0		0
Long-term liabilities	0				83.2				0		83.2
Long-term debt	225.0				388.5				225.0		388.5
Total liabilities	487.0				476.3				487.0		476.3
Total stockholders’ equity	1,015.9				1,084.2				1,015.9		1,084.2
Total	1,502.9				1,560.5				1,502.9		1,560.5
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales									0		0		0
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items									0		0		0
Unrealized losses (gains) on derivative instruments									0		0		0
Depreciation and amortization									0		0		0
Selling, administrative, research and development and general									4.1		3.8		2.0
Non-cash defined benefit net periodic benefit income									0		0		0
Total selling, administrative, research and development and general									4.1		3.8		2.0
Other operating charges, net									0				0
Total costs and expenses									4.1		3.8		2.0
Operating (loss) income									(4.1)		(3.8)		(2.0)
Interest expense									(37.5)		(36.6)		(28.2)
Other (expense) income:
Other income, net									3.7		3.9		0.8
(Loss) income before income taxes									(37.9)		(36.5)		(29.4)
Income tax provision									0		0		0
Earnings in equity of subsidiaries									109.7		141.3		115.2
Net income									71.8		104.8		85.8
Comprehensive (loss) income									(3.6)		110.1		144.8
Cash flows from operating activities:
Net cash (used in) provided by operating activities									35.6		(29.2)		(17.8)
Cash flows from investing activities:
Capital expenditures									0		0		0
Payments to Acquire Available-for-sale Securities									0		0		0
Proceeds from disposal of property, plant and equipment													0
Proceeds from disposition of available for sale securities									0		0
Change in restricted cash											0		6.9
Net cash used in investing activities									0		0		6.9
Cash flows from financing activities:
Proceeds from issuance of Senior Notes													225.0
Repayments of capital lease									0		0		0
Repayment of promissory notes													0
Cash paid for financing costs													(6.6)
Repurchase of common stock									(44.1)		(78.3)
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0		0		0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									(2.4)		(2.5)		(2.2)
Cash dividend paid to stockholders									(25.4)		(23.0)		(19.6)
Cash dividend returned to the Company											0.6
Intercompany loan									31.3		132.4		(185.7)
Net cash provided by (used in) financing activities									(40.6)		29.2		10.9
Net increase (decrease) in cash and cash equivalents during the period									(5.0)		0		0
Cash and cash equivalents at beginning of period				5.0				5.0	5.0		5.0					5.0
Cash and cash equivalents at end of period	0				5.0				0		5.0		5.0			5.0
Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	175.3				157.7				175.3		157.7		266.0			43.0
Short-term investments	114.0				129.5				114.0		129.5
Receivables:
Trade, less allowance for doubtful receivables	126.1				117.7				126.1		117.7
Intercompany receivables	4.0				0.1				4.0		0.1
Other	5.6				5.3				5.6		5.3
Inventories	208.0				208.6				208.0		208.6
Prepaid expenses and other current assets	93.1				43.7				93.1		43.7
Total current assets	726.1				662.6				726.1		662.6
Investments in and advances to unconsolidated affiliates	32.5				26.5				32.5		26.5
Property, plant and equipment — net	437.4				414.0				437.4		414.0
Long-term intercompany receivables	0				1.6				0		1.6
Net asset of VEBAs	340.1				406.0				340.1		406.0
Deferred tax assets — net	23.8				60.2				23.8		60.2
Intangible assets — net	32.1				33.7				32.1		33.7
Goodwill	37.2				37.2				37.2		37.2
Other assets	18.8				18.5				18.8		18.5
Total	1,648.0				1,660.3				1,648.0		1,660.3
Current liabilities:
Accounts payable	73.8				56.3				73.8		56.3
Intercompany payable	221.3				13.9				221.3		13.9
Accrued salaries, wages and related expenses	36.5				39.3				36.5		39.3
Other accrued liabilities	43.8				39.9				43.8		39.9
Current portion of long-term debt	0								0
Short-term capital leases	0.1				0.2				0.1		0.2
Total current liabilities	375.5				149.6				375.5		149.6
Net liability of VEBA	17.2								17.2
Deferred tax liabilities	0				0				0		0
Long-term intercompany payable	15.9				40.7				15.9		40.7
Long-term liabilities	50.3				52.0				50.3		52.0
Long-term debt	0				0				0		0
Total liabilities	458.9				242.3				458.9		242.3
Total stockholders’ equity	1,189.1				1,418.0				1,189.1		1,418.0
Total	1,648.0				1,660.3				1,648.0		1,660.3
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales									1,323.4		1,275.2		1,326.0
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items									1,098.3		1,026.0		1,090.0
Unrealized losses (gains) on derivative instruments									10.4		(0.7)		(15.2)
Depreciation and amortization									30.0		27.0		25.5
Selling, administrative, research and development and general									69.7		70.1		69.6
Non-cash defined benefit net periodic benefit income									(23.7)				(11.9)
Total selling, administrative, research and development and general									46.0		47.6		57.7
Other operating charges, net									1.5				4.5
Total costs and expenses									1,186.2		1,099.9		1,162.5
Operating (loss) income									137.2		175.3		163.5
Interest expense									(0.6)		0.5		(1.0)
Other (expense) income:
Other income, net									3.2		2.0		1.5
(Loss) income before income taxes									139.8		177.8		164.0
Income tax provision									(50.2)		(68.1)		(62.6)
Earnings in equity of subsidiaries									6.0		17.6		2.6
Net income									95.6		127.3		104.0
Comprehensive (loss) income									19.9		131.6		164.0
Cash flows from operating activities:
Net cash (used in) provided by operating activities									81.8		131.7		164.3
Cash flows from investing activities:
Capital expenditures									(56.4)		(66.5)		(42.6)
Payments to Acquire Available-for-sale Securities									93.5		227.8		85.0
Proceeds from disposal of property, plant and equipment													0.3
Proceeds from disposition of available for sale securities									108.2		183.1
Change in restricted cash											0.7		0.4
Net cash used in investing activities									(41.7)		(110.5)		(126.9)
Cash flows from financing activities:
Proceeds from issuance of Senior Notes													0
Repayments of capital lease									(0.1)		(0.1)		(0.1)
Repayment of promissory notes													(4.7)
Cash paid for financing costs													0
Repurchase of common stock									0		0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0.8		1.1		1.3
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									0		0		0
Cash dividend paid to stockholders									0		0		0
Cash dividend returned to the Company											0
Intercompany loan									(23.2)		(130.5)		189.1
Net cash provided by (used in) financing activities									(22.5)		(129.5)		185.6
Net increase (decrease) in cash and cash equivalents during the period									17.6		(108.3)		223.0
Cash and cash equivalents at beginning of period				157.7				266.0	157.7		266.0					43.0
Cash and cash equivalents at end of period	175.3				157.7				175.3		157.7		266.0			43.0
Non-Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	2.4				6.8				2.4		6.8		2.4			1.8
Short-term investments	0				0				0		0
Receivables:
Trade, less allowance for doubtful receivables	3.2				2.1				3.2		2.1
Intercompany receivables	0.9				0.2				0.9		0.2
Other	5.3				8.1				5.3		8.1
Inventories	7.6				6.4				7.6		6.4
Prepaid expenses and other current assets	0.4				0.4				0.4		0.4
Total current assets	19.8				24.0				19.8		24.0
Investments in and advances to unconsolidated affiliates	0				0				0		0
Property, plant and equipment — net	17.5				15.3				17.5		15.3
Long-term intercompany receivables	15.9				9.5				15.9		9.5
Net asset of VEBAs	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 assets	0.1				0.1				0.1		0.1
Total	53.3				48.9				53.3		48.9
Current liabilities:
Accounts payable	6.3				5.5				6.3		5.5
Intercompany payable	3.3				0.1				3.3		0.1
Accrued salaries, wages and related expenses	3.1				3.4				3.1		3.4
Other accrued liabilities	0.8				1.4				0.8		1.4
Current portion of long-term debt	0								0
Short-term capital leases	0				0				0		0
Total current liabilities	13.5				10.4				13.5		10.4
Net liability of VEBA	0								0
Deferred tax liabilities	0.9				1.2				0.9		1.2
Long-term intercompany payable	0				1.7				0		1.7
Long-term liabilities	8.0				11.2				8.0		11.2
Long-term debt	0				0				0		0
Total liabilities	22.4				24.5				22.4		24.5
Total stockholders’ equity	30.9				24.4				30.9		24.4
Total	53.3				48.9				53.3		48.9
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales									133.9		118.0		124.0
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items									117.8		105.7		110.2
Unrealized losses (gains) on derivative instruments									0		0		0
Depreciation and amortization									1.1		1.1		1.0
Selling, administrative, research and development and general									9.9		8.9		8.2
Non-cash defined benefit net periodic benefit income									0		0		0
Total selling, administrative, research and development and general									9.9		8.9		8.2
Other operating charges, net									0				0
Total costs and expenses									128.8		115.7		119.4
Operating (loss) income									5.1		2.3		4.6
Interest expense									0		0		0
Other (expense) income:
Other income, net									0.4		0		0.6
(Loss) income before income taxes									5.5		2.3		5.2
Income tax provision									0.8		15.7		(2.3)
Earnings in equity of subsidiaries									0		0		0
Net income									6.3		18.0		2.9
Comprehensive (loss) income									6.6		19.0		1.9
Cash flows from operating activities:
Net cash (used in) provided by operating activities									6.7		9.2		5.9
Cash flows from investing activities:
Capital expenditures									(3.0)		(3.9)		(1.5)
Payments to Acquire Available-for-sale Securities									0		0		0
Proceeds from disposal of property, plant and equipment													0
Proceeds from disposition of available for sale securities									0		0
Change in restricted cash											1.0		(0.4)
Net cash used in investing activities									(3.0)		(2.9)		(1.9)
Cash flows from financing activities:
Proceeds from issuance of Senior Notes													0
Repayments of capital lease									0		0		0
Repayment of promissory notes													0
Cash paid for financing costs													0
Repurchase of common stock									0		0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0		0		0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									0		0		0
Cash dividend paid to stockholders									0		0		0
Cash dividend returned to the Company											0
Intercompany loan									(8.1)		(1.9)		(3.4)
Net cash provided by (used in) financing activities									(8.1)		(1.9)		(3.4)
Net increase (decrease) in cash and cash equivalents during the period									(4.4)		4.4		0.6
Cash and cash equivalents at beginning of period				6.8				2.4	6.8		2.4					1.8
Cash and cash equivalents at end of period	2.4				6.8				2.4		6.8		2.4			1.8
Consolidating Adjustments
Current assets:
Cash and cash equivalents	0				0				0		0		0			0
Short-term investments	0				0				0		0
Receivables:
Trade, less allowance for doubtful receivables	0				0				0		0
Intercompany receivables	(209.1)				(0.3)				(209.1)		(0.3)
Other	0				0				0		0
Inventories	(0.9)				(0.6)				(0.9)		(0.6)
Prepaid expenses and other current assets	0				0				0		0
Total current assets	(210.0)				(0.9)				(210.0)		(0.9)
Investments in and advances to unconsolidated affiliates	(1,241.7)				(1,464.4)				(1,241.7)		(1,464.4)
Property, plant and equipment — net	0				0				0		0
Long-term intercompany receivables	(15.9)				(42.4)				(15.9)		(42.4)
Net asset of VEBAs	0				0				0		0
Deferred tax assets — net	7.1				8.9				7.1		8.9
Intangible assets — net	0				0				0		0
Goodwill	0				0				0		0
Other assets	0				0				0		0
Total	(1,460.5)				(1,498.8)				(1,460.5)		(1,498.8)
Current liabilities:
Accounts payable	0				0				0		0
Intercompany payable	(224.6)				(14.0)				(224.6)		(14.0)
Accrued salaries, wages and related expenses	0				0				0		0
Other accrued liabilities	0				0				0		0
Current portion of long-term debt	0								0
Short-term capital leases	0				0				0		0
Total current liabilities	(224.6)				(14.0)				(224.6)		(14.0)
Net liability of VEBA	0								0
Deferred tax liabilities	0				0				0		0
Long-term intercompany payable	(15.9)				(42.4)				(15.9)		(42.4)
Long-term liabilities	0				0				0		0
Long-term debt	0				0				0		0
Total liabilities	(240.5)				(56.4)				(240.5)		(56.4)
Total stockholders’ equity	(1,220.0)				(1,442.4)				(1,220.0)		(1,442.4)
Total	(1,460.5)				(1,498.8)				(1,460.5)		(1,498.8)
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales									(101.2)		(95.7)		(89.9)
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items									(98.6)		(92.8)		(84.0)
Unrealized losses (gains) on derivative instruments									0		0		0
Depreciation and amortization									0		0		0
Selling, administrative, research and development and general									(2.3)		(2.4)		(5.7)
Non-cash defined benefit net periodic benefit income									0		0		0
Total selling, administrative, research and development and general									(2.3)		(2.4)		(5.7)
Other operating charges, net									0				0
Total costs and expenses									(100.9)		(95.2)		(89.7)
Operating (loss) income									(0.3)		(0.5)		(0.2)
Interest expense									0.6		0.4		0.1
Other (expense) income:
Other income, net									(0.6)		(0.3)		(0.1)
(Loss) income before income taxes									(0.3)		(0.4)		(0.2)
Income tax provision									14.1		14.0		11.1
Earnings in equity of subsidiaries									(115.7)		(158.9)		(117.8)
Net income									(101.9)		(145.3)		(106.9)
Comprehensive (loss) income									(26.5)		(150.6)		(165.9)
Cash flows from operating activities:
Net cash (used in) provided by operating activities									0		0		0
Cash flows from investing activities:
Capital expenditures									0		0		0
Payments to Acquire Available-for-sale Securities									0		0		0
Proceeds from disposal of property, plant and equipment													0
Proceeds from disposition of available for sale securities									0		0
Change in restricted cash											0		0
Net cash used in investing activities									0		0		0
Cash flows from financing activities:
Proceeds from issuance of Senior Notes													0
Repayments of capital lease									0		0		0
Repayment of promissory notes													0
Cash paid for financing costs													0
Repurchase of common stock									0		0
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest									0		0		0
Cancellation of shares to cover employees' tax withholdings upon vesting of non-vested shares									0		0		0
Cash dividend paid to stockholders									0		0		0
Cash dividend returned to the Company											0
Intercompany loan									0		0		0
Net cash provided by (used in) financing activities									0		0		0
Net increase (decrease) in cash and cash equivalents during the period									0		0		0
Cash and cash equivalents at beginning of period				0				0	0		0					0
Cash and cash equivalents at end of period	0				0				0		0		0			0
Senior Notes
Cash flows from financing activities:
Principal amount of notes																	225.0
VEBAs [Member]
Cost of products sold:
Non-cash defined benefit net periodic benefit income									$ (23.7)		$ (22.5)		$ (11.9)

[1] See Note 14 for the supplemental disclosure on non-cash transactions.