Guarantor and Non-Guarantor Financial Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				3 Months Ended				3 Months Ended				3 Months Ended				3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012		Dec. 31, 2012	Mar. 31, 2013 Parent	Mar. 31, 2012 Parent		Dec. 31, 2012 Parent	Mar. 31, 2013 Guarantor Subsidiaries	Mar. 31, 2012 Guarantor Subsidiaries		Dec. 31, 2012 Guarantor Subsidiaries	Mar. 31, 2013 Non-Guarantor Subsidiaries	Mar. 31, 2012 Non-Guarantor Subsidiaries		Dec. 31, 2012 Non-Guarantor Subsidiaries	Mar. 31, 2013 Consolidating Adjustments	Mar. 31, 2012 Consolidating Adjustments		Dec. 31, 2012 Consolidating Adjustments	May 23, 2012 Senior Notes
Condensed Financial Statements [Line Items]
Principal amount of notes	$ 225.0			$ 225.0																	$ 225.0
Ownership interest by parent	100.00%
Current assets:
Cash and cash equivalents	248.0	77.3			5.0	5.0			241.6	71.6			1.4	0.7			0	0
Short-term investments	85.6			85.0	0			0	85.6			85.0	0			0	0			0
Receivables:
Trade, less allowance for doubtful receivables	141.8			123.8	0			0	137.8			121.5	4.0			2.3	0			0
Intercompany receivables	0			0	0			0	0.2			(10.3)	0.3			0.4	(0.5)			9.9
Other	11.8			3.4	0			0	1.6			1.3	10.2			2.1	0			0
Inventories	199.3			186.0	0			0	193.0			178.7	6.6			7.3	(0.3)			0
Prepaid expenses and other current assets	71.0			70.1	0			0	68.9			68.1	2.1			2.0	0			0
Total current assets	757.5			741.7	5.0			5.0	728.7			710.3	24.6			16.5	(0.8)			9.9
Investments in and advances to unconsolidated affiliates	0			0	1,331.5			1,284.1	15.8			7.4	0			0	(1,347.3)			(1,291.5)
Property, plant, and equipment – net	386.4			384.3	0			0	373.9			371.8	12.5			12.5	0			0
Long-term intercompany receivables	0			0	140.4			163.7	0.9			0.4	8.9			6.4	(150.2)			(170.5)
Net asset in respect of VEBA	372.5			365.9	0			0	372.5			365.9	0			0	0			0
Deferred tax assets — net	87.0			102.0	0			0	78.7			93.4	(1.0)			(0.8)	9.3			9.4
Intangible assets – net	35.0			35.4	0			0	35.0			35.4	0			0	0			0
Goodwill	37.2			37.2	0			0	37.2			37.2	0			0	0			0
Other assets	88.8			86.0	69.5			64.0	19.2			19.2	0.1			3.0	0			(0.2)
Total	1,764.4			1,752.5	1,546.4			1,516.8	1,661.9			1,641.0	45.1			37.6	(1,489.0)			(1,442.9)
Current liabilities:
Accounts payable	73.2			62.5	1.5			0.1	64.7			56.5	7.0			5.9	0			0
Intercompany payable	0			0	0			0	3.2			0.3	0.2			0.2	(3.4)			(0.5)
Accrued salaries, wages, and related expenses	33.1			39.3	0			0	30.3			36.7	2.8			2.6	0			0
Other accrued liabilities	38.4			51.8	10.1			3.5	27.0			47.8	1.3			0.5	0			0
Payable to affiliate	12.3			7.9	0			0	12.3			7.9	0			0	0			0
Short-term capital lease	0.2			0.1	0			0	0.2			0.1	0			0	0			0
Total current liabilities	157.2			161.6	11.6			3.6	137.7			149.3	11.3			9.2	(3.4)			(0.5)
Net liability in respect of VEBA	4.9			5.3	0			0	4.9			5.3	0			0	0			0
Long-term intercompany payable	0			0	0			0	149.3			170.0	0.9			0.5	(150.2)			(170.5)
Long-term liabilities	135.2			134.5	67.7			62.1	48.0			49.6	19.5			22.8	0			0
Long-term debt	382.3			380.3	382.3			380.3	0			0	0			0	0			0
Total liabilities	679.6			681.7	461.6			446.0	339.9			374.2	31.7			32.5	(153.6)			(171.0)
Total stockholders’ equity	1,084.8			1,070.8	1,084.8			1,070.8	1,322.0			1,266.8	13.4			5.1	(1,335.4)			(1,271.9)
Total	1,764.4			1,752.5	1,546.4			1,516.8	1,661.9			1,641.0	45.1			37.6	(1,489.0)			(1,442.9)
CONDENSED CONSOLIDATING STATEMENT OF COMPREHENSIVE INCOME
Net sales	337.4	365.4			0	0			331.8	355.5			30.4	32.6			(24.8)	(22.7)
Cost of products sold:
Cost of products sold, excluding depreciation and amortization and other items	263.6	298.1			0	0			259.7	290.5			27.0	29.9			(23.1)	(22.3)
Unrealized losses (gains) on derivative instruments	0.7	(3.1)			0	0			0.7	(3.1)			0	0			0	0
Depreciation and amortization	7.0	6.3			0	0			6.7	6.1			0.3	0.2			0	0
Selling, administrative, research and development, and general	16.1	17.9			0.4	0.5			14.8	17.7			2.4	0			(1.5)	(0.3)
Total costs and expenses	287.4	319.2			0.4	0.5			281.9	311.2			29.7	30.1			(24.6)	(22.6)
Operating (loss) income	50.0	46.2			(0.4)	(0.5)			49.9	44.3			0.7	2.5			(0.2)	(0.1)
Other (expense) income:
Interest expense	(9.3)	(4.1)			(9.1)	(4.0)			(0.3)	(0.1)			0	0			0.1	0
Other income, net	1.0	0.7			0.4	0.5			0.6	0.2			0.1	0			(0.1)	0
(Loss) income before income taxes	41.7	42.8			(9.1)	(4.0)			50.2	44.4			0.8	2.5			(0.2)	(0.1)
Income tax (provision) benefit	(8.2)	(16.3)			0	0			(19.0)	(16.8)			7.2	(0.7)			3.6	1.2
Earnings in equity of subsidiaries	0	0			42.6	30.5			7.8	1.7			0	0			(50.4)	(32.2)
Net income	33.5	26.5			33.5	26.5			39.0	29.3			8.0	1.8			(47.0)	(31.1)
Comprehensive income	34.7	27.6			34.7	27.6			39.8	30.7			8.4	1.5			(48.2)	(32.2)
Cash flows from operating activities:
Net cash (used in) provided by operating activities	6.3	35.0	[1]		(0.5)	0.1	[1]		5.4	36.0	[1]		1.4	(1.1)	[1]		0	0	[1]
Cash flows from investing activities:
Capital expenditures	(9.3)	(9.0)			0	0			(9.0)	(8.7)			(0.3)	(0.3)			0	0
Purchase of available for sale securities	(85.6)	0			0				(85.6)				0				0
Proceeds from sale of available for sale securities	85.2	0			0				85.2				0				0
Change in restricted cash	0	7.2				6.9				0.3				0				0
Net cash used in investing activities	(9.7)	(1.8)			0	6.9			(9.4)	(8.4)			(0.3)	(0.3)			0	0
Cash flows from financing activities:
Excess tax benefit upon vesting of non-vested shares and dividend payment on unvested shares expected to vest	0.8	1.3			0	0			0.8	1.3			0	0			0	0
Cancellation of shares to cover employees’ tax withholdings upon vesting of non-vested shares	(2.2)	(2.1)			(2.2)	(2.1)			0	0			0	0			0	0
Cash dividend paid to stockholders	(5.9)	(4.9)			(5.9)	(4.9)			0	0			0	0			0	0
Repurchase of common stock	(14.7)	0			(14.7)				0				0				0
Intercompany loan	0	0			23.3	0			(21.2)	(0.3)			(2.1)	0.3			0	0
Net cash provided by (used in) financing activities	(22.0)	(5.7)			0.5	(7.0)			(20.4)	1.0			(2.1)	0.3			0	0
Net (decrease) increase in cash and cash equivalents during the period	(25.4)	27.5			0	0			(24.4)	28.6			(1.0)	(1.1)			0	0
Cash and cash equivalents at beginning of period	273.4	49.8			5.0	5.0			266.0	43.0			2.4	1.8			0	0
Cash and cash equivalents at end of period	$ 248.0	$ 77.3			$ 5.0	$ 5.0			$ 241.6	$ 71.6			$ 1.4	$ 0.7			$ 0	$ 0

[1] The Company treats changes in long-term intercompany balances that relate to financing activities as cash flow from financing activities. In the above table, the Company has revised the previous classification of the changes in such intercompany balances during the quarter ended March 31, 2012 from cash flows from operating activities to a separate line item in cash flows from financing activities captioned "intercompany loan”.