Acquisition, Alexco Pro Forma Table (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Net sales (combined)	$ 314.0	$ 335.5	$ 345.2	$ 365.4	$ 317.6	$ 322.3	$ 338.8	$ 322.6	$ 1,360.1		$ 1,301.3		$ 1,079.1
Net income (combined)	9.1	29.2	21.0	26.5	6.1	4.1	4.1	10.8	85.8		25.1		12.0
Basic earnings per share (combined)	$ 0.48	$ 1.52	$ 1.10	$ 1.39	$ 0.33	$ 0.21	$ 0.22	$ 0.57	$ 4.49		$ 1.32		$ 0.61
Diluted earnings per share (combined)	$ 0.47	$ 1.51	$ 1.09	$ 1.38	$ 0.33	$ 0.21	$ 0.22	$ 0.57	$ 4.45	[1],[2]	$ 1.32	[1],[2]	$ 0.61	[1],[2]
Alexco
Business Acquisition, Pro Forma Information
Net sales (combined)													1,110.7
Net income (combined)													16.9
Basic earnings per share (combined)													$ 0.87
Diluted earnings per share (combined)													$ 0.87
Net sales									44.5		42.8
Net income before income taxes									$ 9.0		$ 10.5

[1] Diluted weighted-average number of common shares outstanding and diluted earnings per share for 2012 is based on the treasury method. Diluted weighted-average number of common shares outstanding and diluted earnings per share for 2011 and 2010 are based on the two-class method (see Note 1 and Note 14).

[2] The diluted weighted-average number of common shares outstanding and diluted earnings per share for 2012 were calculated using the treasury method. The diluted weighted-average number of common shares outstanding and diluted earnings per share for 2011 and 2010 were calculated using the two-class method (see Note 1).