Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Receivables:
Allowance for doubtful receivables	$ 0.8	$ 0.8
Deferred tax liability relating to VEBAs	$ 152.4	$ 136.9
Stockholders' equity:
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	90,000,000	90,000,000
Common Stock, Shares, Issued	21,103,700	21,037,841
Common Stock, Shares, Outstanding	18,147,017	19,313,235
Common stock owned by Union VEBA, shares	0	0
Treasury stock, shares	2,956,683	1,724,606