Goodwill and Other Identifiable Intangible Assets - Changes in Carrying Amount of Goodwill (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Acquired Finite-Lived Intangible Assets [Line Items]
Balance beginning	$ 72.1	$ 72.1
Acquisitions	2.6	0.4
Currency translation	0.9	(0.4)
Balance ending	75.6	72.1
Carbon Materials & Chemicals [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Balance beginning	69.4	69.6
Acquisitions	0	0.1
Currency translation	0.8	(0.3)
Balance ending	70.2	69.4
Railroad & Utility Products [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Balance beginning	2.7	2.5
Acquisitions	2.6	0.3
Currency translation	0.1	(0.1)
Balance ending	$ 5.4	$ 2.7