Commitments And Contingencies (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended		3 Months Ended	12 Months Ended
	Dec. 31, 2010	Mar. 31, 2010	Mar. 31, 2013 ATP [Member]	Dec. 31, 2012 ATP [Member]
Commitments And Contingencies [Line Items]
Tax assessment settled with payments	$ 3.9	$ 12.2
Amount of interest, penalties and monetary restatement fees on tax assessments	7.8
Value of Brazilian subsidiary served with assessments	13.0
Receivables from bankruptcy			1.4	1.4
Customer prepayments			4.3	4.3
Provision for loss due to bankruptcy			$ 0	$ 0