Reconciliation of Beginning and Ending Amounts of Gross Uncertain Tax Positions (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of Unrecognized Tax Benefits [Line Items]
Balance, beginning of the period	$ 21.5	$ 18.5	$ 15.1
Additions for current year tax positions	6.1	3.1	3.5
Additions for tax positions of prior years			1.6
Currency fluctuations	(0.1)	(0.1)	0.3
Reduction for tax positions of prior years			(2.0)
Settlements with taxing authorities	(5.8)
Balance, end of the period	$ 21.7	$ 21.5	$ 18.5