Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Income Taxes [Line Items]
Effective tax rate	4.40%	58.30%	22.40%	98.50%
Effective tax rate reconciliation, release of liability due to the expiration of a contractual obligation	$ 3.1		$ 3.1
Effective tax rate reconciliation, favorable adjustment to uncertain tax positions			3.9
Effective tax rate reconciliation, reversal of related deferred tax assets	1.7		1.7
Earnings of foreign entities	(0.2)		10.2
Unrecognized tax benefits for uncertain tax positions	3.9		3.9		8.4
Unrecognized tax benefits for uncertain tax positions, liabilities for interest and penalties	2.2		2.2		2.2
Reasonably possible decrease in unrecognized tax benefits within the next 12 months	$ 2.7		$ 2.7