Income Taxes - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended		3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Realized Tax Savings	Sep. 30, 2013 Realized Tax Savings	Dec. 31, 2008 China Subsidiary Prior Tax Rate	Dec. 31, 2008 China Subsidiary Revised Tax Rate
Income Tax Contingency [Line Items]
Effective tax rate	0.02%			15.00%	15.20%	(8.90%)			25.00%	15.00%
U.S federal statutory rate	35.00%				35.00%
Reinstatement of the federal research and development tax credit			$ 2.2
Non-deductible acquisition related expenses		1.0
Windfall tax benefits realized on disqualifying disposition of stock	0.5				1.5
Discrete benefits from reserve releases for statute expirations	2.0			3.2		3.6
Unrecognized tax benefits	22.6				22.6
Anticipated reduction in uncertain tax positions	1.5				1.5
Accrued interest and penalties related to uncertain tax positions	1.6			1.6	1.6	1.6
Tax benefits realized							$ 1.0	$ 1.0
Tax benefits per share							$ 0.01	$ 0.01