Summary of Changes in Stock Options Outstanding (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding at December 31, 2011, Number of shares	64,245
Assumed in SandForce acquisition, Number of shares	7,542
Granted, Number of shares	5,389
Exercised, Number of shares	(14,385)
Canceled, Number of shares	(4,758)
Options outstanding at September 30, 2012, Number of shares	58,033
Options exercisable at September 30, 2012, Number of shares	35,670
Options outstanding at December 31, 2011, Weighted-Average Exercise Price Per Share	$ 6.19
Assumed in SandForce acquisition, Weighted-Average Exercise Price Per Share	$ 0.75
Granted, Weighted-Average Exercise Price Per Share	$ 8.40
Exercised, Weighted-Average Exercise Price Per Share	$ 5.32
Canceled, Weighted-Average Exercise Price Per Share	$ 8.69
Options outstanding at September 30, 2012, Weighted-Average Exercise Price Per Share	$ 5.70
Options exercisable at September 30, 2012, Weighted-Average Exercise Price Per Share	$ 6.13
Options outstanding at September 30, 2012,Weighted-Average Remaining Contractual Term	3 years 10 months 28 days
Options exercisable at September 30, 2012,Weighted-Average Remaining Contractual Term	2 years 8 months 16 days
Options outstanding at September 30, 2012, Aggregate Intrinsic Value	$ 102,654
Options exercisable at September 30, 2012, Aggregate Intrinsic Value	$ 52,025