Stockholders' Equity (Detail) - Activity Under Equity Award Plans And Related Information (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant	3,023	2,436
Number of shares	5,710	4,672
Weighted-average exercise price (in dollars per share)	$ 8.85	$ 9.79
Shares authorized	1,000
Options granted	(100)
Options granted	100
Options granted (in dollars per share)	$ 13.26
Options exercised	(823)
Options exercised (in dollars per share)	$ 3.39
Options forfeited	315
Options forfeited	(315)
Options forfeited (in dollars per share)	$ 10.50
Restricted stock units granted	(2,037)
Restricted stock units forfeited	235
Weighted-average remaining contractual life in years	7 years 6 months
Aggregate instrinsic value (in dollars)	$ 35,879
Vested and exercisable [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested and exercisable (shares)	1,970
Vested and exercisable (in dollars per share)	$ 10.06
Vested and exercisable (weighted-average contractual life)	7 years 2 months
Vested and exercisable (intrinsic value)	15,377
Vested and expected to vest [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested and expected to vest (shares)	4,359
Vested and expected to vest (in dollars per share)	$ 9.80
Vested and expected to vest (weighted-average contractual life)	7 years 6 months
Vested and expected to vest (intrinsic value)	$ 33,597