Summary of Information Regarding Option Activity (Detail) (USD $)	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Options Outstanding
Options outstanding at January 1, 2014	1,610,988		1,795,588
Granted	339,698
Exercised	(573,238)
Forfeited/Cancelled	(64,707)
Options outstanding at June 30, 2014	1,312,741		1,795,588
Options exercisable at June 30, 2014	419,600
Vested and expected to vest at June 30, 2014	1,211,138	[1]
Weighted-Average Exercise Price Per Share
Options outstanding at January 1, 2014	$ 5.07		$ 4.53
Granted	$ 12.37
Exercised	$ 4.36
Forfeited/Cancelled	$ 6.92
Options outstanding at June 30, 2014	$ 7.19		$ 4.53
Options exercisable at June 30, 2014	$ 4.05
Vested and expected to vest at June 30, 2014	$ 7.09	[1]
Weighted-Average Remaining Contractual Term (in years)
Options outstanding at June 30, 2014	7 years 7 months 17 days
Options exercisable at June 30, 2014	5 years 1 month 10 days
Vested and expected to vest at June 30, 2014	7 years 6 months 22 days	[1]
Aggregate Intrinsic Value
Options outstanding at June 30, 2014	$ 20,475,525
Options exercisable at June 30, 2014	7,862,172
Vested and expected to vest at June 30, 2014	$ 19,013,813	[1]

[1] This represents the number of vested options as of June 30, 2014 plus the number of unvested options expected to vest as of June 30, 2014 based on the unvested outstanding options at June 30, 2014 adjusted for estimated forfeiture rates of 8% for awards granted to non-executive level employees and 3% for awards granted to executive level employees.