Summary of Information Regarding Option Activity (Detail) (USD $)	9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013
Options Outstanding
Options outstanding at January 1, 2014	1,610,988		1,670,688
Granted	376,698
Exercised	(622,538)
Forfeited/Cancelled	(105,831)
Options outstanding at September 30, 2014	1,259,317		1,670,688
Options exercisable at September 30, 2014	480,300
Vested and expected to vest at September 30, 2014	1,169,331	[1]
Weighted-Average Exercise Price Per Share
Options outstanding at January 1, 2014	$ 5.07		$ 4.87
Granted	$ 13.10
Exercised	$ 4.41
Forfeited/Cancelled	$ 7.49
Options outstanding at September 30, 2014	$ 7.61		$ 4.87
Options exercisable at September 30, 2014	$ 4.17
Vested and expected to vest at September 30, 2014	$ 7.43	[1]
Weighted-Average Remaining Contractual Term (in years)
Options outstanding at September 30, 2014	7 years 3 months 4 days
Options exercisable at September 30, 2014	4 years 9 months 18 days
Vested and expected to vest at September 30, 2014	7 years 1 month 28 days	[1]
Aggregate Intrinsic Value
Options outstanding at September 30, 2014	$ 15,596,097
Options exercisable at September 30, 2014	7,559,847
Vested and expected to vest at September 30, 2014	$ 14,681,625	[1]

[1] This represents the number of vested options as of September 30, 2014 plus the number of unvested options expected to vest as of September 30, 2014 based on the unvested outstanding options at September 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.