Stock Based Compensation - Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($)
Sharebased Compensation Arrangement By Sharebased Payment Award Options Outstanding Weighted Average Exercise Price And Additional Disclosures [Abstract]
Number of Options, Outstanding, Beginning balance | shares	254,058
Number of Options, Options assumed in the Merger | shares	37,276
Number of Options, Granted | shares	48,544
Number of Options, Exercised | shares	(7,034)
Number of Options, Canceled | shares	(22,775)
Number of Options, Outstanding, Ending balance | shares	310,069
Number of Options, Vested and expected to vest | shares	297,880
Number of Options, Vested and exercisable | shares	66,229
Weighted Average Exercise Price Per Share, Outstanding, Beginning balance | $ / shares	$ 1.94
Weighted Average Exercise Price Per Share, Options assumed in the Merger | $ / shares	177.57
Weighted Average Exercise Price Per Share, Granted | $ / shares	17.25
Weighted Average Exercise Price Per Share, Exercised | $ / shares	5.93
Weighted Average Exercise Price Per Share, Canceled | $ / shares	217.32
Weighted Average Exercise Price Per Share, Outstanding, Ending balance | $ / shares	9.55
Weighted Average Exercise Price Per Share, Vested and expected to vest | $ / shares	9.76
Weighted Average Exercise Price Per Share, Vested and exercisable | $ / shares	$ 29.09
Weighted Average Remaining Contractual Life, Ending balance	9 years
Weighted Average Remaining Contractual Life, Vested and expected to vest	8 years 11 months 27 days
Weighted Average Remaining Contractual Life, Vested and exercisable	8 years 3 months
Aggregate Intrinsic Value, Beginning balance | $	$ 4,574	$ 3,369
Aggregate Intrinsic Value, Vested and expected to vest | $	4,384
Aggregate Intrinsic Value, Vested and exercisable | $	$ 775