Income Taxes - Significant Components of Company's Deferred Tax Assets and Deferred Tax Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets:
Deferred rent		$ 9
Accrued compensation	$ 618	16
Accrued liabilities	700	83
Tax loss carryforwards	37,857	17,692
Intangible assets	361	351
Share-based compensation	412	304
Tax credits	3,930	2,237
Facility financing lease obligation	2,881
Other	120	53
Total deferred tax assets	46,879	20,745
Less valuation allowance	(43,800)	(20,711)
Net deferred tax asset	3,079	34
Deferred tax liabilities:
Fixed assets	$ (3,079)	$ (34)