Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Significant Accounting Policies [Line Items]
Net loss	$ (7,151)	$ 1,753
Accumulated deficit	345,679		$ 338,528
Cash, cash equivalents and available-for-sale investments	$ 50,600
Shares used in computing diluted net income (loss) per share	14,103,783	6,884,797
Restricted Stock Units [Member]
Significant Accounting Policies [Line Items]
Shares used in computing diluted net income (loss) per share		3,006
Pangu BioPharma [Member] | Hong Kong [Member]
Significant Accounting Policies [Line Items]
Majority-owned subsidiary percentage	98.00%