Summary of Significant Accounting Policies - Computation of Basic and Diluted Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net loss, basic and diluted	$ (57,002)	$ (42,463)
Denominator:
Weighted average common shares outstanding	52,520	35,402
Weighted average unvested common shares subject to repurchase	(286)	(87)
Weighted average common shares outstanding - basic and diluted	52,234	35,315
Net loss per share, basic and diluted	$ (1.09)	$ (1.20)

The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=117326831&loc=d3e1337-109256

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- Definition

Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
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Average number of shares or units issued and outstanding that are used in calculating basic and diluted earnings per share (EPS).

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Number of shares of common stock subject to repurchase or cancellation determined by relating the portion of time within a reporting period that these shares have been outstanding to the total time in that period. Common stock subject to repurchase are outstanding common shares that are contingently returnable (that is, subject to recall).

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- Definition

This element represents the weighted average total number of shares issued throughout the period including the first (beginning balance outstanding) and last (ending balance outstanding) day of the period before considering any reductions (for instance, shares held in treasury) to arrive at the weighted average number of shares outstanding. Weighted average relates to the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Such concept is used in determining the weighted average number of shares outstanding for purposes of calculating earnings per share (basic).

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