Balance Sheet Components - Summary of Accrued and Other Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Accrued research and development costs	$ 3,597	$ 4,485
Accrued employee-related costs	1,955	3,223
Accrued professional fees	1,016	357
Operating lease liability	177
Accrued restructuring costs	30	33
Other	289	714
Total accrued and other liabilities	$ 7,064	$ 8,812

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Accrued research and development costs current.

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Carrying value as of the balance sheet date of obligations, excluding pension and other postretirement benefits, incurred through that date and payable for perquisites provided to employees pertaining to services received from them. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Carrying value as of the balance sheet date of obligations incurred through that date and payable for professional fees, such as for legal and accounting services received. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

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Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.

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Carrying amount as of the balance sheet date of known and estimated obligations associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid in the next twelve months or in the normal operating cycle if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

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