Date the restructuring activities were initiated or are expected to be initiated, in CCYY-MM-DD format.

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-Topic 420
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- Definition

The number of positions eliminated during the period as a result of restructuring activities.

+ References

No definition available.

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- Definition

The number of positions eliminated during the period as a percentage of total positions eliminated during the period in connection with the restructuring plan(s).

+ References

No definition available.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 1
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-Section S99
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-Subparagraph (SAB Topic 5.P.4(b))
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-Name Accounting Standards Codification
-Topic 420
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- Definition

Restructuring plan notification date to affected employees.

+ References

No definition available.

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Restructuring Plan - Additional Information (Detail) - Restructuring Plan [Member] $ in Millions		1 Months Ended	6 Months Ended
	Jun. 26, 2018 Employee	Oct. 31, 2017	Jun. 30, 2018 USD ($)
Restructuring Cost And Reserve [Line Items]
Restructuring plan effective date		Oct. 20, 2017
Total number of employees reduced \| Employee	14
Approximate reduction as a percent of workforce	59.00%
Restructuring plan notification date to affected employees	Jun. 26, 2018
One-time severance-related charge			$ 3.5
General and administrative [Member]
Restructuring Cost And Reserve [Line Items]
One-time severance-related charge			1.2
Research and development [Member]
Restructuring Cost And Reserve [Line Items]
One-time severance-related charge			$ 2.3