Subsequent Event - Additional Information (Detail) $ in Millions	1 Months Ended	3 Months Ended
Jan. 31, 2018 Employee	Mar. 31, 2018 USD ($)
Scenario, Forecast [Member]
Subsequent Event [Line Items]
Employee termination benefits		$ 1.1
Intangible asset impairment charges		$ 0.3
Subsequent Event [Member]
Subsequent Event [Line Items]
Number of staff reduced \| Employee	40

Amount of increase in benefit obligation for benefits provided to employees payable from defined benefit plan or payable upon retirement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(10)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

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

+ References

No definition available.

+ Details

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- Definition

Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan and expenses resulting from the write-down of assets. Excludes expenses related to a business combination, a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

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- Details

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