The amount of a currency that the reporting entity is obligated to sell at settlement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
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- Definition

Research and development grants.

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- Definition

Average contractual rate at which a foreign currency can be purchased or sold.

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- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
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-Paragraph 1A
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The amount of compensation earned (contract income) under a research and development arrangement accounted for as a contract to perform research and development for others.

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-Publisher FASB
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Commitments and Contingencies - Additional Information (Detail) £ in Thousands, $ in Thousands	9 Months Ended	12 Months Ended
	Dec. 31, 2018 GBP (£)	Dec. 31, 2008 GBP (£)	Dec. 31, 2018 USD ($) Contracts $ / £
Commitments And Contingencies [Line Items]
Research and development grant funding from Scottish Enterprise \| £		£ 1,791
Claims from grant \| £	£ 1,790
January 2019 through March 2019 [Member]
Commitments And Contingencies [Line Items]
Number of forward exchange contracts \| Contracts			3
Forward exchange contracts sold \| $			$ 500
Forward exchange contracts exchange rate pounds sterling to US dollar \| $ / £			1.4140
July 2019 through September 2019 [Member]
Commitments And Contingencies [Line Items]
Number of forward exchange contracts \| Contracts			3
Forward exchange contracts sold \| $			$ 500
Forward exchange contracts exchange rate pounds sterling to US dollar \| $ / £			1.30
April 2019 through June 2019 [Member]
Commitments And Contingencies [Line Items]
Number of forward exchange contracts \| Contracts			3
Forward exchange contracts sold \| $			$ 500
Forward exchange contracts exchange rate pounds sterling to US dollar \| $ / £			1.3520