Business combinations - Schedule of consideration paid (Details) $ in Thousands	Dec. 23, 2017 USD ($) shares
Business Acquisition [Line Items]
Total consideration	$ 14,839
Discuva Limited
Business Acquisition [Line Items]
Cash	$ 8,149
Number of shares issued (in shares) \| shares	586,854
586,854 new Summit Therapeutics Shares issued	$ 6,690

Number of shares of equity interests issued or issuable to acquire entity.

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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.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount of equity interests of the acquirer, including instruments or interests issued or issuable in consideration for the business combination.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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