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Description of contract with a patient.

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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The increase (decrease) during the reporting period in amount due within one year (or one business cycle) from customers for the credit sale of goods and services.

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The increase (decrease) during the reporting period, excluding the portion taken into income, in the liability reflecting revenue yet to be earned for which cash or other forms of consideration was received or recorded as a receivable.

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The increase (decrease) during the reporting period in other obligations or expenses incurred but not yet paid.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented.

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Organization and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Organization and Basis of Presentation [Line Items]
Increase (decrease) in trade receivables	$ (2,255)	$ 9,112	$ 3,016	$ 16,661	$ 23,228
Increase (decrease) in net revenue	64,756	50,109	178,395	123,365	177,026
Increase (decrease) in net loss	$ (11,694)	$ (11,498)	$ (47,928)	$ (50,717)	$ (61,662)
Increase (decrease) in basic and diluted net loss per ordinary share	$ (0.13)	$ (0.13)	$ (0.52)	$ (0.57)	$ (0.70)
Increase in other payables and accrued expenses	$ 3,220	$ 4,830	$ (5,608)	$ 8,308	$ 14,460
Accounting Standards Update 2014-09 [Member]
Organization and Basis of Presentation [Line Items]
Increase (decrease) in trade receivables			(2,223)		2,807
Increase in deferred revenue					645
Cumulative deficit effect adjustment resulting from ASU 2014-09 adoption	(2,381)		(2,381)		$ (2,162)
Increase (decrease) in net loss	$ (827)		$ 4,543
Increase (decrease) in basic and diluted net loss per ordinary share	$ 0.01		$ (0.05)
Increase in other payables and accrued expenses			$ 960
Accounting Standards Update 2014-09 [Member] \| Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Organization and Basis of Presentation [Line Items]
Increase (decrease) in net revenue	$ 901		$ (4,629)
Accounting Standards Update 2014-09 [Member] \| First Generation Optune System Field Equipment [Member]
Organization and Basis of Presentation [Line Items]
Identify the contract with patient			Identify the contract with a patient. A contract with a patient exists when (i) the Company enters into an enforceable contract with a patient that defines each party’s rights regarding delivery of and payment for Optune, (ii) the contract has commercial substance and (iii) the Company determines that collection of substantially all consideration for Optune is probable based on the payer’s intent and ability to pay the promised consideration. The evidence of a contract generally consists of a prescription, a patient service agreement and the verification of the assigned payer for the contract and intention to collect.
Identify the performance obligations in the contract, description			Optune contracts include the lease of the device, the supply obligation of disposable transducer arrays and technical support for the term of treatment. To the extent a contract includes multiple promised products and/or services, the Company must apply judgment to determine whether those products and/or services are capable of being distinct in the context of the contract. If these criteria are not met the promised products and/or services are accounted for as a combined performance obligation. In the Company’s case, Optune’s device, support, and disposables are provided as one inseparable package of monthly treatment for a single monthly fee
Determine the transaction price, description			The transaction price is determined based on the consideration to which the Company will be entitled in exchange for providing Optune to the patient.
Allocate the transaction price to performance obligations in the contract, description			If a contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. As discussed above, there is one performance obligation under the Company’s contracts and, therefore, the monthly transaction price determined for the performance obligation will be recognized over time ratably over the monthly term of the treatment.
Recognize revenue when or as the company satisfies a performance obligation, description			The Company satisfies performance obligations over time as discussed above. Revenue is recognized at the time the related performance obligation is satisfied by transferring a promised service to a patient. The patient consumes the benefits of Optune treatment on a daily basis over the monthly term. As this criterion is met, the revenues will be recognized over the monthly term.