Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 18, 2019
Document Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Trading Symbol	NVCR
Entity Registrant Name	Novocure Ltd
Entity Central Index Key	0001645113
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		98,176,183
Entity File Number	001-37565
Entity Tax Identification Number	981057807
Entity Address, Address Line One	No. 4 The Forum
Entity Address, Address Line Two	Grenville Street
Entity Address, City or Town	St. Helier
Entity Address, State or Province	Jersey
Entity Address, Postal Zip Code	JE2 4UF
City Area Code	44 (0) 15
Local Phone Number	3475 6700