Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 29, 2019
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2019
Entity File Number	001-35092
Entity Registrant Name	EXACT SCIENCES CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	02-0478229
Entity Address, Address Line One	441 Charmany Drive
Entity Address, City or Town	Madison
Entity Address, State or Province	WI
Entity Address, Postal Zip Code	53719
City Area Code	608
Local Phone Number	535-8815
Title of 12(b) Security	Common Stock
Trading Symbol	EXAS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current 1	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001124140
Amendment Flag	false
Entity Common Stock, Shares Outstanding		129,485,303