Cover Page - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 20, 2020	Jun. 28, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-35092
Entity Registrant Name	EXACT SCIENCES CORPORATION
Entity Central Index Key	0001124140
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	441 Charmany Drive
Entity Address, City or Town	Madison
Entity Address, State or Province	WI
Entity Tax Identification Number	02-0478229
Entity Address, Postal Zip Code	53719
City Area Code	608
Local Phone Number	284‑5700
Title of 12(b) Security	Common Stock, $0.01 Par Value
Trading Symbol	EXAS
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Amendment Flag	false
Entity Filer Category	Large Accelerated Filer
Current Fiscal Year End Date	--12-31
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 15,069,783,760
Entity Common Stock, Shares Outstanding		147,967,507
Documents Incorporated by Reference	The registrant intends to file a definitive proxy statement pursuant to Regulation 14A within 120 days after the end of the fiscal year ended December 31, 2019. Portions of such proxy statement are incorporated by reference into Part III of this Form 10‑K.
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY