PFIZER PROMOTION AGREEMENT (Details) - Cologuard promotion agreement - Pfizer Inc - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2022	Nov. 30, 2021
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contract termination fee			$ 35.9
Service fee based on incremental gross profits over specified baselines and royalties	$ 2.5	$ 7.5
Charges for promotion, sales and marketing	$ 20.6	$ 86.1

Contract Termination Fee

No definition available.

Name:	exas_ContractTerminationFee
Namespace Prefix:	exas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents service fee based on incremental gross profits over specified baselines and royalties.

+ References

No definition available.

+ Details

Name:	exas_ServiceFeeBasedOnIncrementalGrossProfitsOverSpecifiedBaselinesAndRoyalties
Namespace Prefix:	exas_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 808
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479402/808-10-50-1

+ Details

Name:	us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Expenditures for planning and executing the conception, pricing, promotion, and distribution of ideas, goods, and services. Costs of public relations and corporate promotions are typically considered to be marketing costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.4)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

+ Details

Name:	us-gaap_MarketingExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_TypeOfArrangementAxis=us-gaap_ManufacturedProductOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=exas_PfizerIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: