Name:	exas_BusinessAcquisitionEquityInterestIssuedOrIssuableMeasurementPriceBottomOfRange
Namespace Prefix:	exas_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

Represents the maximum measurement price pertaining to the business acquisition equity interest issued or issuable.

No definition available.

Name:	exas_BusinessAcquisitionEquityInterestIssuedOrIssuableMeasurementPriceMaximum
Namespace Prefix:	exas_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

Represents the minimum measurement price pertaining to the business acquisition equity interest issued or issuable.

No definition available.

Name:	exas_BusinessAcquisitionEquityInterestIssuedOrIssuableMeasurementPriceMinimum
Namespace Prefix:	exas_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

Represents the top of the threshold for the measurement price pertaining to the business acquisition equity interest issued or issuable.

No definition available.

Name:	exas_BusinessAcquisitionEquityInterestIssuedOrIssuableMeasurementPriceTopOfRange
Namespace Prefix:	exas_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

Conversion ratio for common shares to be issued as consideration for each common share outstanding of the acquiree.

No definition available.

Name:	exas_BusinessAcquisitionEquityInterestIssuedOrIssuableNumberOfSharesIssuedExchangeRatio
Namespace Prefix:	exas_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Represents a second conversion ratio for common shares to be issued as consideration for each common share outstanding of the acquiree.

No definition available.

Name:	exas_BusinessAcquisitionEquityInterestIssuedOrIssuableNumberOfSharesIssuedExchangeRatioTwo
Namespace Prefix:	exas_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Represents the price used to determine the measurement price.

No definition available.

Name:	exas_BusinessAcquisitionPriceUsedToCalculateMeasurementPrice
Namespace Prefix:	exas_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

Represents the conversion share price to be received by the acquired entity shareholders.

No definition available.

Name:	exas_BusinessAcquisitionSharesConvertedSharePrice
Namespace Prefix:	exas_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

Represent the volume-weighted average price, number of trading days.

No definition available.

Name:	exas_CollarPercentageVolumeWeightedAveragePriceNumberOfTradingDays
Namespace Prefix:	exas_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Name:	us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

No definition available.