COMMITMENTS AND CONTINGENCIES - Capital Lease (Details)	12 Months Ended
Dec. 31, 2012 USD ($)
COMMITMENTS AND CONTINGENCIES
Laboratory equipment	$ 1,200,000
Lease term of leased equipment	3 years
Rental payment per month	$ 32,000

Represents the amount of rental payment, which the entity is required to make per month under capital leases over the term of lease agreement.

No definition available.

Name:	exas_CapitalLeasesRentalPaymentsPerMonth
Namespace Prefix:	exas_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration