v3.6.0.2

Subsequent Events (Details) - Subsequent Event | 1 Months Ended
--- | ---
Jan. 31, 2017 USD ($)
Subsequent Event [Line Items] |
Amended agreement, number of vendors | $ 1
Minimum purchase commitment amount for 2017 | 3,600,000
Minimum purchase commitment amount for 2018 | $ 4,500,000

X
- Definition Represents the number of vendors with which the entity has amended an existing agreement. + References No definition available. + Details
Name: | ntra_AmendedAgreementNumberOfVendors
Namespace Prefix: | ntra_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Minimum amount of purchase arrangement maturing in the next fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments. + References No definition available. + Details
Name: | us-gaap_PurchaseObligationDueInNextTwelveMonths
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Minimum amount of purchase arrangement maturing in the second fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments. + References No definition available. + Details
Name: | us-gaap_PurchaseObligationDueInSecondYear
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition 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. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |