Name:	ntra_ContractWithCustomerLiabilityAdditions
Namespace Prefix:	ntra_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration from customer has been received or is due, from sale of business unit.

No definition available.

Name:	ntra_ContractwithcustomerliabilityincreaseDecreaseForContractTransferredInSaleOfBusinessUnit
Namespace Prefix:	ntra_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130532-203044

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

Name:	us-gaap_ContractWithCustomerLiability
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of revenue recognized arising from contract liability from change in timeframe for performance obligation to be satisfied.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130551-203045

Name:	us-gaap_ContractWithCustomerLiabilityChangeInTimeframePerformanceObligationSatisfiedRevenueRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of increase (decrease) in revenue recognized for cumulative catch-up adjustment from change in measure of progress which (increases) decreases obligation to transfer good or service to customer for which consideration from customer has been received or is due.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130551-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- References

No definition available.