Name:	ntra_AccruedChargesForOutsourcedTesting
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Carrying value as of the balance sheet date of obligations incurred through that date and payable for clinical trials and studies.

No definition available.

Name:	ntra_AccruedClinicalTrialsAndStudies
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Carrying value as of the balance sheet date of obligations incurred and payable for fixed assets.

No definition available.

Name:	ntra_AccruedFixedAssetPurchases
Namespace Prefix:	ntra_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying value as of the balance sheet date of accrued interest.

No definition available.

Name:	ntra_AccruedInterest
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying value as of the balance sheet date of obligations incurred through that date and payable for shipping charges.

No definition available.

Name:	ntra_AccruedShippingCharges
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying value as of the balance sheet date of obligations incurred through that date and payable for specimen service fees.

No definition available.

Name:	ntra_AccruedSpecimenServiceFees
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Carrying value as of the balance sheet date of obligations incurred through that date and payable for testing and laboratory materials from suppliers.

No definition available.

Name:	ntra_AccruedTestingAndLaboratoryMaterialsFromSuppliers
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Represents deposits held for sublease.

No definition available.

Name:	ntra_DepositsHeldForSublease
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Data Type:	xbrli:monetaryItemType
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Amount of expenses not otherwise itemized or categorized in the footnotes to the financial statements that have been incurred but not yet paid, due within one year or the normal operating cycle, if longer.

No definition available.

Name:	ntra_OtherAccruedSundryExpensesCurrent
Namespace Prefix:	ntra_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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Carrying value as of the balance sheet date of obligations incurred through that date and payable to insurance entities to mitigate potential loss from various risks or to satisfy a promise to provide certain coverage's to employees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Name:	us-gaap_AccruedLiabilitiesCurrent
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Period Type:	instant

Carrying value as of the balance sheet date of obligations incurred through that date and payable for the marketing, trade and selling of the entity's goods and services. Marketing costs would include expenditures for planning and executing the conception, pricing, promotion, and distribution of ideas, goods, and services; costs of public relations and corporate promotions; and obligations incurred and payable for sales discounts, rebates, price protection programs, etc. offered to customers and under government programs. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

No definition available.

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

Carrying value as of the balance sheet date of obligations incurred through that date and payable for professional fees, such as for legal and accounting services received.

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

- References

No definition available.

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
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Name:	us-gaap_OperatingLeaseLiabilityCurrent
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Carrying value as of the balance sheet date of liabilities incurred through that date and payable for statutory sales and use taxes, including value added tax.

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-Publisher FASB
-Name Accounting Standards Codification
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