Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical)	12 Months Ended
Dec. 31, 2014 USD ($) $ / shares
Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit)
Preferred stock (in dollars per share) \| $ / shares	$ 12.76
Preferred stock issuance costs \| $	$ 86,933

Represents the numerator used when converting the convertible preferred stock to common stock.

No definition available.

Name:	ntra_ConvertiblePreferredStockConversionNumeratorPerShare
Namespace Prefix:	ntra_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant