Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders Equity (Deficit) (Parenthetical) $ in Millions	9 Months Ended
Sep. 30, 2015 USD ($)
Statement Of Stockholders Equity [Abstract]
Initial public offering, issuance cost	$ 5.9

Issuance of common stock from initial public offering, issuance costs.

No definition available.

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Namespace Prefix:	htgm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration