XML 52 R38.htm IDEA: XBRL DOCUMENT
v3.19.1

Capital Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands | 1 Months Ended | 3 Months Ended |
--- | --- | --- | ---
Oct. 31, 2018 | Jan. 31, 2018 | Sep. 30, 2016 | Mar. 31, 2019 | Mar. 31, 2018 | Dec. 31, 2018
Class of Stock [Line Items] |  |  |  |  |  |
Minimum percentage of outstanding common stock |  |  |  | 50.00% |  |
Fair value of warrants |  |  |  | $ 8,400 |  |
Proceeds from Warrant Exercises |  |  |  | $ 326 |  |
Proceeds from issuance of common stock |  |  |  |  | $ 5,732 |
Convertible preferred stock, shares outstanding |  |  |  | 400 |  | 400
Preferred stock par value |  |  |  | $ 0.01 |  | $ 0.01
Common Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Number of shares issued |  | 2,691,494 |  |  | 2,691,494 |
Common stock price per share |  | $ 2.35 |  |  |  |
Proceeds from issuance of common stock |  | $ 5,700 |  |  |  |
Private Placement [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Class of Warrants or right to purchase common stock |  |  | 13,333,334 |  |  |
Common stock price per share |  |  | $ 2.25 |  |  |
Class of Warrants or right to purchase common stock, exercise price |  |  | $ 2.25 |  |  |
Minimum percentage of outstanding common stock |  |  |  | 50.00% |  |
Fair value of warrants |  |  |  | $ 30,700 |  |
Gross proceeds from issuance of common stock, preferred stock and warrants |  |  | $ 30,000 |  |  |
Proceeds from issuance of common stock, preferred stock and warrants, net of issuance costs |  |  | $ 27,600 |  |  |
Conversion of preferred stock in to common stock, preferred stock converted |  |  | 10,737,275 | 444.44 |  |
Warrants granted to placement agent |  |  | 133,333 |  |  |
Warrants granted to placement agent,exercise price |  |  | $ 2.25 |  |  |
Warrants expiry period |  |  |  | 5 years |  |
Warrants exercisable period |  |  |  | 6 months |  |
Preferred stock par value |  |  |  | $ 0.01 |  |
Private Placement [Member] | Series A Preferred Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Number of shares issued |  |  | 24,158.8693 |  |  |
Convertible preferred stock, shares outstanding |  |  |  | 400.4910 |  |
Private Placement [Member] | Common Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Number of shares issued |  |  | 2,596,059 |  |  |
Private Placement [Member] | Common Stock [Member] | Series A Preferred Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Conversion of preferred stock in to common stock, preferred stock converted |  |  |  | 177,996 |  |
The Equity Distribution Agreement [Member] | Common Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Number of shares issued |  |  |  | 0 | 0 |
Underwritten Public Offering [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Class of Warrants or right to purchase common stock | 19,616,250 |  |  |  |  |
Gross proceeds from offering, before deducting underwriting discounts and commissions and offering expenses | $ 17,000 |  |  |  |  |
Class of Warrants or right to purchase common stock, exercise price | $ 0.70 |  |  |  |  |
Warrants exercisable term | 5 years |  |  |  |  |
Underwritten Public Offering [Member] | Common Stock And Warrants [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Common stock price per share | $ 0.65 |  |  |  |  |
Underwritten Public Offering [Member] | Common Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Number of shares issued | 26,155,000 |  |  |  |  |
Maximum [Member] | The Equity Distribution Agreement [Member] | Common Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Aggregate offering price of shares |  |  |  |  | $ 10,000 |
Members of Board of Directors [Member] | Private Placement [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Class of Warrants or right to purchase common stock |  |  |  | 1,422,221 |  |
Class of Warrants or right to purchase common stock, exercise price |  |  |  | $ 2.25 |  |
Members of Board of Directors [Member] | Private Placement [Member] | Series A Preferred Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Number of shares issued |  |  |  | 2,563.1439 |  |
Members of Board of Directors [Member] | Private Placement [Member] | Common Stock [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Number of shares issued |  |  |  | 283,046 |  |
Two Thousand Eighteen Warrants [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Class of Warrants or right to purchase common stock, exercise price |  |  |  | $ 0.70 |  |
Warrant reduced exercise price |  |  |  | $ 0.01 |  |
Proceeds from Warrant Exercises |  |  |  | $ 200 |  |
Two Thousand Sixteen Warrants [Member] |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |
Class of Warrants or right to purchase common stock |  |  |  | 508,714 |  |
Class of Warrants or right to purchase common stock, exercise price |  |  |  | $ 2.25 |  |
Warrant reduced exercise price |  |  |  | $ 0.01 |  |
Proceeds from Warrant Exercises |  |  |  | $ 100 |  |

X
- Definition Beneficial ownership minimum percentage of outstanding common stock. + References No definition available. + Details
Name: | hsgx_BeneficialOwnershipMinimumPercentageOfOutstandingCommonStock
Namespace Prefix: | hsgx_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Class of warrant or right exercisable expiration period. + References No definition available. + Details
Name: | hsgx_ClassOfWarrantOrRightExercisableExpirationPeriod
Namespace Prefix: | hsgx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Class of warrant or right exercisable period. + References No definition available. + Details
Name: | hsgx_ClassOfWarrantOrRightExercisablePeriod
Namespace Prefix: | hsgx_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Class of warrant or right exercise price of warrants or rights issued for service. + References No definition available. + Details
Name: | hsgx_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRightsIssuedForService
Namespace Prefix: | hsgx_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Class of warrant or right number of securities called by warrants or rights issued for service. + References No definition available. + Details
Name: | hsgx_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRightsIssuedForService
Namespace Prefix: | hsgx_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Class Of Warrant Or Right Reduced Exercise Price + References No definition available. + Details
Name: | hsgx_ClassOfWarrantOrRightReducedExercisePrice
Namespace Prefix: | hsgx_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Expected aggregate offering from issuance of common stock. + References No definition available. + Details
Name: | hsgx_ExpectedAggregateOfferingFromIssuanceOfCommonStock
Namespace Prefix: | hsgx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Gross Proceeds From Issuance Of Common Stock And Warrants + References No definition available. + Details
Name: | hsgx_GrossProceedsFromIssuanceOfCommonStockAndWarrants
Namespace Prefix: | hsgx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Gross proceeds from issuance of common stock, preferred stock and warrants. + References No definition available. + Details
Name: | hsgx_GrossProceedsFromIssuanceOfCommonStockPreferredStockAndWarrants
Namespace Prefix: | hsgx_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ClassOfStockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)(4)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)(2)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of shares converted in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4313-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586 + Details
Name: | us-gaap_ConversionOfStockSharesConverted1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_PreferredStockParOrStatedValuePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_PreferredStockSharesOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash inflow from the additional capital contribution to the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Proceeds from issuance of capital stock which provides for a specific dividend that is paid to the shareholders before any dividends to common stockholder, which takes precedence over common stockholders in the event of liquidation and from issuance of rights to purchase common shares at a predetermined price. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfPreferredStockPreferenceStockAndWarrants
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow associated with the amount received from holders exercising their stock warrants. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromWarrantExercises
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Per share or per unit amount of equity securities issued. + References No definition available. + Details
Name: | us-gaap_SharesIssuedPricePerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of new stock issued during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
Name: | us-gaap_WarrantsAndRightsOutstandingTerm
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fair value portion of warrants not settleable in cash classified as equity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258 + Details
Name: | us-gaap_WarrantsNotSettleableInCashFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=us-gaap_PrivatePlacementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesAPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=hsgx_TheEquityDistributionAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=hsgx_UnderwrittenPublicOfferingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=hsgx_CommonStockAndWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TitleOfIndividualAxis=hsgx_MembersOfBoardOfDirectorsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=hsgx_TwoThousandEighteenWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ClassOfWarrantOrRightAxis=hsgx_TwoThousandSixteenWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |