XML 53 R39.htm IDEA: XBRL DOCUMENT
v3.19.1

Warrants - Schedule of Warrants to Purchase Common Stock Outstanding (Detail) | 3 Months Ended
--- | ---
Mar. 31, 2019 $ / shares shares
Warrants Issued September 2016 [Member] |
Class of Warrant or Right [Line Items] |
Issued | 2016-09
Warrants Outstanding,shares | shares | 508,714
Exercise Price | $ / shares | $ 2.25
Expiration | 2021-11
Warrants Issued March 2015 [Member] |
Class of Warrant or Right [Line Items] |
Issued | 2015-03
Warrants Outstanding,shares | shares | 3,699
Exercise Price | $ / shares | $ 9.75
Expiration | 2025-03
Warrants Issued July 2014 [Member] |
Class of Warrant or Right [Line Items] |
Issued | 2014-07
Warrants Outstanding,shares | shares | 6,566
Exercise Price | $ / shares | $ 7.99
Expiration | 2024-07
Warrants Issued July 2012 [Member] |
Class of Warrant or Right [Line Items] |
Issued | 2012-07
Warrants Outstanding,shares | shares | 52,046
Exercise Price | $ / shares | $ 0.01
Expiration | 2022-07

X
- Definition Class of warrant or right warrant expiration month and year. + References No definition available. + Details
Name: | hsgx_ClassOfWarrantOrRightWarrantExpirationMonthAndYear
Namespace Prefix: | hsgx_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Class of warrant or right warrant issued month and year. + References No definition available. + Details
Name: | hsgx_ClassOfWarrantOrRightWarrantIssuedMonthAndYear
Namespace Prefix: | hsgx_
Data Type: | xbrli:gYearMonthItemType
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 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_ClassOfWarrantOrRightLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number 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)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

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

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

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

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