XML 48 R37.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Share Based Payments - Summary of Stock Options Outstanding and Exercisable (Detail) - $ / shares | 3 Months Ended |
--- | --- | ---
Mar. 31, 2018 | Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 2,368,646 | 2,448,646
Exercise Price | $ 7.50 | $ 7.35
Number of Options Exercisable | 1,371,739 |
Employee and Director Stock Options |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 2,016,646 |
Number of Options Exercisable | 1,110,739 |
Employee and Director Stock Options | Option One |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 360,000 |
Expiration Date | Jun. 18, 2019 |
Options Outstanding Remaining Contractual Life (In Years) | 1 year 2 months 19 days |
Exercise Price | $ 3.00 |
Grant Date Fair Value | $ 1.00 |
Number of Options Exercisable | 360,000 |
Employee and Director Stock Options | Option Two |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 80,000 |
Expiration Date | Jun. 18, 2019 |
Options Outstanding Remaining Contractual Life (In Years) | 1 year 2 months 19 days |
Exercise Price | $ 3.00 |
Grant Date Fair Value | $ 1.32 |
Number of Options Exercisable | 80,000 |
Employee and Director Stock Options | Option Three |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 20,000 |
Expiration Date | Dec. 08, 2019 |
Options Outstanding Remaining Contractual Life (In Years) | 1 year 8 months 8 days |
Exercise Price | $ 14.60 |
Grant Date Fair Value | $ 6.55 |
Number of Options Exercisable | 20,000 |
Employee and Director Stock Options | Option Four |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 80,000 |
Expiration Date | Dec. 08, 2019 |
Options Outstanding Remaining Contractual Life (In Years) | 1 year 8 months 8 days |
Exercise Price | $ 14.80 |
Grant Date Fair Value | $ 6.46 |
Number of Options Exercisable | 80,000 |
Employee and Director Stock Options | Option Five |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 20,000 |
Expiration Date | Mar. 16, 2020 |
Options Outstanding Remaining Contractual Life (In Years) | 1 year 11 months 15 days |
Exercise Price | $ 16.00 |
Grant Date Fair Value | $ 7.09 |
Number of Options Exercisable | 20,000 |
Employee and Director Stock Options | Option Six |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 8,500 |
Expiration Date | Aug. 14, 2020 |
Options Outstanding Remaining Contractual Life (In Years) | 2 years 4 months 17 days |
Exercise Price | $ 4.90 |
Grant Date Fair Value | $ 1.94 |
Number of Options Exercisable | 8,500 |
Employee and Director Stock Options | Option Seven |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 150,000 |
Expiration Date | Oct. 21, 2020 |
Options Outstanding Remaining Contractual Life (In Years) | 2 years 6 months 21 days |
Exercise Price | $ 4.20 |
Grant Date Fair Value | $ 1.80 |
Number of Options Exercisable | 112,500 |
Employee and Director Stock Options | Option Eight |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 20,000 |
Expiration Date | Dec. 31, 2020 |
Options Outstanding Remaining Contractual Life (In Years) | 2 years 9 months 3 days |
Exercise Price | $ 6.20 |
Grant Date Fair Value | $ 2.49 |
Number of Options Exercisable | 20,000 |
Employee and Director Stock Options | Option Nine |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 595,000 |
Expiration Date | Jul. 13, 2020 |
Options Outstanding Remaining Contractual Life (In Years) | 2 years 3 months 14 days |
Exercise Price | $ 6.95 |
Grant Date Fair Value | $ 3.23 |
Number of Options Exercisable | 396,666 |
Employee and Director Stock Options | Option Ten |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 20,000 |
Expiration Date | Aug. 08, 2020 |
Options Outstanding Remaining Contractual Life (In Years) | 2 years 4 months 9 days |
Exercise Price | $ 6.55 |
Grant Date Fair Value | $ 3.23 |
Number of Options Exercisable | 10,000 |
Employee and Director Stock Options | Option Eleven |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 617,000 |
Expiration Date | Apr. 17, 2027 |
Options Outstanding Remaining Contractual Life (In Years) | 9 years 18 days |
Exercise Price | $ 10.80 |
Grant Date Fair Value | $ 7.76 |
Employee and Director Stock Options | Option Twelve |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 6,146 |
Expiration Date | May 18, 2027 |
Options Outstanding Remaining Contractual Life (In Years) | 9 years 1 month 20 days |
Exercise Price | $ 10.00 |
Grant Date Fair Value | $ 5.23 |
Number of Options Exercisable | 3,073 |
Employee and Director Stock Options | Option Thirteen |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 10,000 |
Expiration Date | May 18, 2027 |
Options Outstanding Remaining Contractual Life (In Years) | 9 years 1 month 20 days |
Exercise Price | $ 10.00 |
Grant Date Fair Value | $ 7.63 |
Employee and Director Stock Options | Option Fourteen |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 30,000 |
Expiration Date | Aug. 08, 2027 |
Options Outstanding Remaining Contractual Life (In Years) | 9 years 4 months 9 days |
Exercise Price | $ 13.15 |
Grant Date Fair Value | $ 8.86 |
Non-employee Stock Options |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 352,000 |
Number of Options Exercisable | 261,000 |
Non-employee Stock Options | Option One |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 80,000 |
Expiration Date | Jun. 18, 2019 |
Options Outstanding Remaining Contractual Life (In Years) | 1 year 2 months 19 days |
Exercise Price | $ 3.00 |
Grant Date Fair Value | $ 1.32 |
Number of Options Exercisable | 80,000 |
Non-employee Stock Options | Option Two |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 30,000 |
Expiration Date | Dec. 08, 2019 |
Options Outstanding Remaining Contractual Life (In Years) | 1 year 8 months 8 days |
Exercise Price | $ 14.60 |
Grant Date Fair Value | $ 8.25 |
Number of Options Exercisable | 30,000 |
Non-employee Stock Options | Option Three |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 82,000 |
Expiration Date | Oct. 03, 2020 |
Options Outstanding Remaining Contractual Life (In Years) | 2 years 9 months 3 days |
Exercise Price | $ 6.75 |
Grant Date Fair Value | $ 4.00 |
Number of Options Exercisable | 41,000 |
Non-employee Stock Options | Option Four |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 110,000 |
Expiration Date | Oct. 28, 2020 |
Options Outstanding Remaining Contractual Life (In Years) | 2 years 6 months 3 days |
Exercise Price | $ 4.20 |
Grant Date Fair Value | $ 2.20 |
Number of Options Exercisable | 110,000 |
Non-employee Stock Options | Option Five |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 20,000 |
Expiration Date | May 18, 2027 |
Options Outstanding Remaining Contractual Life (In Years) | 9 years 1 month 20 days |
Exercise Price | $ 10.00 |
Grant Date Fair Value | $ 8.69 |
Non-employee Stock Options | Option Six |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 15,000 |
Expiration Date | Aug. 08, 2027 |
Options Outstanding Remaining Contractual Life (In Years) | 9 years 4 months 9 days |
Exercise Price | $ 13.15 |
Grant Date Fair Value | $ 11.70 |
Non-employee Stock Options | Option Seven |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |
Number of Options Outstanding | 15,000 |
Expiration Date | Nov. 06, 2027 |
Options Outstanding Remaining Contractual Life (In Years) | 9 years 7 months 9 days |
Exercise Price | $ 20.65 |
Grant Date Fair Value | $ 19.93 |

X
- Definition Expiration date of the option. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Footnote 5 + Details
Name: | invest_InvestmentOptionsExpirationDate
Namespace Prefix: | invest_
Data Type: | xbrli:dateItemType
Balance Type: | na
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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=hsdt_EmployeeAndDirectorStockOptionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionSixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionSevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionEightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionNineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionTenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionElevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionTwelveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionThirteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=hsdt_OptionFourteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AwardTypeAxis=hsdt_NonEmployeeStockOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |