XML 39 R28.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Common Stock and Warrants - Additional Information (Detail) |  |  |  |  |  |  |  |  |  | 1 Months Ended | 3 Months Ended |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Dec. 29, 2017 USD ($) shares | Dec. 28, 2017 USD ($) shares | Dec. 22, 2017 USD ($) shares | Jun. 28, 2017 USD ($) shares | Feb. 16, 2017 USD ($) shares | May 02, 2016 USD ($) shares | May 02, 2016 $ / shares shares | Apr. 18, 2016 USD ($) shares | Apr. 18, 2016 $ / shares shares | Dec. 29, 2015 USD ($) $ / shares shares | Nov. 30, 2015 $ / shares shares | Dec. 31, 2017 USD ($) Tranche $ / shares shares | Nov. 30, 2017 USD ($) $ / shares shares | Mar. 31, 2018 USD ($) $ / shares shares | Mar. 31, 2017 USD ($) | Mar. 31, 2018 $ / shares | Oct. 09, 2015 USD ($)
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class A common share, voting rights |  |  |  |  |  |  |  |  |  |  |  |  |  | One vote per share |  |  |
Class A common share, dividends declared |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  |  |
Share issuance cost and commission paid |  |  |  |  |  |  |  |  |  |  |  |  |  | 73,000 | $ 1,239,000 |  |
Gross proceeds from issuance of common stock |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 | $ 9,187,000 |  |
Warrants Expiration Date, April 18, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant exercisable price per share | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7.50 |
Warrants expiration date |  |  |  |  |  |  |  |  |  |  |  |  |  | Apr. 18, 2019 |  |  |
Short Form Prospectus Offering in Canada and U.S. Private Placement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant exercisable price per share | $ / shares |  |  |  |  |  |  |  |  | $ 7.50 |  |  |  |  |  |  |  |
Proceeds from issuance of units |  |  |  |  |  |  |  | $ 7,200,000 |  |  |  |  |  |  |  |  |
Price per share | $ / shares |  |  |  |  |  |  |  |  | $ 5.00 |  |  |  |  |  |  |  |
Warrants expiration date |  |  |  |  |  |  |  | Apr. 18, 2019 |  |  |  |  |  |  |  |  |
Number of common stock converted by each warrant | shares |  |  |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |
Share issuance cost and commission paid |  |  |  |  |  |  |  | $ 300,000 |  |  |  |  |  |  |  |  |
Options exercisable to purchase units | shares |  |  |  |  |  |  |  | 87,210 |  |  |  |  |  |  |  |  |
Options exercise price per unit | $ / shares |  |  |  |  |  |  |  |  | $ 5.00 |  |  |  |  |  |  |  |
Offering expiration period |  |  |  |  |  |  |  | 24 months |  |  |  |  |  |  |  |  |
Other cash issuance costs related to offering |  |  |  |  |  |  |  | $ 1,100,000 |  |  |  |  |  |  |  |  |
Short Form Prospectus Offering in Canada and U.S. Private Placement | Warrants Expiration Date, April 18, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Description of units issued |  |  |  |  |  |  |  |  |  |  |  |  |  | Each Unit consists of one Class A common share in the capital of the Company (a “Common Share’) and one half of one Common Share purchase warrant (each whole warrant, a “Warrant”). |  |  |
Over-Allotment Option |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of units |  |  |  |  |  | $ 8,100,000 |  |  |  |  |  |  |  |  |  |  |
Price per share | $ / shares |  |  |  |  |  |  | $ 5.00 |  |  |  |  |  |  |  |  |  |
Warrants expiration date |  |  |  |  |  | Apr. 18, 2019 |  |  |  |  |  |  |  |  |  |  |
Number of common stock converted by each warrant | shares |  |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |
Share issuance cost and commission paid |  |  |  |  |  | $ 100,000 |  |  |  |  |  |  |  |  |  |  |
Options exercisable to purchase units | shares |  |  |  |  |  | 13,081 |  |  |  |  |  |  |  |  |  |  |
Options exercise price per unit | $ / shares |  |  |  |  |  |  | $ 5.00 |  |  |  |  |  |  |  |  |  |
Offering expiration period |  |  |  |  |  | 24 months |  |  |  |  |  |  |  |  |  |  |
Number of shares issued in transaction | shares |  |  |  |  |  | 218,025 |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from issuance of units |  |  |  |  |  | $ 900,000 |  |  |  |  |  |  |  |  |  |  |
Over-Allotment Option | Warrants Expiration Date, April 18, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Description of units issued |  |  |  |  |  |  |  |  |  |  |  |  |  | Each over-allotment warrant entitles the holder thereof to acquire one additional over-allotment Common Share at an exercise price of CAD $7.50 on or before April 18, 2019 |  |  |
Public Offering | Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share issuance cost and commission paid |  |  |  |  | $ 1,200,000 |  |  |  |  |  |  |  |  |  |  |  |
Issuance of common stock in public offering | shares |  |  |  |  | 1,311,000 |  |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from issuance of common stock |  |  |  |  | $ 9,200,000 |  |  |  |  |  |  |  |  |  |  |  |
Private Placement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of units |  |  |  |  |  |  |  |  |  |  |  | $ 3,655,000 |  |  |  |  |
Number of shares issued in transaction | shares |  |  |  |  |  |  |  |  |  |  |  | 372,956 |  |  |  |  |
Private Placement | Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of units |  |  |  | $ 5,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Share issuance cost and commission paid |  |  |  | $ 9,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares issued in transaction | shares |  |  |  | 800,000 |  |  |  |  |  |  |  |  |  |  |  |  |
December 2017 Financing |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of units |  |  |  |  |  |  |  |  |  |  |  | $ 6,300,000 |  |  |  |  |
Price per share | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 9.80 |  |  |  |  |
Description of units issued |  |  |  |  |  |  |  |  |  |  |  |  |  | Each unit consisted of one share of Class A common stock of the Company at a price of $9.80 per share, and one share purchase warrant. |  |  |
Number of common stock converted by each warrant | shares |  |  |  |  |  |  |  |  |  |  |  | 1 |  |  |  |  |
Share issuance cost and commission paid |  |  |  |  |  |  |  |  |  |  |  | $ 100,000 |  |  |  |  |
Options exercise price per unit | $ / shares |  |  |  |  |  |  |  |  |  |  |  | $ 12.25 |  |  |  |  |
Offering expiration period |  |  |  |  |  |  |  |  |  |  |  | 36 months |  |  |  |  |
Number of shares issued in transaction | shares |  |  |  |  |  |  |  |  |  |  |  | 646,016 |  |  |  |  |
Number of tranches | Tranche |  |  |  |  |  |  |  |  |  |  |  | 3 |  |  |  |  |
December 2017 Financing | Tranche One |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of units |  |  | $ 2,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares issued in transaction | shares |  |  | 270,915 |  |  |  |  |  |  |  |  |  |  |  |  |  |
December 2017 Financing | Tranche Two |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of units |  | $ 1,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares issued in transaction | shares |  | 171,020 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
December 2017 Financing | Tranche Three |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of units | $ 2,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares issued in transaction | shares | 204,081 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
$2.0 million note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt conversion, converted instrument, shares issued | shares |  |  |  |  |  |  |  |  |  |  | 416,666 |  |  |  |  |  |
Common stock conversion price per share | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 4.80 |  |  |  |  |  |
Warrants exercisable | shares |  |  |  |  |  |  |  |  |  |  | 208,333 |  |  |  |  |  |
Warrant exercisable price per share | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 7.20 |  |  |  |  |  |
Warrants exercisable period |  |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |
Additional funding commitment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt conversion, original debt, amount |  |  |  |  |  |  |  |  |  | $ 5,000,000 |  |  |  |  |  |  |
Debt conversion, converted instrument, shares issued | shares |  |  |  |  |  |  |  |  |  | 1,111,111 |  |  |  |  |  |  |
Common stock conversion price per share | $ / shares |  |  |  |  |  |  |  |  |  | $ 4.50 |  |  |  |  |  |  |
Warrants exercisable | shares |  |  |  |  |  |  |  |  |  | 555,556 |  |  |  |  |  |  |
Warrant exercisable price per share | $ / shares |  |  |  |  |  |  |  |  |  | $ 6.75 |  |  |  |  |  |  |
Warrants exercisable period |  |  |  |  |  |  |  |  |  | 3 years |  |  |  |  |  |  |
A&B Company Limited |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Class of warrants exercised | shares |  |  |  |  |  |  |  |  |  |  |  |  | 208,333 | 555,556 |  |  |
Class of warrant or right exercise price per share | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  | $ 7.20 | $ 6.75 |  |  |
Proceeds received from exercise of outstanding warrants |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,500,000 | $ 3,800,000 |  |  |
A&B Company Limited | Private Placement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of units |  |  |  |  |  |  |  |  |  |  |  | $ 2,000,000 |  |  |  |  |
Number of shares issued in transaction | shares |  |  |  |  |  |  |  |  |  |  |  | 204,081 |  |  |  |  |
Asset Purchase Agreement | A&B Company Limited |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Convertible promissory note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7,000,000
Asset Purchase Agreement | A&B Company Limited | $2.0 million note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Convertible promissory note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,000,000
Asset Purchase Agreement | A&B Company Limited | Additional funding commitment |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Convertible promissory note |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 5,000,000

X
- Definition Class of warrant or right exercise price exercised of warrants or rights. + References No definition available. + Details
Name: | hsdt_ClassOfWarrantOrRightExercisePriceExercisedOfWarrantsOrRights
Namespace Prefix: | hsdt_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Class of warrant or right exercised. + References No definition available. + Details
Name: | hsdt_ClassOfWarrantOrRightExercised
Namespace Prefix: | hsdt_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Gross proceeds from issuance or sale of equity. + References No definition available. + Details
Name: | hsdt_GrossProceedsFromIssuanceOrSaleOfEquity
Namespace Prefix: | hsdt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of tranches. + References No definition available. + Details
Name: | hsdt_NumberOfTranches
Namespace Prefix: | hsdt_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Offering expiration period. + References No definition available. + Details
Name: | hsdt_OfferingExpirationPeriod
Namespace Prefix: | hsdt_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Options exercisable to purchase units. + References No definition available. + Details
Name: | hsdt_OptionsExercisableToPurchaseUnits
Namespace Prefix: | hsdt_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Options exercise price per unit. + References No definition available. + Details
Name: | hsdt_OptionsExercisePricePerUnit
Namespace Prefix: | hsdt_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Other cash issuance costs related to offering. + References No definition available. + Details
Name: | hsdt_OtherCashIssuanceCostsRelatedToOffering
Namespace Prefix: | hsdt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Schedule of stockholders equity. + References No definition available. + Details
Name: | hsdt_ScheduleOfStockholdersEquityLineItems
Namespace Prefix: | hsdt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Warrants exercisable. + References No definition available. + Details
Name: | hsdt_WarrantsExercisable
Namespace Prefix: | hsdt_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Warrants exercisable period. + References No definition available. + Details
Name: | hsdt_WarrantsExercisablePeriod
Namespace Prefix: | hsdt_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expiration date of warrants held. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column A + Details
Name: | invest_InvestmentWarrantsExpirationDate
Namespace Prefix: | invest_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 each warrant or right may be converted. For example, but not limited to, each warrant may be converted into two shares. + References No definition available. + Details
Name: | us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByEachWarrantOrRight
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Description of voting rights of common stock. Includes eligibility to vote and votes per share owned. Include also, if any, unusual voting rights. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644 + Details
Name: | us-gaap_CommonStockVotingRights
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04(13)) -URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_ConvertibleNotesPayable
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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 + Details
Name: | us-gaap_DebtConversionConvertedInstrumentSharesIssued1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 2: http://www.xbrl.org/2003/role/presentationRef -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_DebtConversionOriginalDebtAmount1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The price per share of the conversion feature embedded in the debt instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870 + Details
Name: | us-gaap_DebtInstrumentConvertibleConversionPrice1
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of paid and unpaid common stock dividends declared with the form of settlement in cash, stock and payment-in-kind (PIK). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 405 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817 + Details
Name: | us-gaap_DividendsCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash outflow for cost incurred directly with the issuance of an equity security. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfStockIssuanceCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The cash inflow from the additional capital contribution to the entity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The cash inflow from the issuance of common stock, preferred stock, treasury stock, stock options, and other types of equity. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOrSaleOfEquity
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 No definition available. + Details
Name: | us-gaap_ProceedsFromWarrantExercises
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Description of stock transaction which may include details of the offering (IPO, private placement), a description of the stock sold, percentage of subsidiary's or equity investee's stock sold, a description of the investors and whether the stock was issued in a business combination. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84161450&loc=SL4582445-111684 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=96868048&loc=SL4569655-111683 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=84161450&loc=SL4573702-111684 + Details
Name: | us-gaap_SaleOfStockDescriptionOfTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of shares issued or sold by the subsidiary or equity method investee per stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockPricePerShare
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://www.xbrl.org/2003/role/presentationRef -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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -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 Reference 4: http://www.xbrl.org/2003/role/presentationRef -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 + Details
Name: | us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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

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

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

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

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_SubsidiarySaleOfStockAxis=hsdt_DecemberTwoThousandSeventeenFinancingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

X
- Details
Name: | us-gaap_DebtInstrumentAxis=hsdt_TwoPointZeroMillionNoteMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=hsdt_AdditionalFundingCommitmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CounterpartyNameAxis=hsdt_AAndBCompanyLimitedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_TypeOfArrangementAxis=hsdt_AssetPurchaseAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |