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Common Stock and Warrants - Additional Information (Details) $ / shares in Units, $ / shares in Units, $ in Millions |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 Months Ended | 12 Months Ended |
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Dec. 31, 2018 CAD ($) shares | Nov. 30, 2018 USD ($) $ / shares shares | Nov. 19, 2018 USD ($) $ / shares shares | Apr. 24, 2018 USD ($) $ / shares | Apr. 24, 2018 USD ($) $ / shares shares | Apr. 13, 2018 USD ($) $ / shares shares | Apr. 02, 2018 USD ($) | Apr. 01, 2018 USD ($) | 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. 31, 2017 USD ($) Tranche $ / shares shares | Dec. 31, 2018 USD ($) $ / shares shares | Dec. 31, 2017 USD ($) Tranche $ / shares shares | Apr. 13, 2018 $ / shares shares
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares authorized | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 150,000,000 |  |
Common stock, par value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.001 |  |
Preferred stock, shares authorized | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | 10,000,000 | 0 |
Preferred stock, par value | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.001 | $ 0.001 | $ 0.001 |
Common share, voting rights |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | one vote per share |  |
Common share, dividends declared |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 0 |  |
Share issuance cost and commission paid |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 3,161,000 | $ 1,248,000 |
Gian (loss) change in fair value of derivative financial instruments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | (3,577,000) | (3,443,000) |
Gross proceeds from issuance of common stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 38,526,000 | $ 20,878,000 |
Class of warrants exercised | shares | 70,900 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds received from exercise of outstanding warrants | $ 0.9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Derivative Financial Instruments Liabilities |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of warrants |  |  |  |  |  |  | $ 2,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants Expiration Date, April 18, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant exercisable price per share | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12.25 |  |
Warrants expiration date |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Dec. 28, 2020 |  |
April 2016 Offering |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of units |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7,200,000 |  |  |  |  |
Price per share | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 5.00 |  |  |  |
Warrant exercisable price per share | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7.50 |  |  |  |
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 |  |  |  |  |
Gian (loss) change in fair value of derivative financial instruments |  |  |  |  |  |  |  | $ (3,300,000) |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in derivative financial instruments |  |  |  |  |  |  |  | 4,700,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Reduction in additional paid in capital |  |  |  |  |  |  |  | $ 1,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |
April 2016 Offering | Warrants Expiration Date, April 18, 2019 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Description of units issued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Each Unit consists of one share of common stock 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 | (per share) |  | $ 8.25 |  | $ 7.47 | $ 7.47 |  |  |  |  |  |  |  |  |  | $ 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 |  |  |  |  |  |  |
Gross proceeds from issuance of common stock |  | $ 2,600,000 |  |  | $ 2,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Over-Allotment Option | Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of common stock in public offering | shares |  | 318,182 |  |  | 321,285 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 |  |
Short Form Prospectus Offering in Canada and U.S. Private Placement and Over-Allotment Option |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gian (loss) change in fair value of derivative financial instruments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 100,000 |  |
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 |  | $ 9.80 |
Description of units issued |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | Each unit consisted of one share of common stock and one share purchase warrant, and was sold at a price of $9.80 per unit. |  |
Number of common stock converted by each warrant | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1 |  | 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 |  | 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 |  |  |  |  |  |  |  |  |  |  |  |
April 2018 Offering |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Price per share | $ / shares |  |  |  |  |  | $ 7.47 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrant exercisable price per share | $ / shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 12.25
Warrants expiration date |  |  |  |  |  | Apr. 10, 2021 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of common stock converted by each warrant | shares |  |  |  |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1
Gross proceeds from issuance of common stock |  |  |  |  |  | $ 16,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Warrants to purchase number of common stock, shares | shares |  |  |  |  |  | 2,141,900 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,141,900
Underwriting discounts and commissions paid |  |  |  | $ 1,100,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Offering expenses incurred |  |  |  | 1,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds from offering |  |  |  | 16,300,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Underwriting Discounts And Offering Expenses |  |  |  | $ 800,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of warrants at issuance |  |  |  |  |  | $ 7,400,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
April 2018 Offering | Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of common stock in public offering | shares |  |  |  |  |  | 2,141,900 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
November 2018 Offering |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Price per share | $ / shares |  |  | $ 8.25 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from issuance of common stock |  |  | $ 17,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Underwriting discounts and commissions paid |  | $ 1,200,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Offering expenses incurred |  | 700,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net proceeds from offering |  | $ 18,300,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accrued share issuance cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 100,000 |  |
November 2018 Offering | Common Stock |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule Of Stockholders Equity [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Issuance of common stock in public offering | shares |  |  | 2,121,212 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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