Common Stock and Warrants - Additional Information (Details) $ / shares in Units, $ / shares in Units, $ in Millions												1 Months Ended	3 Months Ended
	Mar. 31, 2019 CAD ($) shares	Nov. 30, 2018 USD ($) $ / shares shares	Nov. 19, 2018 USD ($) $ / shares shares	Apr. 24, 2018 USD ($) $ / shares shares	Apr. 24, 2018 USD ($) $ / shares	Apr. 13, 2018 USD ($) $ / shares shares	Dec. 29, 2017 USD ($) shares	Dec. 28, 2017 USD ($) shares	Dec. 22, 2017 USD ($) shares	Apr. 18, 2016 USD ($) shares	Apr. 18, 2016 $ / shares shares	Dec. 31, 2017 USD ($) Tranche $ / shares shares	Mar. 31, 2019 USD ($) $ / shares shares	Mar. 31, 2018 USD ($)	Dec. 31, 2018 $ / shares shares	Apr. 13, 2018 $ / shares shares
Schedule Of Stockholders Equity [Line Items]
Common stock, shares authorized | shares													150,000,000		150,000,000
Common stock, par value | $ / shares													$ 0.001		$ 0.001
Preferred stock, shares authorized | shares													10,000,000		10,000,000
Preferred stock, par value | $ / shares													$ 0.001		$ 0.001
Common share, voting rights													one vote per share
Common share, dividends declared													$ 0
Share issuance cost and commission paid													$ 52,000	$ 73,000
Warrants outstanding | shares													3,987,984
Class of warrants exercised | shares	70,900
Proceeds received from exercise of outstanding warrants	$ 0.9
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
Warrants outstanding | shares													171,020
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 share 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
Warrants outstanding | shares													944,379
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 of the Company (a “Common Share’) and one-half of one Common Share purchase warrant (each whole warrant, a “Warrant”).
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 common stock and one share purchase warrant, and was sold at a price of $9.80 per unit.
Number of common share 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 tranches | Tranche												3
Number of shares issued in transaction | shares												646,016
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 share converted by each warrant | shares						1										1
Warrants to purchase number of common stock, shares | shares						2,141,900										2,141,900
Gross proceeds from issuance of common stock						$ 16,000,000
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
Over-Allotment Option
Schedule Of Stockholders Equity [Line Items]
Price per share | $ / shares		$ 8.25		$ 7.47	$ 7.47
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
November 2018 Offering
Schedule Of Stockholders Equity [Line Items]
Price per share | $ / shares			$ 8.25
Share issuance cost and commission paid													$ 100,000
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
November 2018 Offering | Common Stock
Schedule Of Stockholders Equity [Line Items]
Issuance of common stock in public offering | shares			2,121,212