Business and Nature of Operations - Additional Information (Details) - USD ($)	1 Months Ended		12 Months Ended
	Jan. 31, 2019	Apr. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Business And Nature Of Operations [Line Items]
Common shares sold pursuant to exercise of employee stock option			778,370	497,175
Follow-On Public Offering [Member]
Business And Nature Of Operations [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares		553,825
Issuance of common stock, public offering, price per share		$ 19.85
Proceeds from issuance of common stock		$ 9,900,000
Follow-On Public Offering [Member] | Subsequent Event [Member]
Business And Nature Of Operations [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares	2,645,000
Issuance of common stock, public offering, price per share	$ 55.25
Proceeds from issuance of common stock	$ 139,700,000
Underwriter Purchase Option [Member]
Business And Nature Of Operations [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares		26,825
Underwriter Purchase Option [Member] | Subsequent Event [Member]
Business And Nature Of Operations [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares	345,000
Selling Stockholders [Member]
Business And Nature Of Operations [Line Items]
Issuance of common stock, public offering, net of issuance costs, shares		3,162,164
Common shares sold pursuant to exercise of employee stock option		73,000
Proceeds from issuance of common stock		$ 0