Common Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jun. 25, 2018	Jul. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Common stock, shares authorized			150,000,000	150,000,000
Common stock, par value			$ 0.0001	$ 0.0001
Undesignated preferred stock			10,000	10,000
Undesignated shares of preferred stock outstanding			0	0
Cash dividends			$ 0
Net proceeds from issuance of common stock			$ 129,465	$ 104,013
IPO [Member]
Class of Stock [Line Items]
Common stock, shares issued and sold	5,247,958
Issuance price per shares	$ 19.00
Net proceeds from issuance of common stock	$ 90,103
Net proceeds after deducting underwriting discounts and commissions and offering costs	6,980
Other offering expenses	$ 2,628
Over-Allotment Option [Member]
Class of Stock [Line Items]
Common stock, shares issued and sold	787,193
Net proceeds from issuance of common stock	$ 13,910
Net proceeds after deducting underwriting discounts and commissions and offering costs	1,047
Other offering expenses	$ 104,013
Over-Allotment Option [Member] | Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares issued and sold		975,000
July 2019 Follow-on Offering [Member]
Class of Stock [Line Items]
Net proceeds from issuance of common stock		$ 129,500
July 2019 Follow-on Offering [Member] | Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares issued and sold		7,475,000
Issuance price per shares		$ 18.50