Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		12 Months Ended
	Jan. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Stockholders Equity [Line Items]
Number of stock issued (in shares)	5,950,000
Additional shares granted to underwriters (in shares)	770,000
IPO [Member]
Schedule Of Stockholders Equity [Line Items]
Offering price (in dollars per share)	$ 22.00
Net proceeds from issuance	$ 30.9
Existing Stockholders [Member]
Schedule Of Stockholders Equity [Line Items]
Number of stock issued (in shares)	4,450,000
Parent [Member]
Schedule Of Stockholders Equity [Line Items]
Number of stock issued (in shares)	1,500,000
Common Stock [Member]
Schedule Of Stockholders Equity [Line Items]
Number of stock issued (in shares)		1,500,000
Common stock repurchased during period (in shares)			22,754
Aggregate amount paid for share repurchase			$ 0.4