Description of the Business and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
	Jul. 27, 2020 USD ($) $ / shares shares	Dec. 31, 2020 Employee $ / shares shares	Dec. 31, 2020 USD ($) Employee Office $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares
Description Of Business And Basis Of Presentation [Line Items]
Entity formation, month and year			2013-11
Number of offices in which entity operates | Office			70
Entity number of employees | Employee		1,800	1,800
Common stock issued, shares | shares	1,786,739			42,415
Share price | $ / shares		$ 21.81	$ 21.81	$ 26.97	$ 20.65
Net proceeds from sale of common stock			$ 408	$ 1,509	$ 30
IPO
Description Of Business And Basis Of Presentation [Line Items]
Common stock issued, shares | shares	11,500,000	11,500,000	11,500,000
Share price | $ / shares	$ 15.00
Net proceeds from sale of common stock	$ 161,300
Underwriting discounts	11,200
Deferred offset	$ 4,400
Underwriters
Description Of Business And Basis Of Presentation [Line Items]
Common stock issued, shares | shares	1,500,000