Equity - Additional Information (Detail) $ / shares in Units, $ in Thousands |
12 Months Ended | |||
|---|---|---|---|---|
|
Jul. 02, 2018
USD ($)
$ / shares
shares
|
Jun. 15, 2018
shares
|
Dec. 31, 2018
USD ($)
shares
|
Dec. 31, 2017
USD ($)
$ / shares
shares
|
|
| Class of Stock [Line Items] | ||||
| Net proceeds from initial public offering | $ | $ 52,313 | |||
| Preferred stock, authorized | 10,000,000 | 10,000,000 | 0 | |
| Number of common stock repurchased | 1,341,216 | |||
| Stock price per share of common stock repurchased | $ / shares | $ 6.89 | |||
| Value of common stock repurchased | $ | $ 9,200 | |||
| Class A Common Stock [Member] | ||||
| Class of Stock [Line Items] | ||||
| Common stock, shares authorized | 220,000,000 | 220,000,000 | 30,004,760 | |
| Shares of common stock issued and sold | 3,125,000 | |||
| Common stock, voting right | Class A common stock entitles the holder to one vote for each share | |||
| Conversion of stock, shares issued | 4,116,404 | 24,000 | ||
| Class A Common Stock [Member] | Initial Public Offering (IPO) [Member] | ||||
| Class of Stock [Line Items] | ||||
| Shares of common stock issued and sold | 3,125,000 | |||
| Public offering price, per share | $ / shares | $ 18.00 | |||
| Net proceeds from initial public offering | $ | $ 48,600 | |||
| Class B Common Stock [Member] | ||||
| Class of Stock [Line Items] | ||||
| Common stock, shares authorized | 30,000,000 | 30,000,000 | 27,566,096 | |
| Common stock, voting right | Class B common stock entitles the holder to ten votes for each share | |||
| Common stock, conversion features | Each share of Class B common stock is convertible into one share of Class A common stock at the option of the holder at any time. Each share of Class B common stock held by a stockholder shall automatically convert into one fully paid and non-assessable share of Class A common stock nine months after the death or incapacity of the holder of such Class B common stock. | |||
| Conversion of stock, shares converted | 4,116,404 | 24,000 | ||
| Conversion of stock, shares issued | 12,596,064 | |||
| Forward Stock Split [Member] | ||||
| Class of Stock [Line Items] | ||||
| Forward stock split description | Eight-for-one forwardstock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company's Preferred Stock. | |||
| Forward stock split ratio | 8 | |||
| Common stock, shares authorized | 57,570,856 | |||