Stockholders' Equity - Additional Information (Detail) - USD ($)	12 Months Ended			42 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Aug. 27, 2019	Apr. 11, 2018	Jul. 13, 2017
Schedule Of Capitalization Equity [Line Items]
Common stock, voting rights	Class B common stock is entitled to ten votes per share as compared to one vote per share for the Class A common stock
Cash dividend paid per share	$ 0.13	$ 0.20
Aggregate amount of cash dividends paid	$ 10,500,000	$ 17,000,000.0
Preferred stock, shares issued	0	0		0
Preferred stock, shares outstanding	0	0		0
Amount approved under share purchase					$ 45,000,000.0	$ 30,000,000.0	$ 15,000,000.0
Aggregate purchase price of repurchased shares	$ 525,000	$ 12,565,000	$ 13,812,000
Class A common stock
Schedule Of Capitalization Equity [Line Items]
Amount approved under share purchase					$ 15,000,000.0	$ 15,000,000.0
Number of shares repurchased	300,000	3,800,000	3,500,000	8,600,000
Average price of repurchased shares	$ 2.02	$ 3.30	$ 3.90	$ 3.76
Aggregate purchase price of repurchased shares	$ 500,000	$ 12,600,000	$ 13,800,000	$ 32,200,000