Capital Management - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Oct. 31, 2016
Equity [Abstract]
Share repurchase program, new limit amount						$ 25,000,000.0
Shares repurchased under the program			0
Shares repurchased	1,258,250	1,258,250	1,258,250	1,258,250
Shares repurchased, value	$ 22,370,000	$ 22,370,000	$ 22,370,000	$ 22,370,000
Shares repurchased, average price			$ 17.78
Quarterly dividend per share	$ 0.27	$ 0.25	0.27	$ 0.25	$ 0.22
Extraordinary dividends declared per share	$ 3.50	$ 3.50	$ 3.50	$ 3.50	$ 3.50