Earnings Per Share - Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net income									$ 4,165	$ 10,722
Dividends paid to preferred stockholders										(119)
Net income available to common stockholders									$ 4,165	$ 10,603
Denominator:
Weighted average shares outstanding - basic	41,262	41,351	41,127	39,482	38,501	36,094	32,068	31,297	40,808	34,513
Potential common shares - options (treasury stock method)									1,956	2,478
Weighted average shares outstanding - diluted	43,305	43,026	43,079	42,194	41,767	39,472	35,308	31,323	42,764	36,991
Shares excluded due to an exercise price greater than weighted average stock price for the period									98	88
Earnings per common share:
Basic	$ 0.02		$ 0.03	$ 0.05	$ 0.10	$ 0.10	$ 0.11		$ 0.10	$ 0.31
Diluted	$ 0.01		$ 0.03	$ 0.05	$ 0.09	$ 0.09	$ 0.10		$ 0.10	$ 0.29