Summary of Series B Convertible Preferred Stock and Accretion of Dividend (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Stockholders Equity [Line Items]
Dividends earned on Series B preferred stock	$ 298	$ 284
Series B Convertible Preferred Stock
Stockholders Equity [Line Items]
Balance at beginning of period	24,117	22,969
Dividends earned on Series B preferred stock	298	284
Balance at end of period	$ 24,415	$ 23,253
Number of shares at beginning of period	6,029	5,742
Cumulative dividends on Series B convertible preferred stock	75	71
Number of shares at end of period	6,104	5,813