Earnings Per Share - Summary of Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net income (loss)	$ 10,183	$ (9,846)
Net income (loss) attributable to common stockholders - basic and diluted	$ 10,183	$ (9,846)
Denominator:
Basic	153,226,378	108,162,741
Diluted	156,018,731	108,162,741
Basic	$ 0.07	$ (0.09)
Diluted	$ 0.07	$ (0.09)