CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Statement Of Financial Position [Abstract]
Accounts receivable allowances	$ 538	$ 1,394
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	560,000,000	560,000,000
Common stock, shares issued	37,780,000	36,842,000
Common stock, shares outstanding	37,780,000	36,842,000