Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jan. 31, 2021	Apr. 30, 2020
Statement Of Financial Position [Abstract]
Allowances for credit losses	$ 151	$ 1,038
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	74,153,528	73,526,790
Common stock, shares outstanding	53,249,177	55,359,928
Treasury stock, shares	20,904,351	18,166,862

Amount of allowance for credit loss on accounts receivable, classified as current.

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