Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Class A [Member]	Common Class B [Member]	Common Stock [Member] Common Class A [Member]	Common Stock [Member] Common Class B [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Sep. 30, 2021	$ 1,427,164			$ 155			$ 1,615,236	$ (188,227)
Beginning balance (in shares) at Sep. 30, 2021				154,866,313
Beginning balance (in shares) at Sep. 30, 2021					100
Net income (loss)	52,525							52,525
Stock-based compensation	8,851						8,851
Exercise of vested stock options	4,923						4,923
Exercise of vested stock options (in shares)				214,041
Cancellation of restricted stock awards (in shares)				(10,573)
Issuance of common stock under employee stock plan, net of shares withheld for taxes	(429)						(429)
Issuance of common stock under employee stock plan, net of shares withheld for taxes (in shares)				(38,846)
Ending balance at Mar. 31, 2022	1,493,034			$ 155			1,628,581	(135,702)
Ending balance (in shares) at Mar. 31, 2022				155,108,627
Ending balance (in shares) at Mar. 31, 2022					100
Beginning balance at Dec. 31, 2021	1,451,151			$ 155			1,622,516	(171,520)
Beginning balance (in shares) at Dec. 31, 2021				155,032,377
Beginning balance (in shares) at Dec. 31, 2021					100
Net income (loss)	35,818							35,818
Stock-based compensation	4,881						4,881
Exercise of vested stock options	1,613						1,613
Exercise of vested stock options (in shares)				70,149
Cancellation of restricted stock awards (in shares)				(6,174)
Issuance of common stock under employee stock plan, net of shares withheld for taxes	(429)						(429)
Issuance of common stock under employee stock plan, net of shares withheld for taxes (in shares)				12,275
Ending balance at Mar. 31, 2022	1,493,034			$ 155			1,628,581	(135,702)
Ending balance (in shares) at Mar. 31, 2022				155,108,627
Ending balance (in shares) at Mar. 31, 2022					100
Beginning balance at Sep. 30, 2022	1,444,443			$ 155		$ (73,088)	1,630,378	(113,002)
Beginning balance (in shares) at Sep. 30, 2022				155,157,220
Beginning balance (in shares) at Sep. 30, 2022					100
Beginning balance (in shares) at Sep. 30, 2022		155,157,220	100			4,116,570
Net income (loss)	(9,563)							(9,563)
Other comprehensive income (loss)	(3,262)								$ (3,262)
Stock-based compensation	9,502						9,502
Exercise of vested stock options	1,901						1,901
Exercise of vested stock options (in shares)				82,646
Cancellation of restricted stock awards (in shares)				18,328
Issuance of common stock under employee stock plan, net of shares withheld for taxes	(460)						460
Issuance of common stock under employee stock plan, net of shares withheld for taxes (in shares)				(81,895)
Treasury stock purchases	(7,488)					$ 7,488
Treasury stock purchases (in shares)						(352,760)
Ending balance at Mar. 31, 2023	1,435,073			$ 155		$ (80,576)	1,641,321	(122,565)	(3,262)
Ending balance (in shares) at Mar. 31, 2023				155,303,433
Ending balance (in shares) at Mar. 31, 2023		155,303,433	100			4,469,330
Ending balance (in shares) at Mar. 31, 2023					100
Beginning balance at Dec. 31, 2022	1,412,772			$ 155		$ (80,576)	1,633,827	(138,838)	(1,796)
Beginning balance (in shares) at Dec. 31, 2022				155,196,865
Beginning balance (in shares) at Dec. 31, 2022					100
Beginning balance (in shares) at Dec. 31, 2022						4,469,330
Net income (loss)	16,273							16,273
Other comprehensive income (loss)	(1,466)								(1,466)
Stock-based compensation	5,593						5,593
Exercise of vested stock options	1,901						1,901
Exercise of vested stock options (in shares)				82,646
Cancellation of restricted stock awards (in shares)				3,665
Issuance of common stock under employee stock plan, net of shares withheld for taxes (in shares)				(27,587)
Ending balance at Mar. 31, 2023	$ 1,435,073			$ 155		$ (80,576)	$ 1,641,321	$ (122,565)	$ (3,262)
Ending balance (in shares) at Mar. 31, 2023				155,303,433
Ending balance (in shares) at Mar. 31, 2023		155,303,433	100			4,469,330
Ending balance (in shares) at Mar. 31, 2023					100