Income Taxes - Reconciliation of Effective Tax Rate to Statutory Federal Rate (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Federal tax benefit at statutory rate	$ (2,512)	$ (9,259)	$ (13,608)
State tax provision (benefit), net of federal benefit	1,831	(10,808)	167
Foreign tax rate and other foreign related tax items	927	(3,285)	2,755
Stock-based compensation	(14,519)	(3,830)	3,368
Non-deductible expenditures	4,148	479	2,689
Executive compensation	5,049	6,445	1,662
Change in U.S. and foreign valuation allowance	126,917	(27,050)	176,624
Capital (losses) gains	(95,858)	10,443	(180,133)
Intangible property transfers	0	(14,800)	(24,691)
Uncertain tax positions	4,006	17,051	3,232
Base erosion and anti-abuse tax	(807)	4,297	2,880
Tax (credits) benefits	(18,857)	(9,989)	722
Foreign dividend	0	12,806	1,026
Debt repurchases	(5,050)	(3,442)	0
Other	133	74	109
Provision (benefit) for income taxes	$ 5,408	$ (30,868)	$ (23,198)

Effective Income Tax Rate Reconciliation, Base Erosion And Anti-Abuse Tax, Amount

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