Income Taxes - Components of Income Before Income Taxes and Equity in Earnings of Equity Method Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest [Abstract]
Domestic	$ (88,763)	$ (48,932)	$ (85,639)
Foreign	39,794	8,640	1,682
Loss before income taxes	$ (48,969)	$ (40,292)	$ (83,957)