Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Financial assets:
Cash equivalents	$ 115,533	$ 105,299
Marketable securities:		59,099
Derivative instruments	6,846	903
Convertible note	1,000
Total financial assets	123,379	165,301
Financial liabilities:
Forward contracts	4,259	1,073
Total financial liabilities	4,259	1,073
Corporate notes/bonds
Financial assets:
Marketable securities:		59,099
Level 1
Financial assets:
Cash equivalents	115,533	105,299
Derivative instruments	0	0
Convertible note	0
Total financial assets	115,533	164,398
Financial liabilities:
Forward contracts	0	0
Total financial liabilities	0	0
Level 1 | Corporate notes/bonds
Financial assets:
Marketable securities:		59,099
Level 2
Financial assets:
Cash equivalents	0	0
Derivative instruments	6,846	903
Convertible note	0
Total financial assets	6,846	903
Financial liabilities:
Forward contracts	4,259	1,073
Total financial liabilities	4,259	1,073
Level 2 | Corporate notes/bonds
Financial assets:
Marketable securities:		0
Level 3
Financial assets:
Cash equivalents	0	0
Derivative instruments	0	0
Convertible note	1,000
Total financial assets	1,000	0
Financial liabilities:
Forward contracts	0	0
Total financial liabilities	$ 0	0
Level 3 | Corporate notes/bonds
Financial assets:
Marketable securities:		$ 0