Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Financial assets:
Cash equivalents	$ 202,004	$ 105,299
Marketable securities:		59,099
Derivative instruments	1,745	903
Convertible note	1,000
Total financial assets	204,749	165,301
Financial liabilities:
Forward contracts	913	1,073
Total financial liabilities	913	1,073
Corporate notes/bonds
Financial assets:
Marketable securities:		59,099
Level 1
Financial assets:
Cash equivalents	202,004	105,299
Derivative instruments	0	0
Convertible note	0
Total financial assets	202,004	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	1,745	903
Convertible note	0
Total financial assets	1,745	903
Financial liabilities:
Forward contracts	913	1,073
Total financial liabilities	913	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