Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Sep. 30, 2019
Financial assets:
Cash equivalents	[1]	$ 105,299	$ 108,020
Marketable securities:		59,099	57,435
Forward contracts		903	3,064
Financial assets, fair value		165,301	168,519
Financial liabilities:
Forward contracts		1,073	2,771
Financial liabilities, fair value		1,073	2,771
Corporate notes/bonds
Financial assets:
Marketable securities:		59,099	56,436
Commercial paper
Financial assets:
Marketable securities:			999
Level 1
Financial assets:
Cash equivalents	[1]	105,299	108,020
Forward contracts		0	0
Financial assets, fair value		164,398	164,456
Financial liabilities:
Forward contracts		0	0
Financial liabilities, fair value		0	0
Level 1 | Corporate notes/bonds
Financial assets:
Marketable securities:		59,099	56,436
Level 1 | Commercial paper
Financial assets:
Marketable securities:			0
Level 2
Financial assets:
Cash equivalents	[1]	0	0
Forward contracts		903	3,064
Financial assets, fair value		903	4,063
Financial liabilities:
Forward contracts		1,073	2,771
Financial liabilities, fair value		1,073	2,771
Level 2 | Corporate notes/bonds
Financial assets:
Marketable securities:		0	0
Level 2 | Commercial paper
Financial assets:
Marketable securities:			999
Level 3
Financial assets:
Cash equivalents	[1]	0	0
Forward contracts		0	0
Financial assets, fair value		0	0
Financial liabilities:
Forward contracts		0	0
Financial liabilities, fair value		0	0
Level 3 | Corporate notes/bonds
Financial assets:
Marketable securities:		$ 0	0
Level 3 | Commercial paper
Financial assets:
Marketable securities:			$ 0

[1] Money market funds and time deposits.