Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022
Income Taxes [Line Items]
U.S. federal statutory rates	21.00%	21.00%	21.00%
Income tax expense (benefit)	$ 19,865	$ 112,075	$ 2,376
Deferred tax assets valuation allowance	162,966	126,860
Uncertain tax positions	85,172	76,590	87,144
Uncertain tax positions cumulative translation adjustments	5,000	(13,200)
Increases related to tax positions taken from prior periods		2,277
Interest related to uncertain tax positions	600	(300)	300
Recognized interest income	$ 4,200	3,500
Minimum
Income Taxes [Line Items]
Operating loss carryforwards expiration year	2026
Minimum | Research and Development
Income Taxes [Line Items]
Operating loss carryforwards expiration year	2024
Maximum | Research and Development
Income Taxes [Line Items]
Operating loss carryforwards expiration year	2041
U.S. Federal
Income Taxes [Line Items]
Net operating loss carryforwards		43,600
U.S. Federal | Research and Development
Income Taxes [Line Items]
Net operating loss carryforwards	$ 7,600	10,100
Uncertain tax positions	7,400	8,100
U.S. Federal | Unlimited Period
Income Taxes [Line Items]
Net operating loss carryforwards		42,800
State
Income Taxes [Line Items]
Net operating loss carryforwards	8,400	11,900
State | Research and Development
Income Taxes [Line Items]
Net operating loss carryforwards	300	200
Netherlands
Income Taxes [Line Items]
Net operating loss carryforwards	350,500	157,400
Domestic
Income Taxes [Line Items]
Deferred tax assets valuation allowance	8,200	8,200
Foreign
Income Taxes [Line Items]
Deferred tax assets valuation allowance	154,800	118,700		$ 107,600
Net operating loss carryforwards	385,800	184,900
Uncertain tax positions	256,000	39,500
Foreign | Research and Development
Income Taxes [Line Items]
Net operating loss carryforwards	$ 5,500	$ 4,900
Netherlands
Income Taxes [Line Items]
Income tax expense (benefit)			$ (15,900)