Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Sep. 30, 2022
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	$ 827,572	$ 1,263,784
Derivative Asset, Statement of Financial Position	Prepaid expenses and other current assets	Prepaid expenses and other current assets
Fair Value, Recurring
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	$ 827,572	$ 1,263,782
Foreign exchange contracts	146	634
Net investment hedge	47,953	124,789
Total Assets	1,318,911	1,764,009
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration liability	18,462
Foreign exchange contracts	276	230
Total Liabilities	18,738	230
Fair Value, Recurring | Cash Equivalents
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	443,240	374,804
Fair Value, Recurring | Fair Value, Inputs, Level 1
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	284,015	651,800
Total Assets	727,255	1,025,855
Fair Value, Recurring | Fair Value, Inputs, Level 1 | Cash Equivalents
Assets, Fair Value Disclosure [Abstract]
Cash equivalents	443,240	374,055
Fair Value, Recurring | Fair Value, Inputs, Level 2
Assets, Fair Value Disclosure [Abstract]
Available-for-sale securities	543,557	611,982
Foreign exchange contracts	146	634
Net investment hedge	47,953	124,789
Total Assets	591,656	738,154
Liabilities, Fair Value Disclosure [Abstract]
Foreign exchange contracts	276	230
Total Liabilities	276	230
Fair Value, Recurring | Fair Value, Inputs, Level 2 | Cash Equivalents
Assets, Fair Value Disclosure [Abstract]
Cash equivalents		$ 749
Fair Value, Recurring | Fair Value, Inputs, Level 3
Liabilities, Fair Value Disclosure [Abstract]
Contingent consideration liability	18,462
Total Liabilities	$ 18,462