Acquisitions - Ascatron AB Preliminary Allocation of Purchase Price of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2021	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2019
Assets
Goodwill	$ 1,296,727		$ 1,239,009	$ 319,778
Ascatron AB
Assets
Developed technology	16,378	$ 20,000
Goodwill	21,940	18,922
Other assets	3,194	2,511
Total assets acquired	41,512	41,433
Liabilities
Non-interest bearing liabilities	(1,304)	(203)
Deferred tax liability	(3,504)	(4,526)
Total liabilities assumed	(4,808)	(4,729)
Net assets acquired	36,704	$ 36,704
Assets
Intangibles	(3,622)
Goodwill	3,018
Other assets	683
Total assets acquired	79
Liabilities
Non-interest bearing liabilities	(1,101)
Deferred tax liability	1,022
Total liabilities assumed	(79)
Net assets acquired	$ 0