Income Taxes - Schedule Of Provision For Income Taxes (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Current, U.S. federal									$ 26,978	$ 43,039	$ 78,454
Current, State									4,230	13,864	9,800
Current, Foreign									50,368	49,197	41,040
Total									81,576	106,100	129,294
Deferred, U.S. federal									10,875	8,716	21,259
Deferred, State									(1,121)	1,617	725
Deferred, Foreign									(2,374)	(3,056)	(1,207)
Total									7,380	7,277	20,777
Income taxes (benefit)	$ 19,860	$ 17,890	$ 22,178	$ 29,028	$ 23,274	$ 21,557	$ 34,140	$ 34,406	$ 88,956	$ 113,377	$ 150,071