Stockholders' Equity (Stock Options Vested, or Expected to Vest and Exercisable) (Details) - Stock Options [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, Number of options	5,352	5,711	5,339
Options vested and exercisable, Number of options	3,586
Options vested and expected to vest, Number of options	5,285
Options outstanding, Weighted-Average Exercise Price	$ 73.71	$ 72.10	$ 68.21
Options vested and exercisable, Weighted-Average Exercise Price Per Share	65.34
Options vested and expected to vest, Weighted-Average Exercise Price Per Share	$ 73.43
Options outstanding, Weighted-Average Remaining Life in Years	6 years
Options vested and exercisable, Weighted-Average Remaining Life in Years	4 years 10 months 24 days
Options vested and expected to vest, Weighted-Average Remaining Life in Years	6 years
Options outstanding, Aggregate Intrinsic Value	$ 274,035
Options vested and exercisable, Aggregate Intrinsic Value	213,593
Options vested and expected to vest, Aggregate Intrinsic Value	$ 272,080