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, 2024	Dec. 31, 2023	Sep. 30, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, Number of options	4,213	4,611	4,842
Options vested and exercisable, Number of options	3,287
Options vested and expected to vest, Number of options	4,177
Options outstanding, Weighted-Average Exercise Price	$ 83.54	$ 80.99	$ 80.48
Options vested and exercisable, Weighted-Average Exercise Price Per Share	79.53
Options vested and expected to vest, Weighted-Average Exercise Price Per Share	$ 83.37
Options outstanding, Weighted-Average Remaining Life in Years	5 years 6 months
Options vested and exercisable, Weighted-Average Remaining Life in Years	4 years 9 months 18 days
Options vested and expected to vest, Weighted-Average Remaining Life in Years	5 years 6 months
Options outstanding, Aggregate Intrinsic Value	$ 297,376
Options vested and exercisable, Aggregate Intrinsic Value	245,191
Options vested and expected to vest, Aggregate Intrinsic Value	$ 295,556