Stockholders' Equity (Stock Options Vested, or Expected to Vest and Exercisable) (Details) - Stock Options [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2020	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, Number of options	5,901	5,443
Options vested and exercisable, Number of options	3,731
Options vested and expected to vest, Number of options	5,797
Options outstanding, Weighted-Average Exercise Price	$ 65.47	$ 62.00
Options vested and exercisable, Weighted-Average Exercise Price Per Share	55.73
Options vested and expected to vest, Weighted-Average Exercise Price Per Share	$ 65.20
Options outstanding, Weighted-Average Remaining Life in Years	6 years 4 months 24 days
Options vested and exercisable, Weighted-Average Remaining Life in Years	5 years
Options vested and expected to vest, Weighted-Average Remaining Life in Years	6 years 3 months 18 days
Options outstanding, Aggregate Intrinsic Value	$ 330,818
Options vested and exercisable, Aggregate Intrinsic Value	245,492
Options vested and expected to vest, Aggregate Intrinsic Value	$ 326,577