Stockholders' Equity (Stock Options Vested, or Expected to Vest and Exercisable) (Details) - Stock Options [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options outstanding, Number of options	5,407	5,517	5,443
Options vested and exercisable, Number of options	3,332
Options vested and expected to vest, Number of options	5,333
Options outstanding, Weighted-Average Exercise Price	$ 67.91	$ 67.50	$ 62.00
Options vested and exercisable, Weighted-Average Exercise Price Per Share	58.52
Options vested and expected to vest, Weighted-Average Exercise Price Per Share	$ 67.72
Options outstanding, Weighted-Average Remaining Life in Years	6 years 2 months 12 days
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 2 months 12 days
Options outstanding, Aggregate Intrinsic Value	$ 297,257
Options vested and exercisable, Aggregate Intrinsic Value	214,452
Options vested and expected to vest, Aggregate Intrinsic Value	$ 294,203