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, 2019	Mar. 31, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding, Number of options	5,441	5,733	5,611
Options outstanding, Weighted-Average Exercise Price	$ 53.16	$ 52.27	$ 45.42
Options outstanding, Weighted-Average Remaining Life in Years	6 years
Options outstanding, Aggregate Intrinsic Value	$ 331,053
Options vested and exercisable, Number of options	3,395
Options vested and exercisable, Weighted-Average Exercise Price Per Share	$ 42.12
Options vested and exercisable, Weighted-Average Remaining Life in Years	4 years 8 months 12 days
Options vested and exercisable, Aggregate Intrinsic Value	$ 244,017
Options vested and expected to vest, Number of options	5,336
Options vested and expected to vest, Weighted-Average Exercise Price Per Share	$ 52.70
Options vested and expected to vest, Weighted-Average Remaining Life in Years	6 years
Options vested and expected to vest, Aggregate Intrinsic Value	$ 327,112