Stockholders' Equity (Activity for Stock Option Awards) (Details) - $ / shares shares in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2017	Mar. 31, 2017
Stock-Based Compensation
Number of options, beginning balance	4,792	4,944
Weighted Average Exercise Price Per Share, beginning balance	$ 35.35	$ 35.35
Options granted, Number of options	780	780
Options granted, Weighted Average Exercise Price Per Share	$ 62.64	$ 62.64
Options exercised, Number of options	(236)	(375)
Options exercised, Weighted Average Exercise Price Per Share	$ 33.21	$ 33.81
Options forfeited, Number of options	(5)	(18)
Options forfeited, Weighted Average Exercise Price Per Share	$ 42.73	$ 42.34
Number of options, ending balance	5,331	5,331
Weighted Average Exercise Price Per Share, ending balance	$ 39.43	$ 39.43