Stockholders' Equity (Activity for Stock Option Awards) (Details) - $ / shares shares in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2018	Mar. 31, 2018
Stock-Based Compensation
Number of options, beginning balance	5,937	5,236
Weighted Average Exercise Price Per Share, beginning balance	$ 44.48	$ 39.58
Options granted, Number of options	6	750
Options granted, Weighted Average Exercise Price Per Share	$ 72.01	$ 78.91
Options exercised, Number of options	(63)	(97)
Options exercised, Weighted Average Exercise Price Per Share	$ 34.54	$ 36.84
Options forfeited, Number of options	0	(9)
Options forfeited, Weighted Average Exercise Price Per Share	$ 0.00	$ 55.61
Number of options, ending balance	5,880	5,880
Weighted Average Exercise Price Per Share, ending balance	$ 44.62	$ 44.62