Stockholders' Equity (Summary of Activity for RSUs) (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares shares in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2024	Mar. 31, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of units, Beginning balance	170	177
Granted, Number of units	155	167
Released, Number of units	(5)	(24)
Forfeited, Number of units	(1)	(1)
Number of units, Ending balance	319	319
Weighted-Average Grant Date Fair Value, Beginning balance	$ 96.95	$ 93.46
Granted, Weighted-Average Grant Date Fair Value	137.76	137.33
Released, Weighted-Average Grant Date Fair Value	89.03	86.59
Forfeited, Weighted-Average Grant Date Fair Value	111.78	108.48
Weighted-Average Grant Date Fair Value, Ending balance	$ 116.9	$ 116.9