Employee Benefit Plans Employee Benefit Plans - Employee Stock Purchase Plan, Incentive Bonus Plan and Stock-Based Compensation (Details) - USD ($)	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discounted Price For Purchasing Company's Common Stock	85.00%
Employee Stock Purchase Plan, Maximum Percent of Annual Compensation	15.00%
Fair Market Value Of Common Stock Available For Purchase To Eligible Employees Maximum	$ 25,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans	89,652	82,446	77,216
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 2,200,000	$ 1,700,000	$ 1,400,000
Officers' Compensation	$ 14,200,000	$ 11,800,000	$ 11,800,000
Shares available for grant	22,300,000
Employee Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance, shares	3,300,000
Stock Compensation Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance, shares	37,100,000
Increase in common stock reserved for issuance, shares		25,000,000