Income Taxes Rate Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Tax at statutory rate of 35%	$ 192,667	$ 178,768	$ 166,887
Common stock dividends deductible for tax reporting	(2,570)	(2,413)	(2,307)
State taxes (net of federal benefit)	11,504	12,869	11,636
Change in valuation allowance	1,324	4,998	6,969
Other, net	(2,552)	1,468	3,817
Income tax expense (benefit)	$ 200,373	$ 195,690	$ 187,002