Retirement and Post-Retirement Employee Benefit Plans Fair Value of Plan Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Pension Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 280,204	$ 301,708
Actual return on plan assets	48,656	5,154
Employer contributions	46,534	876
Benefits paid	(24,553)	(27,534)
Divestitures	(7,697)	0
Fair value of plan assets at end of year	343,144	280,204
Other Postretirement Benefit Plans Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	53,065	53,033
Actual return on plan assets	12,912	(1,500)
Employer contributions	22,139	11,254
Plan participants' contributions	3,649	2,892
Benefits paid	(13,197)	(13,046)
Subsidy Payments	0	432
Divestitures	(1,496)	0
Fair value of plan assets at end of year	77,072	53,065
Supplemental Executive Retirement Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	0	0
Employer contributions	4,638	7,537
Benefits paid	(4,638)	(7,537)
Fair value of plan assets at end of year	$ 0	$ 0