Retirement and Post-Retirement Employee Benefit Plans Fair Value of Plan Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	$ 396,887	$ 343,144
Actual return on plan assets	35,289	52,496
Employer contributions	27,110	32,745
Benefits paid	(24,519)	(25,073)
Divestitures	0	(6,425)
Fair value of plan assets at end of year	434,767	396,887
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets at beginning of year	106,413	77,072
Actual return on plan assets	14,003	13,432
Employer contributions	23,550	26,552
Plan participants' contributions	4,435	3,815
Benefits paid	(13,580)	(14,458)
Fair value of plan assets at end of year	134,821	106,413
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	21,902	14,449
Benefits paid	(5,085)	(4,375)
Settlements	(16,817)	(10,074)
Fair value of plan assets at end of year	$ 0	$ 0