Benefit Plans (Details) (USD $) In Thousands	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Pension Plans [Member]
Net pension and postretirement cost
Service cost	$ 88,692	$ 72,901	$ 55,004
Interest cost	93,228	90,432	87,480
Expected return on plan assets	(103,081)	(99,199)	(86,819)
Amortization of prior service (credit) cost	(1,294)	(1,091)	(1,099)
Amortization of loss (gain)	55,735	41,812	17,235
Amortization of net asset	(34)	(47)	(59)
Curtailment/Settlement loss	1,096
Net pension and postretirement cost	134,342	104,808	71,742
Other Postretirement Benefit [Member]
Net pension and postretirement cost
Service cost	5,842	5,007	3,441
Interest cost	13,143	14,190	15,338
Amortization of prior service (credit) cost	(686)	4	(463)
Amortization of loss (gain)	4,465	3,408	(143)
Net pension and postretirement cost	$ 22,764	$ 22,609	$ 18,173