Benefit Plans (Details 7) (USD $) In Thousands	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Postemployment benefit costs
Service cost	$ 13,327	$ 11,409	$ 9,944
Interest cost	5,054	4,379	5,435
Amortization of prior service (credit) cost	(1,697)	(1,697)	(1,697)
Amortization of loss	10,490	7,777	4,323
Postemployment benefit costs, Total	$ 27,174	$ 21,868	$ 18,005