Employee Retirement Plans (Details 4)	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Pension Benefit [Member]
Pension Plan
Actual Pension Plan	100.00%	100.00%
Target Asset Allocation	100.00%
Pension Benefit [Member] | Equity Securities Domestic [Member]
Pension Plan
Actual Pension Plan	49.40%	56.10%
Target Asset Allocation	52.50%
Minimum Range	40.00%
Maximum Range	65.00%
Pension Benefit [Member] | Equity Securities International [Member]
Pension Plan
Actual Pension Plan	10.70%	12.20%
Target Asset Allocation	12.50%
Minimum Range	7.50%
Maximum Range	17.50%
Pension Benefit [Member] | Fixed Income Funds And Cash Equivalents [Member]
Pension Plan
Actual Pension Plan	39.90%	31.70%
Target Asset Allocation	35.00%
Minimum Range	30.00%
Maximum Range	40.00%
VEBA Trust [Member]
Pension Plan
Actual Pension Plan	100.00%	100.00%
Target Asset Allocation	100.00%
VEBA Trust [Member] | Equity Securities Domestic [Member]
Pension Plan
Actual Pension Plan	62.20%	65.00%
Target Asset Allocation	65.00%
Minimum Range	60.00%
Maximum Range	70.00%
VEBA Trust [Member] | Fixed Income Funds And Cash Equivalents [Member]
Pension Plan
Actual Pension Plan	37.80%	35.00%
Target Asset Allocation	35.00%
Minimum Range	30.00%
Maximum Range	40.00%
Equity Securities [Member]
Pension Plan
Actual Pension Plan	60.10%	68.30%
Target Asset Allocation	65.00%
Minimum Range	60.00%
Maximum Range	70.00%