Employee Retirement Plans (Details 4)	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
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	53.50%	49.40%
Target Asset Allocation	52.50%
Permitted Range - Minimum	40.00%
Permitted Range - Maximum	65.00%
Pension Benefit [Member] | Equity Securities International [Member]
Pension Plan
Actual Pension Plan	10.50%	10.70%
Target Asset Allocation	12.50%
Permitted Range - Minimum	7.50%
Permitted Range - Maximum	17.50%
Pension Benefit [Member] | Equity Securities [Member]
Pension Plan
Actual Pension Plan	64.00%	60.10%
Target Asset Allocation	65.00%
Permitted Range - Minimum	60.00%
Permitted Range - Maximum	70.00%
Pension Benefit [Member] | Fixed Income Funds And Cash Equivalents [Member]
Pension Plan
Actual Pension Plan	36.00%	39.90%
Target Asset Allocation	35.00%
Permitted Range - Minimum	30.00%
Permitted Range - Maximum	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	68.50%	62.20%
Target Asset Allocation	65.00%
Permitted Range - Minimum	60.00%
Permitted Range - Maximum	70.00%
VEBA Trust [Member] | Fixed Income Funds And Cash Equivalents [Member]
Pension Plan
Actual Pension Plan	31.50%	37.80%
Target Asset Allocation	35.00%
Permitted Range - Minimum	30.00%
Permitted Range - Maximum	40.00%