Employee Retirement Plans - Actuarial Assumptions for Domestic Plans (Details)	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Pension Benefit
Weighted-average assumption:
Discount rate - benefit obligations	4.60%	4.60%	5.20%
Discount rate - benefit cost	4.60%	5.20%	4.20%
Expected return on plan assets	7.75%	7.75%	7.75%
Rate of increase in salary levels	3.25%	3.25%	3.25%
Other Postretirement Benefits
Weighted-average assumption:
Discount rate - benefit obligations	4.70%	4.60%
Discount rate - benefit cost	4.60%
Expected return on plan assets	5.00%	5.00%	5.00%
Rate of increase in salary levels	3.25%	3.25%	3.25%
Other Postretirement Benefits | Minimum
Weighted-average assumption:
Discount rate - benefit obligations		5.10%
Discount rate - benefit cost	5.10%	4.10%
Other Postretirement Benefits | Maximum
Weighted-average assumption:
Discount rate - benefit obligations		5.40%
Discount rate - benefit cost	5.40%	4.30%