Benefit Plans - Weighted Average Assumptions Determining Pension Plan (Detail) - Pension Plans	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
U.S. Plans
Net Cost
Discount rate	3.42%	4.15%	4.15%
Expected return on plan assets	7.25%	7.50%	7.50%
Rate of compensation increase	4.25%	4.25%	4.25%
Benefit Obligation
Discount rate	3.72%	3.42%	4.15%
Rate of compensation increase	4.51%	4.25%	4.25%
Foreign Plans
Net Cost
Discount rate	1.70%	2.84%	3.14%
Expected return on plan assets	4.65%	5.02%	5.45%
Rate of compensation increase	2.33%	2.33%	2.49%
Benefit Obligation
Discount rate	2.25%	1.70%	2.84%
Rate of compensation increase	2.30%	2.33%	2.33%