Weighted Average Actuarial Assumptions (Detail)		12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected long-term rate of return on plan assets	[1]	7.00%	7.00%	7.00%
Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected long-term rate of return on plan assets	[1]	4.25%	4.50%	3.92%
Rate of increase in compensation levels for:
Benefit obligation		3.20%	3.20%	3.20%
Net periodic benefit cost		3.20%	3.20%	3.00%
Pension Benefits | U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate for benefit obligation	[2]	4.23%	3.84%	3.62%
Discount rate for net periodic benefit cost		3.84%	3.62%	4.33%
Pension Benefits | Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Discount rate for benefit obligation	[2]	2.90%	2.70%	2.40%
Discount rate for net periodic benefit cost		2.70%	2.40%	3.10%

[1] Primarily based on the targeted allocation, and evaluated for reasonableness by considering such factors as: (i) actual return on plan assets; (ii) historical rates of return on various asset classes in the portfolio; (iii) projections of returns on various asset classes; and (iv) current and prospective capital market conditions and economic forecasts.

[2] Represents a single weighted-average discount rate derived based on a cash flow matching analysis, with the projected benefit payments matching spot rates from a yield curve developed from high-quality corporate bonds.