Debt and Other Obligations - Schedule of Long-Term Obligations (Parenthetical) (Detail)	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Revolving Credit Facility Expiry October 2022 [Member]
Debt Instrument [Line Items]
Debt instrument due, year	2022	2022
2.55% Notes Due 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	2.55%	2.55%
Debt instrument due, year	2018	2018
3.7% Notes Due 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	3.70%	3.70%
Debt instrument due, year	2022	2022
3.4% Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	3.40%	3.40%
Debt instrument due, year	2026	2026
Notes Due 2019, 7.42% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	7.42%	7.42%
Debt instrument due, year	2019	2019
Notes Due 2022, 8.34% - 8.47% [Member]
Debt Instrument [Line Items]
Debt instrument due, year	2022	2022
Notes Due 2022, 8.34% - 8.47% [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	8.34%	8.34%
Notes Due 2022, 8.34% - 8.47% [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	8.47%	8.47%
Notes Due 2028, 6.57%-7.28% [Member]
Debt Instrument [Line Items]
Debt instrument due, year	2028	2028
Notes Due 2028, 6.57%-7.28% [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	6.57%	6.57%
Notes Due 2028, 6.57%-7.28% [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	7.28%	7.28%
Chinese Renminbi Debt, Due 2018, 4.75% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.75%	4.75%
Debt instrument due, year	2018	2018
Capital Lease Obligations, Due Through 2033 [Member]
Debt Instrument [Line Items]
Debt instrument maturity, maximum range	2033	2033