Debt and Other Obligations - Schedule of Long-Term Obligations (Parenthetical) (Detail)	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Revolving Credit Facility, expires fiscal 2023 [Member]
Debt Instrument [Line Items]
Debt instrument due, year	2023	2023
Revolving Credit Facility - Canada, expires fiscal 2021 [Member]
Debt Instrument [Line Items]
Debt instrument due, year	2021	2021
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 fiscal 2022 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	3.70%	3.70%
Debt instrument due, year	2022	2022
3.4% Notes due fiscal 2026 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	3.40%	3.40%
Debt instrument due, year	2026	2026
Notes due fiscal 2019, 7.42% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	7.42%	7.42%
Debt instrument due, year	2019	2019
Notes due fiscal 2022, 8.34% - 8.47% [Member]
Debt Instrument [Line Items]
Debt instrument due, year	2022	2022
Notes due fiscal 2022, 8.34% - 8.47% [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	8.34%	8.34%
Notes due fiscal 2022, 8.34% - 8.47% [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	8.47%	8.47%
Notes due fiscal 2028, 6.57% - 7.28% [Member]
Debt Instrument [Line Items]
Debt instrument due, year	2028	2028
Notes due fiscal 2028, 6.57% - 7.28% [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	6.57%	6.57%
Notes due fiscal 2028, 6.57% - 7.28% [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	7.28%	7.28%
Chinese Renminbi Debt, Due Fiscal 2019, 4.35% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.35%	4.35%
Debt instrument due, year	2019	2019
Chinese Renminbi Debt, Due Fiscal 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