Debt and Other Obligations - Schedule of Long-Term Obligations (Parenthetical) (Detail)	1 Months Ended	12 Months Ended
	Jun. 30, 2019	Sep. 30, 2021	Sep. 30, 2020
Revolving Credit Facility Expiry October 2026 [Member]
Debt Instrument [Line Items]
Debt instrument due, year		2026	2026
Revolving Credit Facility - Euro, expires fiscal 2024 [Member]
Debt Instrument [Line Items]
Debt instrument due, year		2024	2024
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
4.0% Notes due 2029 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate	4.00%	4.00%	4.00%
Debt instrument due, year	2029	2029	2029
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, matured fiscal 2022, 4.35% [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate		4.35%	4.35%