Leases - Schedule of Weighted Average Remaining Term and Discount Rates (Detail)	Sep. 30, 2020	Sep. 30, 2019
Leases [Abstract]
Operating leases, Weighted average remaining lease term (years)	6 years 1 month 17 days	6 years 2 months 8 days
Finance leases, Weighted average remaining lease term (years)	2 years 5 months 12 days	1 year 8 months 8 days
Operating leases, Weighted average discount rate	3.43%	3.65%
Finance leases, Weighted average discount rate	3.46%	4.85%