Restructuring - Summary of Restructuring Costs (Detail) $ in Thousands	9 Months Ended
	Jun. 30, 2020 USD ($)
Restructuring Cost and Reserve [Line Items]
Balance at September 30, 2019	$ 1,136
Restructuring charges	661
Reversal of prior period accruals	(41)
Payments	(1,727)
Balance at June 30, 2020	29
Employee Separation and Related Costs [Member]
Restructuring Cost and Reserve [Line Items]
Balance at September 30, 2019	1,010
Restructuring charges	575
Reversal of prior period accruals	(41)
Payments	(1,515)
Balance at June 30, 2020	29
Lease and Other Contract Termination Fees [Member]
Restructuring Cost and Reserve [Line Items]
Balance at September 30, 2019	12
Restructuring charges	86
Payments	(98)
Other [Member]
Restructuring Cost and Reserve [Line Items]
Balance at September 30, 2019	114
Payments	$ (114)