Restructuring and Other Charges, net (Additional Information) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring Charges and Other Expenses	$ 6,683	$ 14,641
Document Fiscal Year Focus	2020
Restructuring charges	$ 4,000	6,100
Restructuring and Related Cost, Accelerated Depreciation		2,500
Proceeds from Insurance Claims		1,100
Tangible Asset Impairment Charges	(200)
Personnel
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	1,500		$ 3,587
Restructuring charges	2,913	6,200
Facilities
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	16,700		$ 3,622
Restructuring charges	1,135	(200)
Corporate | Personnel
Restructuring Cost and Reserve [Line Items]
Restructuring charges	333	1,153
Corporate | Facilities
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(532)	(290)
Corporate | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Charges	2,635	6,071
Corporate | Chief Executive Officer [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Charges		$ 7,200
Stand-up and separation [Member] | Corporate | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Charges	$ 2,800