Restructuring and Other Charges, Net - Additional Information (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Current Fiscal Year End Date	--09-30
Restructuring and other charges, net	$ (23,302)	$ (35,408)	$ (18,901)
Restructuring Reserve	$ 7,605	$ 17,057	$ 9,743	$ 12,474
Number of personnel eliminated	391	1,318	792
Proceeds from Insurance Claims	$ 500
Tangible Asset Impairment Charges		$ 7,100	$ 10,800
Restructuring and other charges, net	80,465	57,026	59,923
Personnel
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	(19,371)	(31,520)	(12,553)
Restructuring and Related Cost, Incurred Cost	19,371	31,520	12,553
Restructuring Reserve	3,956	10,556	1,474	2,599
Facilities
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	(3,931)	(3,888)	(6,348)
Restructuring and Related Cost, Incurred Cost	3,931	3,888	6,348
Restructuring Reserve	3,649	6,501	8,269	$ 9,875
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	57,163	21,618	41,022
Other Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net		(8,800)
Other Restructuring Costs		4,800	18,100
Malware Incident - Professional Service Charges [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs		4,000	4,000
Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring and other charges, net	(3,803)	(11,060)	(3,350)
Corporate | Personnel
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	3,039	10,107	1,337
Corporate | Facilities
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Incurred Cost	764	953	2,013
Corporate | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	9,404	14,515	21,491
Chief Executive Officer [Member] | Corporate | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs		$ 5,700	$ 8,100
Stand-up and separation [Member] | Corporate | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	45,600
Accelerated depreciation [Member] | Corporate | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Other Restructuring Costs	$ 3,300