Restructuring Charges (Narrative) (Details)	12 Months Ended			23 Months Ended	30 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($) employee	Sep. 30, 2015 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 2,415,000	$ 6,244,000	$ 36,608,000	$ 6,244,000	$ 6,244,000	$ 15,254,000
Restructuring charges (credit)	(1,003,000)	7,942,000	76,273,000
Payments for Restructuring	2,756,000	37,074,000	55,019,000
Old headquarters annual charge	12,000,000
Headquarters relocation charges	4,800,000
Employee Severance And Related Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	0	1,736,000	35,177,000	1,736,000	1,736,000	14,086,000
Restructuring charges (credit)	(509,000)	2,373,000	74,929,000
Payments for Restructuring	1,247,000	35,069,000	53,966,000
Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2,415,000	4,508,000	1,431,000	4,508,000	4,508,000	$ 1,168,000
Restructuring charges (credit)	(494,000)	5,569,000	1,344,000
Payments for Restructuring	1,509,000	2,005,000	1,053,000
Restructuring Plan 2016
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2,400,000
Restructuring charges (credit)	(200,000)	8,200,000	77,100,000	$ 84,500,000
Payments for Restructuring	2,600,000	36,400,000	42,100,000
Number of Employees Terminated				800
Restructuring Plan 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges (credit)	(800,000)	300,000	(800,000)		$ 42,100,000
Payments for Restructuring	200,000	$ 700,000	12,100,000
Restructuring and Related Cost, Number of Positions Eliminated | employee					411
Prior Restructuring Plans [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring			$ 800,000
Other Current Liabilities [Member] | Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	1,500,000
Other Noncurrent Liabilities [Member] | Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	900,000
sublease income [Member] | Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 2,800,000