Restructuring Charges (Narrative) (Details)	12 Months Ended			23 Months Ended	30 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($) employee	Sep. 30, 2014 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 6,244,000	$ 36,608,000	$ 15,254,000	$ 6,244,000	$ 6,244,000	$ 26,370,000
Restructuring charges	7,942,000	76,273,000	43,409,000
Employee Severance And Related Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	1,736,000	35,177,000	14,086,000	1,736,000	1,736,000	25,835,000
Restructuring charges	2,373,000	74,929,000	41,997,000
Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	4,508,000	1,431,000	1,168,000	4,508,000	4,508,000	$ 535,000
Restructuring charges	5,569,000	1,344,000	1,412,000
Restructuring Plan 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges	8,100,000			$ 85,300,000
Number of Employees Terminated				800
Restructuring Plan 2016 | Employee Severance And Related Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	2,600,000	75,800,000
Restructuring Plan 2016 | Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	5,600,000	1,300,000
Restructuring Plan 2015
Restructuring Cost and Reserve [Line Items]
Restructuring charges	200,000				$ 42,100,000
Restructuring and Related Cost, Number of Positions Eliminated | employee					411
Restructuring Plan 2015 | Employee Severance And Related Benefits
Restructuring Cost and Reserve [Line Items]
Restructuring charges	200,000	$ 800,000	41,800,000
Restructuring Plan 2015 | Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges			$ 1,400,000
Other Current Liabilities [Member] | Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2,300,000			$ 2,300,000	$ 2,300,000
Other Noncurrent Liabilities [Member] | Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	2,200,000			2,200,000	2,200,000
sublease income [Member] | Facility Closures and Other Costs
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve	$ 4,200,000			$ 4,200,000	$ 4,200,000