Long-term Debt (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Debt Covenant, Leverage Ratio, Maximum		3.5 to 1.0
Debt financing costs		$ 2,359	$ 1,297	$ 1,651
Amortization of debt financing costs recognized as interest expense		1,114	1,014	$ 1,045
Balance of unamortized debt issuance costs		5,521	4,276
Line of Credit Facility, Maximum Borrowing Capacity		1,048,808
Outstanding borrowings		352,430
The Notes [Member]
Debt Covenant, Minimum Consolidated Net Worth Calculation, Base Value		$ 800,000
Debt Covenant, Minimum Consolidated Net Worth Calculation, Percentage of Net Income		50.00%
Debt Covenant, Calculations, Period Of Time		rolling four quarter basis
Cross default provisions related to the Company’s other outstanding debt arrangements in excess of this amount, the occurrence of which would permit the lenders to accelerate the amounts due thereunder		$ 60,000
Debt Covenant, Leverage Ratio During Material Acquisition Period, Maximum		4.0 to 1.0
Debt Covenant, Maximum Percentage of Priority Debt To Consolidated Net Worth		25.00%
Prepayment, Maximum Percentage of Principal		100.00%
Prepayment, Partial Payment Minimum		$ 1,000
Non Floating Rate Notes [Member]
Prepayment, Make-Whole Amount Computation, Discount Rate Basis Points		50
Debt Instrument Prepayment Make Whole Amount Computation		computed by discounting the remaining scheduled payments of interest and principal of the Notes being prepaid at a discount rate equal to the sum of 50 basis points and the yield to maturity of U.S. Treasury securities having a maturity equal to the remaining average life of the Notes being prepaid
2008 Note Purchase Agreement [Member]
Issuance Date		Oct. 01, 2008
2009 Note Purchase Agreement [Member]
Issuance Date		Apr. 01, 2009
2013 Note Purchase Agreement [Member]
Issuance Date		Oct. 01, 2013
Face Amount		$ 250,000
Debt financing costs	$ 1,297
Floating Rate Notes [Member]
Debt Instrument Prepayment Make Whole Amount Computation		is computed as a percentage of the principal amount of such floating rate Notes equal to (a) 2%, on or prior to November 15, 2014, (b) 1%, after November 15, 2014 and on or prior to November 15, 2015, and (c) 0% after November 15, 2015.
Series J Notes [Member]
Variable interest rate		1.58%
First Closing Notes [Member]
Issuance Date		Oct. 01, 2013
Second Closing Notes [Member]
Issuance Date		Nov. 15, 2013
Other Foreign Short-term Borrowings [Member]
Outstanding borrowings		$ 0
Foreign Performance Guarantee Facilities [Member]
Line of Credit Facility, Maximum Borrowing Capacity		8,619
Outstanding borrowings		0
Foreign Lines of Credit And Overdraft Facilities [Member]
Line of Credit Facility, Maximum Borrowing Capacity		40,189
Outstanding borrowings		2,430
Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity		1,000,000
Outstanding borrowings		$ 350,000
Revolving Credit Facility [Member] | Minimum [Member]
Basis Spread On Variable Rate		0.85%
Chinese Credit Facility [Member]
Line of Credit Facility, Expiration Date		Sep. 01, 2016
Line of Credit Facility, Maximum Borrowing Capacity		$ 22,700	22,700
Outstanding borrowings		$ 0
Chinese Credit Facility, RMB Denominated Loan [Member]
Variable Rate Basis		interest at the prevailing interest rate offered by the People's Bank of China on the date of borrowing, plus a margin equal to 15% of that prevailing rate
Chinese Credit Facility, USD Denominated Loan [Member]
Variable Rate Basis		interest at the lender's cost of borrowing rate at the date of borrowing, plus 3%
Revolving Credit Agreement [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 600,000
Outstanding borrowings			$ 210,000
Credit facility effective interest rate on outstanding borrowing			1.21%
Amended Revolving Credit Agreement [Member]
Debt Covenant, Leverage Ratio, Maximum		3.5 to 1.0
Debt Covenant, Minimum Consolidated Net Worth Calculation, Base Value		$ 800,000
Debt Covenant, Minimum Consolidated Net Worth Calculation, Percentage of Net Income		50.00%
Debt Covenant, Minimum Consolidated Net Worth Calculation, Percentage of Net Proceeds of Issuance of Capital Stock		50.00%
Debt Covenant, Leverage Ratio During Material Acquisition Period, Maximum		4.0 to 1.0
Line of Credit Facility, Initiation Date		Apr. 28, 2015
Line of Credit Facility, Expiration Date		Apr. 28, 2020
Line of Credit Facility, Maximum Borrowing Capacity		$ 1,000,000
Outstanding borrowings		$ 350,000
Credit facility effective interest rate on outstanding borrowing		1.44%
Amended Revolving Credit Agreement [Member] | Minimum [Member]
Basis Spread On Variable Rate		0.85%
Amended Revolving Credit Agreement [Member] | Maximum [Member]
Basis Spread On Variable Rate		1.65%