Long-term Debt (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2014
Debt financing costs	$ 0	$ 1,297
Balance of unamortized debt issuance costs	3,769			4,276
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
Series J Notes [Member]
Variable interest rate	1.51%
First Closing Notes [Member]
Issuance Date	Oct. 01, 2013
Second Closing Notes [Member]
Issuance Date	Nov. 15, 2013
Foreign Lines of Credit And Overdraft Facilities [Member]
Outstanding borrowings	0
Chinese Credit Facility [Member]
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 25% 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]
Variable Rate Basis	LIBOR
Line of Credit Facility, Expiration Date	Jul. 01, 2018
Line of Credit Facility, Maximum Borrowing Capacity	600,000
Outstanding borrowings	$ 213,000			$ 210,000
Credit facility effective interest rate on outstanding borrowing	1.23%			1.21%
Revolving Credit Agreement [Member] | Minimum [Member]
Basis Spread On Variable Rate	0.85%
Revolving Credit Agreement [Member] | Maximum [Member]
Basis Spread On Variable Rate	1.65%