Supplemental Statements of Cash Flows Information (Schedule of Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Supplemental Statements of Cash Flows Information
Interest paid, net of amounts capitalized	$ 32,608	$ 27,922	$ 26,627
Income taxes paid	51,218	66,477	52,355
Income tax refunds received	689	2,303	6,336
Purchases of property, plant and equipment on account	23,966	13,437	5,345
Common shares issued from treasury to settle benefit plan obligations (Note 18)	12,574	11,193	9,780
Notes receivable from municipalities for economic development incentives	0	6,596	8,114
Cashless exercise of stock options	1,532	1,286	2,645
Settlement of receivable through cashless acquisition of treasury shares in connection with the cashless exercise of stock options	$ 1,602	$ 1,736	$ 3,447