STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Other Comprehensive Income [Abstract]
Net Income	$ 49,899	$ 53,777	$ 39,725
Net gains (losses) on cash flow hedging derivative instruments:
Net hedging gains arising during the period	297	355	160
Reclassification adjustment for gains included in net income	0	(466)	(264)
Net unrealized (losses) gains on cash flow hedging derivative instruments	297	(111)	(104)
Defined benefit pension and other postretirement benefit plans:
Net acturial (loss) gain arising during the period	(3,397)	339	(1,783)
Amortization of acturial loss included in net periodic pension and other postretirement benefit cost	3,706	426	1,471
Net defined benefit pension and other postretirement benefit plans	309	765	(312)
Other Comprehensive Income (Loss), Before Tax	606	654	(416)
Income Tax Expense (Benefit) Related to Items of Other Comprehensive Income (Loss)	234	252	(160)
Other Comprehensive Income (Loss), Net of Tax	372	402	(256)
Comprehensive Income	$ 50,271	$ 54,179	$ 39,469