Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Net income	$ 36,812	$ 32,668
Net gains (losses) in fair value of derivative instruments (net of tax $(1,799) and $1,267, respectively)	2,537	(1,801)
Reclassifications of net losses on derivative instruments (net of tax of $(84) and $(121), respectively)	119	170
Benefit plans (net of tax of $(139) and $(99),respectively)	195	139
Other comprehensive income (loss)	2,851	(1,492)
Comprehensive income	$ 39,663	$ 31,176