CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Mar. 31, 2012		Mar. 31, 2011
Net income	$ 54,535		$ 63,927		$ 111,892		$ 88,436
Unrealized gain on available for sale securities, net of tax of $ 575, $(266), $(25) and $(552), respectively	(833)	[1]	390	[1]	36	[1]	800	[1]
Net unrealized (loss) on derivatives, net of tax of $18, $(16), $41 and $(55), respectively	(30)		26		(70)		95
Adjustment to postemployment benefit obligation, net of tax of $(149), $0, $(299) and $0, respectively	219		0		438		0
Other comprehensive income (loss)	(644)		416		404		895
Comprehensive income	$ 53,891		$ 64,343		$ 112,296		$ 89,331

[1] Available for sale securities are included in other noncurrent assets in the Unaudited Condensed Consolidated Balance Sheets.