Condensed Consolidated Statement Of Changes In Shareholders' Equity (USD $) In Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning Balance at Sep. 30, 2011	$ 1,652,787	$ 64,960	$ 145,084	$ 1,444,270	$ (1,527)
Beginning Balance (in shares) at Sep. 30, 2011		64,960
Net income	176,645
Other comprehensive loss	1,116				1,116
Restricted stock awards		207	(207)
Restricted stock awards (in shares)		207
Exercise of employee stock options	3,262	196	3,066
Exercise of employee stock options (in shares)		196
Stock option and restricted stock award compensation expense	7,709		7,709
Ending Balance at Jun. 30, 2012	$ 1,839,287	$ 65,363	$ 155,652	$ 1,620,915	$ (2,643)
Ending Balance (in shares) at Jun. 30, 2012		65,363