Condensed Consolidated Statement Of Changes In Shareholders' Equity (USD $) In Thousands	Common Stock [Member]	Paid-in Capital [Member]	Retained Earnings [Member]	Total
Beginning Balance at Sep. 30, 2010	$ 64,443	$ 133,095	$ 1,172,596	$ 1,370,134
Beginning Balance (in shares) at Sep. 30, 2010	64,443
Net income			198,747	198,747
Vesting of restricted stock awards	99	(99)
Vesting of restricted stock awards (in shares)	99
Exercise of employee stock options	304	4,093		4,397
Exercise of employee stock options (in shares)	304
Stock option and restricted stock award compensation expense		5,406		5,406
Ending Balance at Jun. 30, 2011	$ 64,846	$ 142,495	$ 1,371,343	$ 1,578,684
Ending Balance (in shares) at Jun. 30, 2011	64,846