Earnings Per Share (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Net Components of Basic and Diluted Earnings per Share
Net income (A)	$ 26,527	$ 19,962	$ 85,794	$ 69,442
Weighted average outstanding shares of common stock (B)	49,926	49,201	49,849	48,969
Dilutive effect of stock options, warrants, and restricted stock	459	439	443	572
Weighted average common stock and common stock equivalents (C)	50,385	49,640	50,292	49,541
Basic earnings per share (A/B)	$ 0.53	$ 0.41	$ 1.72	$ 1.42
Diluted earnings per share (A/C)	$ 0.53	$ 0.40	$ 1.71	$ 1.40
Potential common shares excluded from the calculation of diluted earnings per share	0	5	6	6