Consolidated Statement of Stockholders' Equity (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income -Loss
Beginning Balance at Sep. 30, 2009	$ 118,658	$ 120	$ 43,240	$ 75,540	$ (242)
Beginning Balance, Shares at Sep. 30, 2009		11,989,816
Net income	14,082			14,082
Other comprehensive income	86				86
Excess tax benefit from share - based compensation	1,128		1,128
Issuance of common stock pursuant to exercise of options, net of tax	2,187	2	2,185
Issuance of common stock pursuant to exercise of options, Shares	244,900	244,900
Stock-based compensation	445		445
Ending Balance at Sep. 30, 2010	136,586	122	46,998	89,622	(156)
Ending Balance, Shares at Sep. 30, 2010		12,234,716
Net income	29,711			29,711
Other comprehensive income	326				326
Excess tax benefit from share - based compensation	6,896		6,896
Issuance of common stock pursuant to exercise of options, net of tax	2,758	6	2,752
Issuance of common stock pursuant to exercise of options, Shares	467,800	467,800
Stock-based compensation	736		736
Ending Balance at Sep. 30, 2011	177,013	128	57,382	119,333	170
Ending Balance, Shares at Sep. 30, 2011		12,702,516
Net income	35,118			35,118
Other comprehensive income	(395)				(395)
Excess tax benefit from share - based compensation	1,131		1,131
Issuance of common stock pursuant to exercise of options, net of tax	1,358		1,358
Issuance of common stock pursuant to exercise of options, Shares	99,644	99,644
Stock-based compensation	762		762
Ending Balance at Sep. 30, 2012	$ 214,987	$ 128	$ 60,633	$ 154,451	$ (225)
Ending Balance, Shares at Sep. 30, 2012		12,802,160