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, 2011	$ 177,013	$ 128	$ 57,382	$ 119,333	$ 170
Beginning Balance, Shares at Sep. 30, 2011		12,702,516
Net income	35,118			35,118
Other comprehensive loss	(395)				(395)
Excess tax benefit from share-based compensation	1,131		1,131
Issuance of restricted stock, Shares	0
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 expense	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
Net income	69,557			69,557
Other comprehensive loss	(839)				(839)
Excess tax benefit from share-based compensation	3,390		3,390
Issuance of restricted stock, Shares	0
Issuance of common stock pursuant to exercise of options, net of tax	1,419	1	1,418
Issuance of common stock pursuant to exercise of options, Shares	139,906	139,906
Stock-based compensation expense	544		544
Ending Balance at Sep. 30, 2013	289,058	129	65,985	224,008	(1,064)
Ending Balance, Shares at Sep. 30, 2013	12,942,066	12,942,066
Net income	36,911			36,911
Other comprehensive loss	(1,432)				(1,432)
Excess tax benefit from share-based compensation	178		178
Issuance of restricted stock		2	(2)
Issuance of restricted stock, Shares	197,000	197,000
Forfeiture of restricted stock	0	0	0	0	0
Forfeiture of restricted stock, Shares		(8,000)
Issuance of common stock pursuant to exercise of options, net of tax	424		424
Issuance of common stock pursuant to exercise of options, Shares	16,350	16,350
Stock-based compensation expense	4,119		4,119
Ending Balance at Sep. 30, 2014	$ 329,258	$ 131	$ 70,704	$ 260,919	$ (2,496)
Ending Balance, Shares at Sep. 30, 2014	13,147,416	13,147,416