Statement of Shareholders' Equity (USD $) In Thousands	Total	Common Stock Member	Additional Paid In Capital Member	Accumulated Other Comprehensive Income Member	Retained Earnings Member
Balance as of at Sep. 30, 2008	$ 181,003	$ 121	$ 122,319		$ 58,563
Shares Balance as of at Sep. 30, 2008		12,098
Net income	24,905				24,905
Issuance of common stock (shares)		9
Issuance of common stock	240		240
Exercises of common stock options (shares)		81
Exercises of common stock options	143	1	142
Tax benefit of common stock exercises	1,178		1,178
Stock Awards Issued (shares)		8
Issuance of stock awards, net of forfeitures	458		458
Balance as of at Sep. 30, 2009	207,927	122	124,337		83,468
Shares Balance as of at Sep. 30, 2009		12,196
Net income	33,440				33,440
Issuance of common stock (shares)		6
Issuance of common stock	248		248
Exercises of common stock options (shares)		199
Exercises of common stock options	403	2	401
Tax benefit of common stock exercises	3,611		3,611
Stock Awards Issued (shares)		56
Issuance of stock awards, net of forfeitures	1,079	1	1,078
Foreign currency translation	536			536
Other	(457)			(457)
Balance as of at Sep. 30, 2010	246,787	125	129,675	79	116,908
Shares Balance as of at Sep. 30, 2010		12,457
Net income	42,580				42,580
Issuance of common stock (shares)		6
Issuance of common stock	412		412
Exercises of common stock options (shares)		102
Exercises of common stock options	98	1	97
Tax benefit of common stock exercises	2,714		2,714
Stock Awards Issued (shares)		53
Issuance of stock awards, net of forfeitures	861		861
Foreign currency translation	(663)			(663)
Other	21			21
Balance as of at Sep. 30, 2011	$ 292,810	$ 126	$ 133,759	$ (563)	$ 159,488
Shares Balance as of at Sep. 30, 2011		12,618