Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Income before income taxes:
U.S.	$ 67,968	$ 44,244	$ 12,615
Foreign	9,027	5,154	2,977
Income before income taxes	76,995	49,398	15,592
Current:
U.S. Federal	15,836	5,952	2,722
Foreign	1,712	2,145	678
State	2,079	825	696
Total	19,627	8,922	4,096
Deferred:
U.S. Federal	6,314	7,411	720
Foreign	585	(685)	147
State	601	2,308	1,754
Valuation allowance	(314)	314
Total	7,186	9,348	2,621
Total provision for income taxes	26,813	18,270	6,717
Effective income tax rate reconciliation
Statutory federal tax rate (as a percent)	35.00%	35.00%	35.00%
Tax provision for income taxes at the statutory rate	26,949	17,289	5,457
Foreign tax rate differentials	(864)	(342)	(216)
Provision for state taxes, net of federal taxes	1,578	1,289	468
U.S. tax on distributed and undistributed earnings of foreign subsidiaries	335		165
Manufacturer's deduction	(1,715)	(910)	(193)
Tax credits		(713)	(476)
State tax rate reduction impact on deferred tax asset	89	1,228	1,149
Change in Valuation Allowance	(314)	314
Other, net	755	115	363
Total provision for income taxes	$ 26,813	$ 18,270	$ 6,717