Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014	Mar. 31, 2015	Sep. 30, 2013
Income Tax Contingency [Line Items]
Effective tax rate	13.00%	59.00%	36.00%
Release of a FIN 48 reserve related to the federal research and development tax credit	$ 1,046	$ 784	$ 4,026	$ 4,100	$ 3,845
Retroactive tax benefit	800	600
Undistributed earnings of foreign subsidiaries	21,500
Operating loss carryforwards	$ 39,000
Operating loss carryforwards, valuation allowance		$ 9,300
Operating loss carryforwards, expiration period (in years)	20 years
Operating loss carryforwards, expiration date	2031
Tax benefit	$ 4,100
Decrease in unrecognized tax benefits due to expiration of certain federal statutes of limitations	32.00%
Decrease in unrecognized tax benefits due to audit resolution	33.00%
R&D Tax Credit
Income Tax Contingency [Line Items]
Tax credit carryforward description	On December 18, 2015, the “Protecting Americans from Tax Hikes Act of 2015” was enacted which retroactively reinstated and made permanent the R&D Tax Credit