Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance at Sep. 30, 2011	$ 260,693	$ 291	$ (26,366)	$ 194,580	$ 102,645	$ (10,457)
Beginning balance (in shares) at Sep. 30, 2011		29,101,000	3,472,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	7,615				7,615
Other comprehensive loss	(3,268)					(3,268)
Employee stock purchase issuances (in shares)			(116,000)
Employee stock purchase issuances	1,041		877	164
Issuance of stock upon exercise of stock options (in shares)		168,000
Issuance of stock upon exercise of stock options	1,072	2		1,070
Tax benefit realized upon exercise of stock options	(46)			(46)
Stock-based compensation expense	3,727			3,727
Ending balance at Sep. 30, 2012	270,834	293	(25,489)	199,495	110,260	(13,725)
Ending balance (in shares) at Sep. 30, 2012		29,269,000	3,356,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,805				5,805
Other comprehensive loss	(1,865)					(1,865)
Employee stock purchase issuances (in shares)			(128,000)
Employee stock purchase issuances	1,008		1,030	(22)
Repurchase of common stock (in shares)			1,481,000
Repurchase of common stock	(14,058)		(14,058)
Issuance of stock upon exercise of stock options (in shares)		280,000
Issuance of stock upon exercise of stock options	2,193	3		2,190
Tax benefit realized upon exercise of stock options	(188)			(188)
Acquisition of Etherios, Inc. (in shares)		715,000
Acquisition of Etherios, Inc.	6,741	7		6,734
Stock-based compensation expense	3,773			3,773
Ending balance at Sep. 30, 2013	274,243	303	(38,517)	211,982	116,065	(15,590)
Ending balance (in shares) at Sep. 30, 2013		30,264,000	4,709,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	1,751				1,751
Other comprehensive loss	(2,687)					(2,687)
Employee stock purchase issuances (in shares)			(129,000)
Employee stock purchase issuances	1,009		1,082	(73)
Repurchase of common stock (in shares)	1,734,421		1,734,000
Repurchase of common stock	(15,802)		(15,802)
Issuance of stock under stock award plans (in shares)		440,000
Issuance of stock under stock award plans	3,689	4		3,685
Tax benefit realized upon exercise of stock options	(1,235)			(1,235)
Stock-based compensation expense	4,330			4,330
Ending balance at Sep. 30, 2014	$ 265,298	$ 307	$ (53,237)	$ 218,689	$ 117,816	$ (18,277)
Ending balance (in shares) at Sep. 30, 2014		30,704,000	6,314,000