Condensed Consolidated Statements of Stockholders' Equity (Unaudited) Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands		Total		Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings		Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment from adoption of ASU 2016-09 | ASU 2016-09		$ 19				$ 52	$ (33)
Beginning balance (in shares) at Sep. 30, 2017				33,008	6,437
Beginning balance at Sep. 30, 2017		319,029	[1]	$ 330	$ (54,533)	245,528	150,363	[1]	$ (22,659)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	[1]	(4,613)					(4,613)
Other comprehensive income (loss)		2,049	[1]						2,049
Employee stock purchase issuances (in shares)					(74)
Employee stock purchase issuances		618			$ 631	(13)
Repurchase of common stock (in shares)					68
Repurchase of common stock		(681)			$ (681)
Issuance of stock under stock award plans (in shares)				573
Issuance of stock under stock award plans		3,427		$ 6		3,421
Stock-based compensation expense		2,378				2,378
Ending balance (in shares) at Mar. 31, 2018				33,581	6,431
Ending balance at Mar. 31, 2018		322,226	[1]	$ 336	$ (54,583)	251,366	145,717	[1]	(20,610)
Beginning balance (in shares) at Sep. 30, 2018				33,813	6,385
Beginning balance at Sep. 30, 2018		330,493	[1]	$ 338	$ (54,216)	255,936	151,961	[1]	(23,526)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)		6,024					6,024
Other comprehensive income (loss)		(1,642)							(1,642)
Employee stock purchase issuances (in shares)					(63)
Employee stock purchase issuances		549			$ 544	5
Repurchase of common stock (in shares)					91
Repurchase of common stock		(1,044)			$ (1,044)
Issuance of stock under stock award plans (in shares)				658
Issuance of stock under stock award plans		3,751		$ 7		3,744
Stock-based compensation expense		2,707				2,707
Ending balance (in shares) at Mar. 31, 2019				34,471	6,413
Ending balance at Mar. 31, 2019		$ 340,838		$ 345	$ (54,716)	$ 262,392	$ 157,985		$ (25,168)

[1] Prior period information has been restated for the adoption of ASU No. 2014-09, “Revenue from Contracts with Customers (Topic 606),” which we adopted on October 1, 2018.