Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Sep. 30, 2016
Statement Of Financial Position [Abstract]
Property and equipment, accumulated depreciation	$ 64,930	$ 61,003
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	40,000,000	40,000,000
Common stock, shares issued	26,083,154	25,977,632
Common stock, shares outstanding	24,243,083	24,285,616
Treasury stock, shares	1,840,071	1,692,016

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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