UNAUDITED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016
Current assets
Allowance for doubtful accounts	$ 1,799	$ 1,828
LIABILITIES AND STOCKHOLDERS' EQUITY
Long-term debt, prepaid debt issuance cost	$ 504	$ 696
Stockholders' equity
Common stock: authorized (in shares)	200,000,000	200,000,000
Common stock: par value (in dollars per share)	$ 0.001	$ 0.001
Common stock: issued (in shares)	35,144,183	34,261,304
Treasury stock at cost, shares (in shares)	9,835,419	9,744,642