Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Dec. 31, 2017	Sep. 30, 2017
Current assets:
Allowance, accounts receivable	$ 3,793	$ 3,776
Stockholders' equity:
Preferred stock, par value	$ 0.003	$ 0.003
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.001455	$ 0.001455
Common stock, shares authorized	150,000	150,000
Common stock, shares issued	72,960	72,960
Treasury stock, shares	11,706	11,739
Treasury stock held for deferred compensation, shares	200	186