| Note 9 - Income Taxes | 6 Months Ended | 
|---|---|
| Mar. 31, 2017 | |
| Notes to Financial Statements | |
| Income Tax Disclosure [Text Block] | Note  9.Income Taxes For the  threeand sixmonths ended  March 31, 2017,the Company recorded a provision for income taxes of $433,000and $800,000,respectively, reflecting an effective tax rate of 32.3%and 31.0%,respectively. The primary difference between the effective tax rate and the statutory tax rate is related to nondeductible meals and entertainment, favorable domestic manufacturing deduction and research and development credits, expenses related to equity award compensation and favorable discrete items for the threeand sixmonths ended  March 31, 2017from tax benefits related to stock-based compensation awards. As of both   March 31, 2017and  September 30, 2016,the Company had a remaining valuation allowance of approximately $322,000  March 31, 2017. For the  threeand sixmonths ended  March 31, 2016,the Company recorded a provision for income taxes of $690,000and $1,216,000,respectively, reflecting an effective tax rate of 31.6%and 29.0%,respectively. The primary difference between the effective tax rate and the statutory tax rate is related to nondeductible meals and entertainment, expenses related to equity award compensation and favorable discrete items for the threeand sixmonths ended  March 31, 2016from tax benefits related to stock-based compensation awards and research and development credits which were permanently extended in  December 2015by the federal government. Deferred taxes recognize the impact of temporary differences between the amounts of the assets and liabilities recorded for financial statement purposes and these amounts measured in accordance with tax laws. The Company’s realization of deferred tax temporary differences is contingent upon future taxable earnings. The Company reviewed its deferred tax assets for expected utilization using a “more likely than not” criteria by assessing the available positive and negative factors surrounding its recoverability. As of d tax benefits as a component of income tax expense. The Company does not expect any material changes in its unrecognized tax positions over the next  March 31, 2017,we do nothave any unrecognized tax benefits. It is the Company’s practice to recognize interest and penalties accrued on any unrecognize 12months. |