Note 4 - Fair Value Measurements - Fair Value of Financial Assets (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Sep. 30, 2017
Current assets:
Cash equivalents	$ 21,331	$ 31,659
Cash surrender value of life insurance policies	9,425	9,026
Total	30,756	40,685
Fair Value, Inputs, Level 1 [Member]
Current assets:
Cash equivalents	21,331	31,659
Cash surrender value of life insurance policies
Total	21,331	31,659
Fair Value, Inputs, Level 2 [Member]
Current assets:
Cash equivalents
Cash surrender value of life insurance policies	9,425	9,026
Total	$ 9,425	$ 9,026