Note 4 - Restricted Cash (Details Textual) - USD ($) $ in Millions |
Sep. 30, 2018 |
Jun. 30, 2018 |
|---|---|---|
| Letters of Credit Outstanding, Amount | $ 6.2 | $ 6.2 |
| Letter of Credit Issued for Workers Compensation Obligation [Member] | ||
| Letters of Credit Outstanding, Amount | $ 5.9 |