Note 11 - Financial Instruments - Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Jun. 30, 2017 |
|---|---|---|
| Available-for-sale Securities | $ 0 | $ 0 |
| Fair Value, Measurements, Recurring [Member] | ||
| Available-for-sale Securities | ||
| Total | 49,050 | 65,031 |
| Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member] | ||
| Cash equivalents | 49,050 | 65,031 |
| Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | ||
| Available-for-sale Securities | ||
| Total | 49,050 | 65,031 |
| Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member] | ||
| Cash equivalents | 49,050 | 65,031 |
| Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | ||
| Available-for-sale Securities | ||
| Total | ||
| Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member] | ||
| Cash equivalents |