Note 10 - Share-based Compensation - Restricted Stock Unit Awards, Valuation Assumptions (Details) |
12 Months Ended | ||
|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2016 |
|
| Volatility | 31.50% | 36.80% | 48.10% |
| Risk-free rate of return | 1.76% | 1.03% | 1.93% |
| Dividend yield | 2.47% | 1.96% | 1.95% |
| Expected average life (years) (Year) | 4 years 219 days | 5 years | 6 years 109 days |
| Restricted Stock Units (RSUs) [Member] | |||
| Volatility | 32.90% | 30.80% | |
| Risk-free rate of return | 1.41% | 0.92% | |
| Dividend yield | 2.47% | 1.97% | |
| Expected average life (years) (Year) | 1 year 332 days | 2 years 14 days | |