|
Note 3 - Investments (Details) - Summary of Investments by Investment (USD $)
In Thousands, unless otherwise specified
|
12 Months Ended |
|
Dec. 31, 2014
|
Dec. 31, 2013
|
| Available-for-sale securities: |
|
|
| US treasury securities,Cost |
$ 38,873 |
$ 90,723 |
| US treasury securities, Gross Unrealized Gain |
76 |
223 |
| US treasury securities, Gross Unrealized Loss |
(41) |
(56) |
| US treasury securities, Fair Value |
38,908 |
90,890 |
| US Treasury Securities [Member] |
|
|
| Available-for-sale securities: |
|
|
| US treasury securities,Cost |
2,056 |
25,061 |
| US treasury securities, Gross Unrealized Gain |
1 |
11 |
| US treasury securities, Fair Value |
2,057 |
25,072 |
| US States and Political Subdivisions Debt Securities [Member] |
|
|
| Available-for-sale securities: |
|
|
| US treasury securities,Cost |
19,686 |
34,912 |
| US treasury securities, Gross Unrealized Gain |
43 |
105 |
| US treasury securities, Gross Unrealized Loss |
(17) |
(34) |
| US treasury securities, Fair Value |
19,712 |
34,983 |
| Corporate Debt Securities [Member] |
|
|
| Available-for-sale securities: |
|
|
| US treasury securities,Cost |
16,381 |
28,565 |
| US treasury securities, Gross Unrealized Gain |
32 |
105 |
| US treasury securities, Gross Unrealized Loss |
(21) |
(22) |
| US treasury securities, Fair Value |
16,392 |
28,648 |
| Asset-backed Securities [Member] |
|
|
| Available-for-sale securities: |
|
|
| US treasury securities,Cost |
750 |
685 |
| US treasury securities, Gross Unrealized Gain |
|
1 |
| US treasury securities, Gross Unrealized Loss |
(3) |
|
| US treasury securities, Fair Value |
747 |
686 |
| Certificates of Deposit [Member] |
|
|
| Available-for-sale securities: |
|
|
| US treasury securities,Cost |
|
1,500 |
| US treasury securities, Gross Unrealized Gain |
|
1 |
| US treasury securities, Fair Value |
|
$ 1,501 |