|
Note 13 - Fair Value Measurements (Details) - Information about Assets and Liabilities Required to be Carried at Fair Value on Recurring Basis (USD $)
In Thousands, unless otherwise specified
|
Dec. 31, 2014
|
Dec. 31, 2013
|
| Investment in marketable securities: |
|
|
| Total fair value of assets |
$ 40,365 |
$ 96,009 |
| Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member] |
|
|
| Cash equivalents: |
|
|
| Cash equivalents |
1,457 |
5,119 |
| Money Market Funds [Member] |
|
|
| Cash equivalents: |
|
|
| Cash equivalents |
1,457 |
5,119 |
| US Treasury Securities [Member] | Fair Value, Inputs, Level 1 [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
2,057 |
25,072 |
| US Treasury Securities [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
2,057 |
25,072 |
| Municipal Bonds [Member] | Fair Value, Inputs, Level 2 [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
19,712 |
34,983 |
| Municipal Bonds [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
19,712 |
34,983 |
| Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
16,392 |
28,648 |
| Corporate Debt Securities [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
16,392 |
28,648 |
| Asset-backed Securities [Member] | Fair Value, Inputs, Level 2 [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
747 |
686 |
| Asset-backed Securities [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
747 |
686 |
| Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
|
1,501 |
| Certificates of Deposit [Member] |
|
|
| Investment in marketable securities: |
|
|
| Investment in marketable securities |
|
1,501 |
| Fair Value, Inputs, Level 1 [Member] |
|
|
| Investment in marketable securities: |
|
|
| Total fair value of assets |
2,057 |
25,072 |
| Fair Value, Inputs, Level 2 [Member] |
|
|
| Investment in marketable securities: |
|
|
| Total fair value of assets |
$ 38,308 |
$ 70,937 |