Note 4 - Investments

6 Months Ended

Jun. 30, 2018

Notes to Financial Statements

Cash and Cash Equivalents Disclosure [Text Block]

4. Investments

All of the Company’s investments are carried at fair value with unrealized gains and losses recorded as a component of accumulated other comprehensive income, net of related income taxes. The Company held bank certificates of deposit of

$13.3

million and

$24.0

million as of

June 30, 2018

and

December 31, 2017,

respectively. There were

no

unrealized gains or losses on the Company’s available-for-sale securities as of

June 30, 2018

or

December 31, 2017.