Note 4 - Investments

3 Months Ended

Mar. 31, 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 (loss), net of related income taxes. The Company held bank certificates of deposit of

$21.3

million and

$24.0

million at

March 31, 2018

and

December 31, 2017,

respectively. There were

no

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

March 31, 2018

or

December 31, 2017.