Note 3 - Investments

12 Months Ended

Dec. 31, 2017

Notes to Financial Statements

Cash and Cash Equivalents Disclosure [Text Block]

3.

Investments

All of the Company’s investments are classified as available-for-sale and 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 deposits of

$24.0

million and

$20.5

million at

December 31, 2017

and

2016,

respectively. There were

no

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

December 31, 2017

or

2016.