Note 15 - Employee Benefit Plans

12 Months Ended

Dec. 31, 2018

Notes to Financial Statements

Compensation and Employee Benefit Plans, Other than Share-based Compensation [Text Block]

15.

Employee benefit plans

In the United States, the Company has adopted a defined contribution plan (the U.S. Plan) which qualifies under Section 

401

(k) of the Internal Revenue Code. All U.S. employees of the Company who have attained

21

years of age are eligible for participation in the U.S. Plan upon employment. The effective date of the U.S. Plan was

January 

1,

2008.

Under the U.S. Plan, participating employees

may

defer up to the Internal Revenue Service annual contribution limit. The Company began matching employee contributions as of

July 1, 2016

and paid

$314,000,

$277,000

and

$126,000

in matching contributions in the years ended

December 

31,

2018,

2017

and

2016,

respectively.

In the United Kingdom, the Company has adopted a defined contribution plan (the U.K. Plan) which qualifies under the rules established by HM Revenue & Customs. The U.K. Plan allows all U.K. employees to contribute a minimum of

5%

of salary with

no

maximum limit. The contribution is matched by the Company, up to a maximum of

5%

of salary. The Company paid to the U.K. Plan

$685,000

in contributions in the year ended

December 

31,

2018,

$613,000

in the year ended

December 31, 2017

and

$636,000

in the year ended

December 31, 2016.