Business Segments (Details 4) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total assets	$ 365,007	$ 315,601
United States
Segment Reporting Information [Line Items]
Total assets	215,523	195,693
United Kingdom
Segment Reporting Information [Line Items]
Total assets	75,862	59,018
Other Countries
Segment Reporting Information [Line Items]
Total assets	$ 73,622	$ 60,890