Goodwill (Tables)

12 Months Ended

Dec. 31, 2017

Goodwill [Line Items]

Schedule of Goodwill [Table Text Block]

The changes in the carrying amount of goodwill for each reportable segment for the years ended December 31, 2017, and 2016 were as follows (in thousands):

	Reservoir Description		Production Enhancement		Total
Balance at December 31, 2015	$	98,599	$	79,560	$	178,159
Goodwill acquired during the year	885		—		885
Balance at December 31, 2016	99,484		79,560		179,044
Goodwill acquired during the year	—		—		—
Balance at December 31, 2017	$	99,484	$	79,560	$	179,044