Segment Reporting Revenue by Product Sales and Services (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue from External Customer [Line Items]
Revenue	$ 173,207	$ 182,146	$ 175,475	$ 170,018	$ 170,111	$ 162,887	$ 158,212	$ 156,609	$ 700,846	$ 647,819	$ 590,232
Service [Member]
Revenue from External Customer [Line Items]
Revenue									486,820	480,264	468,388
Service [Member] | Reservoir Description [Member]
Revenue from External Customer [Line Items]
Revenue									387,098	393,742	400,034
Service [Member] | Production Enhancement [Member]
Revenue from External Customer [Line Items]
Revenue									99,722	86,522	68,354
Product [Member]
Revenue from External Customer [Line Items]
Revenue									214,026	167,555	121,844
Product [Member] | Reservoir Description [Member]
Revenue from External Customer [Line Items]
Revenue									25,984	21,478	26,171
Product [Member] | Production Enhancement [Member]
Revenue from External Customer [Line Items]
Revenue									$ 188,042	$ 146,077	$ 95,673