Discontinued Operations - Summary Of Financial Information That Has Been Segregated From Continuing Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Discontinued Operations:
Net loss from discontinued operations	$ 0	$ (11,235)
Discontinued Operations, Held-for-sale | Drilling Technologies
Discontinued Operations:
Revenue		6,797
Cost of revenue		(4,655)
Selling, general and administrative		(3,031)
Gain on disposal of long-lived assets		73
Loss from operations		(816)
Other expense		(71)
Loss on write-down of assets held for sale		(6,560)
Loss before income taxes		(7,447)
Income tax benefit		2,713
Net loss from discontinued operations		(4,734)
Discontinued Operations, Held-for-sale | Production Technologies
Discontinued Operations:
Revenue		3,153
Cost of revenue		(2,483)
Selling, general and administrative		(873)
Research and development		(271)
Loss from operations		(474)
Other expense		(36)
Loss on write-down of assets held for sale		(9,717)
Loss before income taxes		(10,227)
Income tax benefit		3,726
Net loss from discontinued operations		(6,501)
Discontinued Operations, Held-for-sale | Drilling Technologies And Production Technologies
Discontinued Operations:
Gain (loss) from discontinued operations		$ (11,235)