Discontinued Operations - Summary Of Financial Information That Has Been Segregated From Continuing Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Discontinued Operations:
Net loss from discontinued operations	$ 0	$ (2,704)	$ 0	$ (13,937)
Discontinued Operations, Held-for-sale | Drilling Technologies
Discontinued Operations:
Revenue		4,737		11,534
Cost of revenue		(2,603)		(7,259)
Selling, general and administrative		(2,740)		(5,771)
Research and development		(6)		(6)
(Loss) gain on disposal of long-lived assets		(12)		62
Loss from operations		(624)		(1,440)
Other expense		(46)		(117)
Gain (loss) from sale of business		(1,365)		(1,365)
Loss on write-down of assets held for sale		(272)		(6,831)
Loss before income taxes		(2,307)		(9,753)
Income tax benefit		158		3,147
Net loss from discontinued operations		(2,149)		(6,606)
Discontinued Operations, Held-for-sale | Production Technologies
Discontinued Operations:
Revenue		849		4,002
Cost of revenue		(707)		(3,189)
Selling, general and administrative		(802)		(1,675)
Research and development		(92)		(363)
Loss from operations		(752)		(1,225)
Other expense		(16)		(52)
Gain (loss) from sale of business		171		171
Loss on write-down of assets held for sale		0		(9,718)
Loss before income taxes		(597)		(10,824)
Income tax benefit		42		3,493
Net loss from discontinued operations		(555)		(7,331)
Discontinued Operations, Held-for-sale | Drilling Technologies And Production Technologies
Discontinued Operations:
Net loss from discontinued operations		$ (2,704)		$ (13,937)