Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Changes in the carrying amount of goodwill
Goodwill, balance beginning	$ 22,208	$ 26,274
Impact of foreign currency translation adjustments	1,881	(4,066)
Goodwill, balance ending	24,089	22,208
E&P Technology & Services
Changes in the carrying amount of goodwill
Goodwill, balance beginning	2,943	2,943
Impact of foreign currency translation adjustments	0	0
Goodwill, balance ending	2,943	2,943
Optimization Software & Services
Changes in the carrying amount of goodwill
Goodwill, balance beginning	19,265	23,331
Impact of foreign currency translation adjustments	1,881	(4,066)
Goodwill, balance ending	$ 21,146	$ 19,265