Revenue (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018 USD ($) Obligation	Dec. 31, 2018 USD ($) Stream Obligation	Dec. 31, 2017 USD ($)
Disaggregation of Revenue [Abstract]
Revenue	$ 92,249	$ 92,249	$ 70,880	[1]
Number of broad revenue streams | Stream		3
Contract with Customer, Asset and Liability [Abstract]
Billings in excess of revenue earned (BIE)	$ 10,609	$ 10,609	14,543
Revenue recognized in the period from amounts included in BIE at the beginning of the period		11,275	0
Amount of revenue recognized related to performance obligations satisfied in previous periods		$ 1,988
Revenue, Performance Obligation [Abstract]
Number of performance obligations | Obligation	2	2
Remaining performance obligation	$ 41,640	$ 41,640
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-12-31
Revenue, Performance Obligation [Abstract]
Expected period to recognize revenue as performance obligations are satisfied	12 months	12 months
Performance Improvement Solutions [Member]
Disaggregation of Revenue [Abstract]
Revenue		$ 42,954	39,899
Performance Improvement Solutions [Member] | System Design and Build [Member]
Disaggregation of Revenue [Abstract]
Revenue		25,948	29,217	[1]
Performance Improvement Solutions [Member] | Software [Member]
Disaggregation of Revenue [Abstract]
Revenue		2,883	3,409	[1]
Performance Improvement Solutions [Member] | Training and Consulting Services [Member]
Disaggregation of Revenue [Abstract]
Revenue		14,123	7,273	[1]
Nuclear Industry Training and Consulting [Member]
Disaggregation of Revenue [Abstract]
Revenue		49,295	30,981
Nuclear Industry Training and Consulting [Member] | Training and Consulting Services [Member]
Disaggregation of Revenue [Abstract]
Revenue		$ 49,295	$ 30,981	[1]

[1] Prior period amounts have not been adjusted under the modified retrospective transition method for the adoption of ASC 606.