Revenue (Tables)

3 Months Ended

Mar. 31, 2019

The following table represents a disaggregation of revenue by type of goods or services for the three months ended March 31, 2019 and 2018, along with the reportable segment for each category:

(in thousands)

	Three months ended March 31,
	2019		2018
Performance Improvement Solutions segment
System Design and Build	$	6,442	$	7,495
Software		749		869
Training and Consulting Services		4,999		1,537

Nuclear Industry Training and Consulting segment
Training and Consulting Services		10,004		12,994
Total revenue	$	22,194	$	22,895

Balance of Contract Liabilities and Revenue Recognized in Reporting Period

The following table reflects the balance of contract liabilities and the revenue recognized in the reporting period that was included in the contract liabilities from contracts with customers:

(in thousands)

	March 31, 2019		December 31, 2018
Billings in excess of revenue earned (BIE)	$	7,511	$	10,609
Revenue recognized in the period from amounts included in BIE at the beginning of the period	$	5,040		11,275