STOCK-BASED COMPENSATION AND EMPLOYEE BENEFIT PLANS - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 6,769	$ 6,338	$ 5,454
Cost of revenues | State Enterprise
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,499	1,516	1,276
Cost of revenues | Software & services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	101	151	86
Selling & administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	4,495	3,994	3,456
Enterprise technology & product support
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 674	$ 677	$ 636