REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
REVENUE RECOGNITION [Abstract]
Unearned tuition	$ 20,240		$ 23,453
Revenue recognized included in contract liability	20,300
Disaggregation of Revenue [Abstract]
Total revenues	77,996	$ 70,041
Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	4,853	3,571
Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	73,143	66,470
Transportation and Skilled Trades Segment [Member]
Disaggregation of Revenue [Abstract]
Total revenues	55,670	49,056
Transportation and Skilled Trades Segment [Member] | Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	3,520	2,498
Transportation and Skilled Trades Segment [Member] | Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	52,150	46,558
Healthcare and Other Professions Segment [Member]
Disaggregation of Revenue [Abstract]
Total revenues	22,326	20,985
Healthcare and Other Professions Segment [Member] | Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	1,333	1,073
Healthcare and Other Professions Segment [Member] | Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	$ 20,993	$ 19,912