REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
REVENUE RECOGNITION [Abstract]
Unearned tuition	$ 21,192		$ 25,405
Revenue recognized included in contract liability	21,800
Disaggregation of Revenue [Abstract]
Total revenues	82,554	$ 77,996
Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	4,789	4,853
Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	77,765	73,143
Transportation and Skilled Trades Segment [Member]
Disaggregation of Revenue [Abstract]
Total revenues	58,784	55,670
Transportation and Skilled Trades Segment [Member] | Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	3,410	3,520
Transportation and Skilled Trades Segment [Member] | Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	55,374	52,150
Healthcare and Other Professions Segment [Member]
Disaggregation of Revenue [Abstract]
Total revenues	23,770	22,326
Healthcare and Other Professions Segment [Member] | Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	1,379	1,333
Healthcare and Other Professions Segment [Member] | Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	$ 22,391	$ 20,993