REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
REVENUE RECOGNITION [Abstract]
Unearned tuition	$ 23,453	$ 23,411
Revenue recognized included in contract liability	23,400
Disaggregation of Revenue [Abstract]
Total revenues	293,095	273,342
Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	17,237	16,402
Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	275,858	256,940
Transportation and Skilled Trades Segment [Member]
Disaggregation of Revenue [Abstract]
Total revenues	207,434	193,722
Transportation and Skilled Trades Segment [Member] | Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	12,519	11,881
Transportation and Skilled Trades Segment [Member] | Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	194,915	181,841
Healthcare and Other Professions Segment [Member]
Disaggregation of Revenue [Abstract]
Total revenues	85,661	79,620
Healthcare and Other Professions Segment [Member] | Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	4,718	4,521
Healthcare and Other Professions Segment [Member] | Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	$ 80,943	$ 75,099