REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
REVENUE RECOGNITION [Abstract]
Unearned tuition	$ 19,354		$ 19,354		$ 23,411
Revenue recognized included in contract liability			23,400
Disaggregation of Revenue [Abstract]
Total revenues	78,792	$ 72,594	211,303	$ 199,427
Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	6,986	6,100	13,535	12,901
Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	71,806	66,494	197,768	186,526
Transportation and Skilled Trades Segment [Member]
Disaggregation of Revenue [Abstract]
Total revenues	56,828	52,652	148,799	141,006
Transportation and Skilled Trades Segment [Member] | Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	5,520	4,792	10,056	9,360
Transportation and Skilled Trades Segment [Member] | Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	51,308	47,860	138,743	131,646
Healthcare and Other Professions Segment [Member]
Disaggregation of Revenue [Abstract]
Total revenues	21,964	19,942	62,504	58,421
Healthcare and Other Professions Segment [Member] | Services Transferred at a Point in Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	1,466	1,308	3,479	3,541
Healthcare and Other Professions Segment [Member] | Services Transferred over Time [Member]
Disaggregation of Revenue [Abstract]
Total revenues	$ 20,498	$ 18,634	$ 59,025	$ 54,880