GOODWILL AND LONG-LIVED ASSETS (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($) Unit	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
GOODWILL AND LONG-LIVED ASSETS [Abstract]
Number of reporting units impaired | Unit				1
Impairment of long-lived assets	$ 0	$ 0	$ 0	$ 0
Changes in carrying amount of goodwill [Abstract]
Gross Goodwill Balance		115,872		115,872	$ 108,417	$ 108,417	$ 115,872
Accumulated Impairment Losses		(93,881)		(93,881)	(93,881)	(93,881)	(93,665)
Adjustments			0	(216)
Net Goodwill Balance		21,991		21,991	14,536	$ 14,536	$ 22,207
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount, beginning balance			470
Adjustments			0
Gross carrying amount, ending balance	470		470
Accumulated amortization, beginning balance			420
Amortization			13
Accumulated amortization, ending balance	433		433
Net carrying amount	37		37
Amortization of intangible assets			13
Estimated future amortization expense [Abstract]
Remainder of 2016					4
2017					16
2018					17
Total	37		37		37
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization	100	100	100	100
Amortization of intangible assets	100	$ 100	100	$ 100
Trade Name [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount, beginning balance			310
Adjustments			0
Gross carrying amount, ending balance	310		310
Accumulated amortization, beginning balance			308
Amortization			2
Accumulated amortization, ending balance	310		310
Net carrying amount	0		$ 0
Weighted average amortization period			7 years
Amortization of intangible assets			$ 2
Estimated future amortization expense [Abstract]
Total	0		0		0
Curriculum [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount, beginning balance			160
Adjustments			0
Gross carrying amount, ending balance	160		160
Accumulated amortization, beginning balance			112
Amortization			11
Accumulated amortization, ending balance	123		123
Net carrying amount	37		$ 37
Weighted average amortization period			10 years
Amortization of intangible assets			$ 11
Estimated future amortization expense [Abstract]
Total	$ 37		$ 37		$ 37