DISCONTINUED OPERATIONS - Income Statement Disclosures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income (loss) from discontinued operations, net of income taxes	$ 13,618	$ (835)
Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue	108,463	89,413
Gross margin	38,663	32,430
Salaries and related	29,032	24,986
Other selling, general and administrative	8,355	6,952
Depreciation and amortization	680	585
Business reorganization	50	292
Operating income (loss)	546	(385)
Interest income (expense), net	(88)	(88)
Other non-operating income (loss)	216	(345)
Income (Loss) from discontinued operations before taxes and gain (loss) on sale	674	(818)
Gain (loss) from sale of discontinued operations	14,043	0
Income (loss) from discontinued operations before income taxes	14,717	(818)
Provision (benefit) for income taxes	1,099	17
Income (loss) from discontinued operations, net of income taxes	$ 13,618	$ (835)