FAIR VALUE MEASUREMENTS - Estimated Fair values Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Inputs, Level 1 [Member] | Deferred compensation [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Deferred compensation	$ 1,362	$ 1,412
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent purchase price liabilities	4,139	3,686
Fair Value, Inputs, Level 3 [Member] | Convertible Notes, Derivative Liability [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Convertible Notes derivative liability	$ 20,472	$ 33,337