FAIR VALUE OF FINANCIAL ASSETS AND LIABILITIES - Reconciliation of Beginning and Ending Balances (Details) - Fair Value, Measurements, Recurring - Fair Value, Inputs, Level 3 - Contingent Consideration Liability $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Contingent Liability for Accrued Consideration
Beginning balance at January 1, 2018	$ 0
Acquisitions and settlements
Acquisition of ASI (Note 15)	4,006
Settlements	0
Total remeasurement adjustments:
Changes in fair value recorded in profit and loss	313
Ending Balance at December 31, 2018	4,319
The amount of total (gains) or losses for the year included in earnings or changes to net assets, attributable to changes in unrealized (gains) or losses relating to assets or liabilities still held at year-end.	$ 313