FINANCING ARRANGEMENTS AND LONG-TERM DEBT - Compass Convertible Notes and Alsbridge Notes(Details) $ / shares in Units, $ in Thousands			6 Months Ended
	Jan. 04, 2018 USD ($)	Jan. 04, 2011 USD ($) $ / shares	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Dec. 01, 2016 USD ($)
FINANCING ARRANGEMENTS AND LONG-TERM DEBT
Amount outstanding			$ 110,200		$ 116,700
Payment of compass notes			6,511	$ 2,768
C C G H Limited | Convertible Notes Payable
FINANCING ARRANGEMENTS AND LONG-TERM DEBT
Proceeds from debt		$ 6,300
Rate of interest (as a percent)		3.875%
Trigger event condition related to number of consecutive trading days on which market price of common stock exceeds $4 per share on the Nasdaq Global Market		60 days
Conversion rate		0.25
Written notice period after trigger event, that company need to serve for prepayment of all or portion of the outstanding principal amount of the Notes		30 days
Payment of compass notes	$ 200
Alsbridge | Note payable
FINANCING ARRANGEMENTS AND LONG-TERM DEBT
Rate of interest (as a percent)						2.00%
Long-term Debt			$ 7,000
Unsecured subordinated promissory notes issued						$ 7,000
Minimum | C C G H Limited | Convertible Notes Payable
FINANCING ARRANGEMENTS AND LONG-TERM DEBT
Trigger Event condition related to minimum market price of common stock on the Nasdaq Global market (in dollars per share) | $ / shares		$ 4