ACQUISITIONS (NARRATIVE) (DETAILS) - USD ($) $ in Thousands				12 Months Ended
	Aug. 08, 2014	Feb. 28, 2014	Aug. 09, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Future Value of Liabilities Incurred From Business Acquisitions				$ 13,800
Valuation Technique on Contingent Consideration				Contingent Consideration - The Company recorded contingent consideration related to the acquisitions of iKnowtion, Guidon, TSG, WebMetro, Sofica and rogenSi. These contingent payables were recognized at fair value using a discounted cash flow approach and a discount rate of 21.0%, 21.0%, 4.6%, 5.3%, 5.0%, or 4.6%, respectively. The discount rates vary dependent on the specific risks of each acquisition including the country of operation, the nature of services and complexity of the acquired business, and other factors. These measurements were based on significant inputs not observable in the market. The Company will accrete interest expense each period using the effective interest method until the future value of these contingent payables reaches their expected future value of $13.8 million. Interest expense related to all recorded contingent payables is included in Interest expense in the Consolidated Statements of Comprehensive Income (Loss).
Contingent Consideration, at fair value				$ 13,450	$ 24,744	$ 21,748
Revenue of Acquirees since Acquisition Date, Actual				65,900	43,200	6,400
Income (loss) from operations of Acquirees since Acquisition Date, Actual				600	5,300	900
Business Combination Pro Forma Information Amortization Expense of Acquirees Since Acquisition				4,200	3,300	800
rogenSi [Member]
Business Acquisition [Line Items]
Description of Acquired Entity	rogenSi Worldwide PTY, Ltd., a global leadership, change management, sales, performance training and consulting company
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net	$ 34,403
Cost of Acquired Entity, Up Front Cash Consideration	18,000
Future Value of Liabilities Incurred From Business Acquisitions	$ 15,300
Valuation Technique on Contingent Consideration	The fair value of the contingent consideration was measured by applying a probability weighted discounted cash flow model based on significant inputs not observable in the market (Level 3 inputs). Key assumptions include a discount rate of 4.6% and expected future value of payments of $15.3 million. The $15.3 million of expected future payments was calculated using a probability weighted EBITDA assessment with the highest probability associated with rogenSi achieving the targeted EBITDA for each earn-out year.
Acquisition hold-back payment	$ 1,800
Discount rate	4.60%
Contingent Consideration Arrangements, Basis for Amount	The total contingent consideration possible per the sale and purchase agreement ranges from zero to $17.6 million and the earn-out payments are payable in early 2015, 2016 and 2017, based on July 1, 2014 through December 31, 2014, and full year 2015 and 2016 performance, respectively.
Contingent Consideration, at fair value	$ 14,500			9,797	15,162	0
Measurement period adjustment - Other accrued expenses				5,700
Measurement period adjustment - Other noncurrent liabilities				$ 4,100
rogenSi [Member] | Customer Relationships [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life				70 months
rogenSi [Member] | Non-compete agreements useful lives [Member]
Business Acquisition [Line Items]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life				30 months
Sofica [Member]
Business Acquisition [Line Items]
Percentage of Voting Interests Acquired		100.00%
Description of Acquired Entity		Sofica provides customer lifecycle management and other business process services across multiple channels in multiple sites in over 18 languages.
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net		$ 14,200
Cost of Acquired Entity, Up Front Cash Consideration		9,400
Future Value of Liabilities Incurred From Business Acquisitions		$ 3,800
Valuation Technique on Contingent Consideration		The fair value of the contingent consideration was measured based on significant inputs not observable in the market (Level 3 inputs). Key assumptions include a discount rate of 5.0% and expected future value of payments of $4.0 million. The $4.0 million of expected future payments was calculated using a probability weighted EBITDA assessment with the highest probability associated with Sofica achieving the targeted EBITDA for each earn-out year.
Acquisition hold-back payment		$ 1,000
Discount rate		5.00%
Contingent Consideration Arrangements, Basis for Amount		The total contingent consideration possible per the stock purchase agreement ranges from zero to $7.5 million. Additionally, the purchase price includes a $1.0 million hold-back payment for contingencies as defined in the stock purchase agreement which will be paid in the second quarter of 2016, if required.
Contingent Consideration, at fair value		$ 4,000		$ 3,153	6,317	0
WebMetro [Member]
Business Acquisition [Line Items]
Percentage of Voting Interests Acquired			100.00%
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net			$ 17,800
Future Value of Liabilities Incurred From Business Acquisitions			$ 2,600
Valuation Technique on Contingent Consideration				The fair value of the contingent payments was measured based on significant inputs not observable in the market (Level 3 inputs). Key assumptions include a discount rate of 5.3% and expected future value of payments of $2.6 million. The $2.6 million of expected future payments was calculated using probability weighted EBITDA assessment with the highest probability associated with WebMetro achieving the targeted EBITDA for each earn-out year.
Discount rate			5.30%
Contingent Consideration, at fair value			$ 2,500	$ 0	$ 0	$ 2,708