ACQUISITIONS AND DIVESTITURES (NARRATIVE) (DETAILS) $ in Thousands, CAD in Millions		2 Months Ended	3 Months Ended						7 Months Ended	9 Months Ended
	Nov. 09, 2016 CAD	Feb. 28, 2014 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Aug. 08, 2014 USD ($)	Sep. 30, 2016 USD ($)	Nov. 09, 2016 USD ($)
Business Acquisition [Line Items]
Contingent Consideration, at fair value				$ 13,450
Increase (decrease) in contingent consideration payable			$ (4,300)
Loss on assets held-for-sale			5,300							$ 5,300
Customer Growth Services | Business unit 1 [Member]
Business Acquisition [Line Items]
Loss on assets held-for-sale			2,600
Customer Strategy Services | Business unit 2 [Member]
Business Acquisition [Line Items]
Loss on assets held-for-sale			$ 2,700
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									$ 34,400
Cost of Acquired Entity, Up Front Cash Consideration									18,100
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				9,797					$ 14,500
Increase (decrease) in contingent consideration payable				(300)	$ 800		$ 500
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 ranged from zero to $7.5 million. Additionally, the purchase price included a $1.0 million hold-back payment for contingencies, as defined in the stock purchase agreement, which was paid in the first quarter of 2016.
Contingent Consideration, at fair value		$ 4,000		$ 3,153
Increase (decrease) in contingent consideration payable						$ 500	$ 600	$ 1,800
Atelka [Member]
Business Acquisition [Line Items]
Description of Acquired Entity	AtelkaOn November 9, 2016, the Company acquired all of the outstanding shares of Atelka Enterprise Inc. ("Atelka"), a Canadian customer contact center management and business process outsourcing services company that serves Canadian telecommunications, logistics, and entertainment clients. Atelka employs approximately 2,800 in Quebec, Ontario, New Brunswick and Prince Edward Island.
Atelka [Member] | CAD
Business Acquisition [Line Items]
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net | CAD	CAD 59.0
Acquisition hold-back payment | CAD	CAD 2.0
Atelka [Member] | United States of America, Dollars
Business Acquisition [Line Items]
Business Acquisition, Purchase Price Allocation, Assets Acquired (Liabilities Assumed), Net											$ 44,000