ACQUISITIONS AND DIVESTITURES (DETAILS) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Assets and Liabilities Held for Sale [Line Items]
Loss on assets held-for-sale	$ 5,300	$ 3,178	$ 5,300
Total assets held for sale		9,279		$ 10,715
Total liabilities held for sale		2,491		$ 1,357
Disposal Group, Held-for-sale, Not Discontinued Operations | Customer Growth Services
Assets and Liabilities Held for Sale [Line Items]
Loss on assets held-for-sale	2,600
Disposal Group, Held-for-sale, Not Discontinued Operations | Customer Strategy Services
Assets and Liabilities Held for Sale [Line Items]
Loss on assets held-for-sale	$ 2,700
Disposal Group, Held-for-sale, Not Discontinued Operations | Business Unit From Customer Growth Services And Customer Strategy Services Segments
Assets and Liabilities Held for Sale [Line Items]
Accounts receivable, net - assets held for sale		8,240
Allowance for doubtful accounts of assets held for sale		(51)
Other assets held for sale		589
Property, Plant and Equipment - assets held for sale		1,229
Goodwill - assets held for sale		3,033
Allowance for reduction of assets held for sale		(8,478)
Total assets held for sale		9,279
Accounts payable held for sale		1,046
Accrued employee compensation and benefits		817
Accrued expenses.		316
Other liabilities held for sale		312
Total liabilities held for sale		2,491
Customer Relationships | Disposal Group, Held-for-sale, Not Discontinued Operations | Business Unit From Customer Growth Services And Customer Strategy Services Segments
Assets and Liabilities Held for Sale [Line Items]
Intangible assets held for sale		3,946
Other Intangible Assets | Disposal Group, Held-for-sale, Not Discontinued Operations | Business Unit From Customer Growth Services And Customer Strategy Services Segments
Assets and Liabilities Held for Sale [Line Items]
Intangible assets held for sale		$ 771