SEGMENT INFORMATION (SEGMENT FINANCIALS) (DETAILS) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Net Revenue	$ 344,947	$ 312,796	$ 305,105	$ 312,410	$ 341,816	$ 309,195	$ 310,223	$ 325,521	$ 1,275,258	$ 1,286,755	$ 1,241,781
Depreciation and amortization	16,914	16,811	17,221	17,729	17,279	15,486	15,680	15,363	68,675	63,808	56,538
Income (Loss) from Operations	6,245	$ 12,526	$ 16,228	$ 17,753	25,075	$ 15,625	$ 23,352	$ 26,128	52,752	90,180	96,475
Capital Expenditures									50,832	66,595	67,641
Total Assets	846,304				843,327				846,304	843,327	852,475
Goodwill	129,648				114,183				129,648	114,183	128,705
Operating Segments
Segment Reporting Information [Line Items]
Net Revenue									1,276,198	1,286,987	1,241,817
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue									(940)	(232)	(36)
Customer Management Services
Segment Reporting Information [Line Items]
Net Revenue									924,325	913,272	923,497
Depreciation and amortization									48,770	44,633	40,577
Income (Loss) from Operations									50,541	58,018	76,792
Capital Expenditures									40,321	56,570	49,630
Total Assets	585,679				525,470				585,679	525,470	528,705
Goodwill	42,589				23,218				42,589	23,218	27,080
Customer Management Services | Operating Segments
Segment Reporting Information [Line Items]
Net Revenue									924,654	913,272	923,497
Customer Management Services | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue									(329)	0	0
Customer Growth Services
Segment Reporting Information [Line Items]
Net Revenue									141,005	129,021	115,434
Depreciation and amortization									5,905	6,065	6,048
Income (Loss) from Operations									6,969	3,077	7,255
Capital Expenditures									4,185	4,681	3,195
Total Assets	71,540				75,291				71,540	75,291	88,394
Goodwill	24,439				24,439				24,439	24,439	30,395
Customer Growth Services | Operating Segments
Segment Reporting Information [Line Items]
Net Revenue									141,005	129,021	115,434
Customer Growth Services | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue									0	0	0
Customer Technology Services
Segment Reporting Information [Line Items]
Net Revenue									141,254	157,606	139,182
Depreciation and amortization									10,645	9,775	7,489
Income (Loss) from Operations									933	13,339	4,519
Capital Expenditures									5,217	4,216	14,423
Total Assets	115,537				146,480				115,537	146,480	145,693
Goodwill	41,500				41,500				41,500	41,500	41,500
Customer Technology Services | Operating Segments
Segment Reporting Information [Line Items]
Net Revenue									141,865	157,838	139,218
Customer Technology Services | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue									(611)	(232)	(36)
Customer Strategy Services
Segment Reporting Information [Line Items]
Net Revenue									68,674	86,856	63,668
Depreciation and amortization									3,355	3,335	2,424
Income (Loss) from Operations									(5,691)	15,746	7,909
Capital Expenditures									1,109	1,128	393
Total Assets	73,548				96,086				73,548	96,086	89,683
Goodwill	$ 21,120				$ 25,026				21,120	25,026	29,730
Customer Strategy Services | Operating Segments
Segment Reporting Information [Line Items]
Net Revenue									68,674	86,856	63,668
Customer Strategy Services | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue									$ 0	$ 0	$ 0