SEGMENT INFORMATION (SEGMENT FINANCIALS) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Net Revenue	$ 364,936	$ 359,036	$ 1,090,038	$ 1,050,742
Depreciation and amortization	17,317	16,515	52,052	47,273
Income (Loss) from Operations	14,657	15,800	53,101	63,879
Capital Expenditures	14,958	14,343	31,841	43,932
Total Assets	1,038,606		1,038,606		$ 1,078,736
Goodwill	201,826		201,826		206,694
Operating Segments
Segment Reporting Information [Line Items]
Net Revenue	365,106	359,131
Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue	(170)	(95)
Customer Management Services [Member]
Segment Reporting Information [Line Items]
Net Revenue	262,360	277,373	817,214	798,508
Depreciation and amortization	14,344	13,455	43,594	37,843
Income (Loss) from Operations	3,639	9,133	25,627	43,804
Capital Expenditures	12,853	12,732	28,394	36,701
Total Assets	791,362		791,362		869,594
Goodwill	113,786		113,786		119,497
Customer Management Services [Member] | Operating Segments
Segment Reporting Information [Line Items]
Net Revenue	262,360	277,373	817,214	798,527
Customer Management Services [Member] | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue	0			(19)
Customer Growth Services [Member]
Segment Reporting Information [Line Items]
Net Revenue	35,897	30,829	103,577	96,890
Depreciation and amortization	657	717	1,908	2,249
Income (Loss) from Operations	2,549	1,564	6,895	6,295
Capital Expenditures		346		708
Total Assets	43,387		43,387		41,036
Goodwill	24,439		24,439		24,439
Customer Growth Services [Member] | Operating Segments
Segment Reporting Information [Line Items]
Net Revenue	35,897	30,829	103,577	96,890
Customer Growth Services [Member] | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue	0			0
Customer Technology Services [Member]
Segment Reporting Information [Line Items]
Net Revenue	49,967	34,563	118,991	105,054
Depreciation and amortization	1,842	1,772	5,052	5,377
Income (Loss) from Operations	6,778	4,158	17,188	11,034
Capital Expenditures	1,730	1,180	2,786	6,025
Total Assets	141,397		141,397		100,351
Goodwill	42,223		42,223		40,839
Customer Technology Services [Member] | Operating Segments
Segment Reporting Information [Line Items]
Net Revenue	50,137	34,658	119,280	105,337
Customer Technology Services [Member] | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue	(170)	(95)	(289)	(283)
Customer Strategy Services [Member]
Segment Reporting Information [Line Items]
Net Revenue	16,712	16,271	50,256	50,290
Depreciation and amortization	474	571	1,498	1,804
Income (Loss) from Operations	1,691	945	3,391	2,746
Capital Expenditures	375	85	661	498
Total Assets	62,460		62,460		67,755
Goodwill	21,378		21,378		$ 21,919
Customer Strategy Services [Member] | Operating Segments
Segment Reporting Information [Line Items]
Net Revenue	16,712	$ 16,271	$ 50,256	50,290
Customer Strategy Services [Member] | Intersegment Eliminations
Segment Reporting Information [Line Items]
Net Revenue	$ 0			$ 0