RESTRUCTURING AND INTEGRATION CHARGES AND IMPAIRMENT LOSSES (LIABILITY CLASSIFICATION TABLE) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Reduction in force									$ 827	$ 1,161	$ 3,400
Facility exit charges									5,304	2,219	992
Restructuring charges, net	$ 1,532	$ 2,716	$ 1,034	$ 849	$ 4,897	$ 6,006	$ 3,593	$ 169	6,131	14,665	4,392
Customer Management Services [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in force									694	1,012	2,837
Facility exit charges									3,550	2,050	959
Customer Growth Services [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in force											147
Facility exit charges									1,754	0	0
Customer Technology Services [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in force										94	324
Facility exit charges									0	84	33
Customer Strategy Services [Member]
Restructuring Cost and Reserve [Line Items]
Reduction in force									133	55	92
Facility exit charges									$ 0	$ 85	$ 0