SIGNIFICANT CLIENTS(NARRATIVE) (DETAILS) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) customer	Sep. 30, 2016 USD ($) customer
Entity Wide Revenue Major Customer Line Items
Revenue	$ 359,036	$ 312,796	$ 1,050,742	$ 930,311
Customer Management Services
Entity Wide Revenue Major Customer Line Items
Revenue	$ 277,373	$ 223,664	$ 798,508	$ 664,392
Customer Concentration Risk | Revenue
Entity Wide Revenue Major Customer Line Items
Number of customers | customer			0	1
Customer Concentration Risk | Revenue | Client A [Member] | Customer Management Services
Entity Wide Revenue Major Customer Line Items
Concentration risk percentage			9.50%	10.40%
Minimum | Customer Concentration Risk | Revenue
Entity Wide Revenue Major Customer Line Items
Revenue			$ 100,000