SIGNIFICANT CLIENTS(NARRATIVE) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2018
Entity Wide Revenue Major Customer Line Items
Concentration risk percentage				0.00%
Revenue.	$ 492,980	$ 395,507	$ 1,378,274	$ 1,182,378
Financial Services Client
Entity Wide Revenue Major Customer Line Items
Concentration risk percentage			11.80%	3.40%
Sears
Entity Wide Revenue Major Customer Line Items
Accounts receivable amount from major customer	$ 2,700		$ 2,700		$ 2,700
Minimum | Customer Concentration Risk | Revenue
Entity Wide Revenue Major Customer Line Items
Revenue.			$ 100,000