STOCK-BASED COMPENSATION (Costs Related to Stock Compensation Plans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 45,833	$ 24,620	$ 13,150
Cost of revenues | Organic growth
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	13,695	8,648	4,823
Selling, general and administrative expenses - All other | Organic growth
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	13,448	7,143	3,910
Selling, general and administrative expenses - All other | Business acquisitions
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 18,690	$ 8,829	$ 4,417