OPERATING SEGMENTS, Revenues by Service Offering (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Revenue from External Customer [Line Items]
Revenues	$ 236,049	$ 192,764	$ 653,875	$ 527,843
Software development
Revenue from External Customer [Line Items]
Revenues	165,438	134,000	457,216	364,539
Application testing services
Revenue from External Customer [Line Items]
Revenues	46,275	37,155	125,615	103,121
Application maintenance and support
Revenue from External Customer [Line Items]
Revenues	17,976	14,824	53,078	40,715
Infrastructure services
Revenue from External Customer [Line Items]
Revenues	2,689	3,502	8,609	10,740
Licensing
Revenue from External Customer [Line Items]
Revenues	794	820	2,381	2,626
Reimbursable expenses and other revenues
Revenue from External Customer [Line Items]
Revenues	$ 2,877	$ 2,463	$ 6,976	$ 6,102