OPERATING SEGMENTS (Revenues by Service Offering) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue from External Customer [Line Items]
Revenues	$ 202,184	$ 192,764	$ 174,695	$ 160,384	$ 157,585	$ 140,150	$ 133,184	$ 124,198	$ 730,027	$ 555,117	$ 433,799
Software development
Revenue from External Customer [Line Items]
Revenues									504,590	374,426	290,139
Application testing services
Revenue from External Customer [Line Items]
Revenues									140,363	109,222	85,849
Application maintenance and support
Revenue from External Customer [Line Items]
Revenues									58,840	45,971	36,056
Infrastructure services
Revenue from External Customer [Line Items]
Revenues									14,198	14,433	12,424
Licensing
Revenue from External Customer [Line Items]
Revenues									3,626	3,439	2,914
Reimbursable expenses and other revenues
Revenue from External Customer [Line Items]
Revenues									$ 8,410	$ 7,626	$ 6,417