CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 43,235	$ 39,485
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	11,377	7,674
Bad debt provision	988	465
Deferred taxes	735	(374)
Stock-based compensation expense	9,791	5,369
Excess tax benefit on stock-based compensation plans	(4,924)	(1,635)
Non-cash stock charge	0	640
Other	1,140	(30)
(Increase)/ decrease in operating assets:
Accounts receivable	(11,089)	(6,083)
Unbilled revenues	(31,373)	(19,424)
Prepaid expenses and other assets	1,422	1,243
Increase/ (decrease) in operating liabilities:
Accounts payable	2,475	(2,098)
Accrued expenses and other liabilities	(10,822)	(11,318)
Deferred revenue	(3,811)	(3,387)
Due to employees	2,581	3,571
Taxes payable	70	(1,358)
Net cash provided by operating activities	11,795	12,740
Cash flows used in investing activities:
Purchases of property and equipment	(10,928)	(10,317)
Payment for construction of corporate facilities	(3,508)	(13,416)
Employee housing loans	(7,045)	0
Proceeds from repayments of employee housing loans	1,270	0
Decrease/ (increase) in restricted cash, net	1,679	(52)
Increase in other long-term assets, net	(323)	(588)
Acquisitions of businesses, net of cash acquired	(20)	(6,990)
Net cash used in investing activities	(18,875)	(31,363)
Cash flows from financing activities:
Proceeds related to stock options exercises	7,783	2,495
Excess tax benefit on stock-based compensation plans	4,924	1,635
Net proceeds from issuance of common stock in initial public offering	0	32,364
Costs related to stock issue	0	(1,766)
Repurchase of common stock	0	(61)
Net cash provided by financing activities	12,707	34,667
Effect of exchange rate changes on cash and cash equivalents	(760)	1,045
Net increase in cash and cash equivalents	4,867	17,089
Cash and cash equivalents, beginning of period	118,112	88,796
Cash and cash equivalents, end of period	$ 122,979	$ 105,885