CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net income	$ 56,818	$ 51,218
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	12,496	14,650
Bad debt expense	910	946
Deferred taxes	535	275
Stock-based compensation expense	33,350	16,524
Excess tax benefit on stock-based compensation plans	(3,118)	(2,551)
Other	2,358	2,607
(Increase)/ decrease in operating assets:
Accounts receivable	(3,575)	(18,126)
Unbilled revenues	(49,110)	(26,070)
Prepaid expenses and other assets	29	525
Increase/ (decrease) in operating liabilities:
Accounts payable	8,128	(264)
Accrued expenses and other liabilities	10,844	6,346
Deferred revenues	(607)	(2,067)
Due to employees	4,295	7,121
Taxes payable	(8,799)	5,035
Net cash provided by operating activities	64,554	56,169
Cash flows from investing activities:
Purchases of property and equipment	(9,533)	(8,164)
Payment for construction of corporate facilities	(4,671)	(3,541)
Employee housing loans issued	(1,993)	(1,316)
Proceeds from repayments of employee housing loans	1,611	1,303
Increase in restricted cash and time deposits, net	(29,947)	307
Increase in other long-term assets, net	(988)	(499)
Acquisition of businesses, net of cash acquired (Note 2)	(27,654)	(26,498)
Net cash used in investing activities	(73,175)	(38,408)
Cash flows from financing activities:
Proceeds related to stock options exercises	17,607	6,808
Excess tax benefit on stock-based compensation plans	3,118	2,551
Proceeds from borrowing under line of credit (Note 5)	15,000	0
Acquisition of business, deferred consideration (Note 2)	(30,274)	0
Net cash provided by financing activities	5,451	9,359
Effect of exchange rate changes on cash and cash equivalents	(2,921)	(5,081)
Net increase/ (decrease) in cash and cash equivalents	(6,091)	22,039
Cash and cash equivalents, beginning of period	220,534	169,207
Cash and cash equivalents, end of period	$ 214,443	$ 191,246