CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 180,291	$ 103,634
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	26,457	20,866
Bad debt expense	1,765	79
Deferred taxes	(36,372)	1,386
Stock-based compensation expense	46,736	39,920
Other	(3,434)	(3,496)
(Increase)/decrease in operating assets:
Accounts receivable	(16,258)	(24,396)
Unbilled revenues	(41,544)	(42,540)
Prepaid expenses and other assets	(1,765)	2,036
Increase/(decrease) in operating liabilities:
Accounts payable	1,574	1,885
Accrued expenses and other liabilities	9,625	18,725
Due to employees	4,009	5,939
Taxes payable	(1,996)	(2,458)
Net cash provided by operating activities	169,088	121,580
Cash flows from investing activities:
Purchases of property and equipment	(27,465)	(16,881)
Employee housing loans issued	(264)	(618)
Proceeds from repayments of employee housing loans	1,213	1,897
Decrease/(increase) in time deposits, net	418	(408)
Acquisition of businesses, net of cash acquired	(50,264)	(6,810)
Other investing activities, net	(1,471)	(1,304)
Net cash used in investing activities	(77,833)	(24,124)
Cash flows from financing activities:
Proceeds from stock option exercises	32,007	44,315
Payments of withholding taxes related to net share settlements of restricted stock units	(7,068)	(3,088)
Proceeds from debt (Note 6)	0	25,000
Repayment of debt (Note 6)	(3,485)	(25,089)
Other financing activities, net	(603)	(922)
Net cash provided by financing activities	20,851	40,216
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(8,660)	10,435
Net increase in cash, cash equivalents and restricted cash	103,446	148,107
Cash, cash equivalents and restricted cash, beginning of period	582,855	364,664
Cash, cash equivalents and restricted cash, end of period	$ 686,301	$ 512,771