CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income	$ 114,673	$ 61,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	17,138	13,692
Bad debt expense	1,529	102
Deferred taxes	(27,581)	(766)
Stock-based compensation expense	31,406	28,703
Other	(2,099)	(1,550)
(Increase)/decrease in operating assets:
Accounts receivable	(15,051)	(4,630)
Unbilled revenues	(35,334)	(44,133)
Prepaid expenses and other assets	(4,495)	973
Increase/(decrease) in operating liabilities:
Accounts payable	1,008	518
Accrued expenses and other liabilities	(15,861)	(3,333)
Due to employees	1,351	4,549
Taxes payable	105	4,208
Net cash provided by operating activities	66,789	59,333
Cash flows from investing activities:
Purchases of property and equipment	(19,303)	(11,441)
Employee housing loans issued	(214)	(512)
Proceeds from repayments of employee housing loans	919	1,315
Decrease in time deposits, net	418	13
Acquisition of businesses, net of cash acquired	(50,264)	(6,810)
Other investing activities, net	130	(190)
Net cash used in investing activities	(68,314)	(17,625)
Cash flows from financing activities:
Proceeds from stock option exercises	22,368	37,757
Payments of withholding taxes related to net share settlements of restricted stock units	(6,696)	(2,702)
Proceeds from debt (Note 6)	0	25,000
Repayment of debt (Note 6)	(3,478)	(25,059)
Other financing activities, net	(603)	(864)
Net cash provided by financing activities	11,591	34,132
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(7,645)	5,912
Net increase in cash, cash equivalents and restricted cash	2,421	81,752
Cash, cash equivalents and restricted cash, beginning of period	582,855	364,664
Cash, cash equivalents and restricted cash, end of period	$ 585,276	$ 446,416