CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities:
Net income	$ 103,634	$ 74,503
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	20,866	17,150
Bad debt expense	79	1,690
Deferred income taxes	1,386	(11)
Stock-based compensation expense	39,920	37,520
Excess tax benefit on stock-based compensation plans	0	(4,769)
Other	(3,496)	1,834
(Increase) decrease in operating assets:
Accounts receivable	(24,396)	(14,801)
Unbilled revenues	(42,540)	15,633
Prepaid expenses and other assets	4,436	(630)
Increase (decrease) in operating liabilities:
Accounts payable	1,885	2,011
Accrued expenses and other liabilities	18,725	(26,402)
Due to employees	5,939	8,047
Taxes payable	(2,458)	(609)
Net cash provided by operating activities	123,980	111,166
Cash flows from investing activities:
Purchases of property and equipment	(16,881)	(19,981)
Employee housing loans issued	(618)	(1,361)
Proceeds from repayments of employee housing loans	1,897	1,597
(Increase) decrease in restricted cash and time deposits, net	(268)	30,001
Acquisition of businesses, net of cash acquired	(6,840)	(4,499)
Other investing activities, net	(1,304)	(2,647)
Net cash (used in) provided by investing activities	(24,014)	3,110
Cash flows from financing activities:
Proceeds from stock option exercises	44,315	15,850
Excess tax benefit on stock-based compensation plans	0	4,769
Payments of withholding taxes related to net share settlements of restricted stock units	(3,088)	0
Proceeds from debt (Note 4)	25,000	20,000
Repayment of debt (Note 4)	(25,089)	(22,096)
Acquisition of business, deferred consideration	0	(2,260)
Other financing activities, net	(922)	135
Net cash provided by financing activities	40,216	16,398
Effect of exchange rate changes on cash and cash equivalents	10,286	504
Net increase in cash and cash equivalents	150,468	131,178
Cash and cash equivalents, beginning of period	362,025	199,449
Cash and cash equivalents, end of period	$ 512,493	$ 330,627