Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Cash flows from operating activities:
Net income	$ 46,245	$ 36,803
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	25,000	23,171
Stock-based compensation expense	14,743	12,280
Unrealized gain on short term investments	(4,955)	(2,179)
Unrealized foreign exchange gain	(147)	(2,850)
Deferred income taxes	4,424	3,596
Change in fair value of earn-out consideration	(4,060)	0
Others, net	(84)	(249)
Change in operating assets and liabilities (net of effect of acquisitions):
Restricted cash	(464)	(1,313)
Accounts receivable	(16,522)	(14,647)
Prepaid expenses and other current assets	(587)	977
Accounts payable	(2,518)	(1,602)
Deferred revenue	(1,485)	(915)
Accrued employee costs	(3,812)	460
Accrued expenses and other liabilities	5,688	(3,973)
Advance income tax, net	(4,748)	5,751
Other assets	(676)	(760)
Net cash provided by operating activities	56,042	54,550
Cash flows from investing activities:
Purchase of fixed assets	(20,335)	(21,127)
Business acquisition (net of cash acquired)	(9,427)	(44,270)
Purchase of short-term investments	(155,709)	(109,162)
Proceeds from redemption of short-term investments	59,229	28,640
Net cash used for investing activities	(126,242)	(145,919)
Cash flows from financing activities:
Principal payments on capital lease obligations	(292)	(559)
Proceeds from borrowings	0	30,000
Repayments of borrowings	(25,000)	(10,000)
Payment of debt issuance costs	0	(74)
Acquisition of treasury stock	(15,169)	(13,015)
Proceeds from exercise of stock options	6,226	3,162
Net cash (used)/provided by financing activities	(34,235)	9,514
Effect of exchange rate changes on cash and cash equivalents	(2,514)	(3,988)
Net decrease in cash and cash equivalents	(106,949)	(85,843)
Cash and cash equivalents, beginning of period	205,323	176,499
Cash and cash equivalents, end of period	$ 98,374	$ 90,656