Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net income	$ 16,788	$ 13,820
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	9,426	8,133
Stock-based compensation expense	5,956	5,809
Unrealized gain on short term investments	0	(1,525)
Change in fair value of earn-out consideration	0	(250)
Unrealized foreign exchange loss/(gain)	2,225	(1,061)
Deferred income taxes	(4,256)	3,646
Others, net	(7)	(12)
Change in operating assets and liabilities:
Restricted cash	1,050	(919)
Accounts receivable	(6,340)	(14,490)
Prepaid expenses and other current assets	(1,285)	(3,641)
Accounts payable	2,185	(2,584)
Deferred revenue	1,480	2,334
Accrued employee costs	(21,053)	(19,567)
Accrued expenses and other liabilities	806	4,147
Advance income tax, net	(1,471)	(4,429)
Other assets	1,569	148
Net cash provided by/(used for) operating activities	7,073	(10,441)
Cash flows from investing activities:
Purchase of property, plant and equipment	(10,114)	(8,457)
Purchase of short-term investments	(129,837)	(101,327)
Proceeds from redemption of short-term investments	22,879	20,004
Net cash used for investing activities	(117,072)	(89,780)
Cash flows from financing activities:
Principal payments on capital lease obligations	(43)	(123)
Repayments of borrowings	0	(5,000)
Acquisition of treasury stock	(11,913)	(6,855)
Proceeds from exercise of stock options	191	2,010
Net cash used for financing activities	(11,765)	(9,968)
Effect of exchange rate changes on cash and cash equivalents	309	640
Net decrease in cash and cash equivalents	(121,455)	(109,549)
Cash and cash equivalents, beginning of period	213,155	205,323
Cash and cash equivalents, end of period	$ 91,700	$ 95,774