Consolidated Statements of Cash Flow (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$ 9,567	$ 11,147
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	7,053	6,356
Stock-based compensation expense	4,255	4,176
Unrealized foreign exchange loss	284	1,895
Deferred income taxes	2,804	1,863
Others, net	(13)	22
Change in operating assets and liabilities:
Restricted cash	(1,477)	(502)
Accounts receivable	(5,779)	(1,713)
Prepaid expenses and other current assets	(2,799)	(4,187)
Accounts payable	(984)	(124)
Deferred revenue	3,834	902
Accrued employee cost	(16,398)	(11,493)
Accrued expenses and other liabilities	(497)	(985)
Advance income tax, net	544	(1,822)
Other assets	(257)	(570)
Net cash provided by operating activities	137	4,965
Cash flows from investing activities:
Purchase of fixed assets	(8,845)	(10,679)
Business acquisition (net of cash acquired)	(44,419)
Purchase of short-term investments	(5,995)	(1,005)
Proceeds from redemption of short-term investments	3,079
Net cash used for investing activities	(56,180)	(11,684)
Cash flows from financing activities:
Principal payments on capital lease obligations	(223)	(288)
Proceeds from long-term borrowings	25,000
Proceeds from short-term borrowings	5,000
Payment of debt issuance costs	(50)
Acquisition of treasury stock	(397)	(459)
Proceeds from exercise of stock options	1,883	1,673
Net cash provided by financing activities	31,213	926
Effect of exchange rate changes on cash and cash equivalents	(350)	1,420
Net decrease in cash and cash equivalents	(25,180)	(4,373)
Cash and cash equivalents, beginning of period	176,499	148,065
Cash and cash equivalents, end of period	$ 151,319	$ 143,692