Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Operating activities
Net income	$ 96,179	$ 91,273
Adjustments to reconcile net income to net cash (used for)/ provided by operating activities:
Depreciation and amortization	24,847	28,953
Amortization of debt issuance costs	690	557
Amortization of acquired intangible assets	11,306	16,176
Write-down of intangible assets and property, plant and equipment	0	836
Allowance for credit losses	(463)	727
Unrealized gain on revaluation of foreign currency asset/liability	(4,599)	(3,127)
Stock-based compensation expense	15,250	17,430
Deferred tax expense	4,914	31
Others, net	19	201
Change in operating assets and liabilities:
Increase in accounts receivable	(83,548)	(6,385)
(Increase) decrease in prepaid expenses, other current assets, contract cost assets, operating lease right-of-use assets and other assets	(4,120)	14,526
Increase (decrease) in accounts payable	(2,010)	7,700
Decrease in accrued expenses, other current liabilities, operating leases liabilities and other liabilities	(179,186)	(106,727)
Increase in income taxes payable	6,440	14,985
Net cash (used for)/ provided by operating activities	(114,281)	77,156
Investing activities
Purchase of property, plant and equipment	(16,744)	(12,010)
Payment for internally generated intangible assets (including intangibles under development)	(1,065)	(1,897)
Proceeds from sale of property, plant and equipment	43	681
Payment for business acquisitions, net of cash acquired	0	(5,309)
Net cash (used for) investing activities	(17,766)	(18,535)
Financing activities
Repayment of finance lease obligations	(2,292)	(3,037)
Payment of debt issuance costs	0	(1,893)
Proceeds from long-term debt	0	350,000
Repayment of long-term debt	(8,500)	(8,500)
Proceeds from short-term borrowings	250,000	0
Repayment of short-term borrowings	0	(250,000)
Proceeds from issuance of common shares under stock-based compensation plans	3,300	6,596
Payment for net settlement of stock-based awards	(41,889)	(28,721)
Dividend paid	(23,134)	(20,115)
Payment for stock repurchased and retired (including expenses related to stock repurchase)	(76,032)	(134,218)
Net cash (used for)/ provided by financing activities	101,453	(89,888)
Effect of exchange rate changes	(7,104)	(5,171)
Net decrease in cash and cash equivalents	(30,594)	(31,267)
Cash and cash equivalents at the beginning of the period	899,458	680,440	$ 680,440
Cash and cash equivalents at the end of the period	861,760	644,002	$ 899,458
Supplementary information
Cash paid during the period for interest	1,893	4,086
Cash paid during the period for income taxes, net of refund	$ 28,580	$ 21,988