Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 219,658	$ 185,543	$ 122,856
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	14,474	14,445	16,880
Provision for doubtful debts/advances	272	1,101	97
Realized gains on sales of short-term investments	(3,600)	(3,012)	(2,539)
Deferred income taxes	(5,827)	(1,343)	(4,613)
Compensation expense related to restricted stock	4,732	3,725	2,684
Uncertain tax positions and other tax credits	0	0	(3,948)
Gain on sale of property and equipment	0	(977)	0
Changes in assets and liabilities:
Accounts receivable and revenue earned in excess of billings	(41,783)	(10,065)	(40,907)
Other current assets	(16,834)	(15,751)	(9,183)
Accrued payroll and other liabilities	28,698	19,742	27,399
Deferred revenues	176	(4,720)	326
Net cash provided by operating activities	199,966	188,688	109,052
Cash flows from investing activities:
Property and equipment expenditures	(20,495)	(32,255)	(38,232)
Proceeds from sale of property and equipment	46	1,445	0
Purchases of mutual funds	(294,010)	(270,685)	(213,829)
Purchases of term deposits with banks	(395,589)	(277,116)	(206,201)
Proceeds from sales of mutual funds	200,836	238,604	219,032
Maturities of term deposits with banks	288,719	194,873	159,566
Net cash used in investing activities	(220,493)	(145,134)	(79,664)
Cash flows from financing activities:
Net proceeds from issuance of common stock	0	0	2
Excess tax benefits on stock-based compensation plans	656	645	0
Repayment of loans and borrowings	(54,500)	0	0
Proceeds from loans and borrowings	150,000	50,000	0
Interest on loans and borrowings	0	29	0
Dividends paid	0	(106,231)	(9,992)
Net cash provided by (used in) financing activities	96,156	(55,557)	(9,990)
Effect of foreign currency exchange rate changes on cash	8,506	1,997	6,725
Change in cash and cash equivalents	84,135	(10,006)	26,123
Cash and cash equivalents, beginning of year	94,622	104,628	78,505
Cash and cash equivalents, end of year	178,757	94,622	104,628
Non cash investing and financing activities
Cash dividends declared but unpaid	0	0	2,494
Cash paid for income taxes	62,967	48,596	28,610
Cash paid for interest	$ 1,601	$ 0	$ 0