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	$ 13,024	$ 26,296	$ 21,991
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	9,268	8,921	5,359
Amortization of intangible assets	2,230	2,445	2,562
Net (gains) losses from investments	2,433	(94)	399
Deferred income taxes	(4,529)	(10,967)	15,137
Stock-based compensation	6,051	5,397	3,642
Amortization of premium on investments	2,261	2,803	3,321
Foreign currency losses	385	405	1,290
Changes in assets and liabilities, net of acquisitions
Accounts receivable	(2,930)	6,959	(7,594)
Deferred commissions	(3,529)	2,607	589
Prepaid expenses and other current assets	607	6,610	(8,484)
Accounts payable	222	(490)	(1,898)
Accrued expenses and other liabilities	3,547	549	2,485
Deferred revenue	1,673	1,706	16,645
Net cash provided by operating activities	30,713	53,147	55,444
Cash flows from investing activities:
Acquisitions			(7,531)
Purchases of property and equipment	(3,127)	(5,103)	(39,776)
Purchases of marketable investments	(44,667)	(91,421)	(113,909)
Proceeds from sales and maturities of marketable investments	105,086	91,335	93,090
Change in restricted cash		946	14,542
Other investing activity	264	167	548
Net cash provided by (used in) investing activities	57,556	(4,076)	(53,036)
Cash flows from financing activities:
Dividends paid on common stock	(12,394)	(12,588)
Repurchases of common stock	(118,210)	(29,843)	(18,405)
Proceeds from issuance of common stock under employee equity incentive plans	17,387	11,215	11,554
Excess tax benefits from stock-based compensation	737	345	525
Payment of deferred acquisition consideration	(900)	(864)
Net cash used in financing activities	(113,380)	(31,735)	(6,326)
Effect of exchange rate changes on cash and cash equivalents	433	427	(1,962)
Net increase (decrease) in cash and cash equivalents	(24,678)	17,763	(5,880)
Cash and cash equivalents, beginning of year	98,810	81,047	86,927
Cash and cash equivalents, end of year	74,132	98,810	81,047
Supplemental disclosure of cash flow information:
Cash paid for income taxes	$ 9,358	$ 7,102	$ 5,929