Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities
Net loss	$ (14,577)	$ (3,675)	$ (2,024)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization of property, equipment and software	2,655	1,971	1,658
Amortization of intangible assets	2,501	2,440	1,926
Loss on disposal of assets	68	8	3
Impairment of long-lived assets	100
Stock-based compensation	14,915	12,802	12,892
Adjustments to fair value of contingent consideration	1,941	548
Provision for doubtful accounts	408	118	265
Deferred income taxes	9,789	(835)	(1,631)
Excess tax benefit from equity awards	(34)	(883)	(5,048)
Payments of contingent consideration for business acquisitions in excess of fair value on acquisition date	(147)
Changes in operating assets and liabilities:
Accounts receivable	(3,081)	(1,730)	(3,642)
Prepaid expenses and other current assets	1,910	(1,270)	1,621
Other assets	(230)	4	(93)
Accounts payable	66	(760)	616
Accrued compensation	337	609	75
Accrued expenses	2,173	899	4,814
Deferred revenue	6,523	7,043	4,624
Other liabilities	5,827	441	23
Net cash provided by operating activities	31,144	17,730	16,079
Cash flows from investing activities
Business acquisitions, net of cash acquired	(6,947)	(9,851)
Purchases of property, equipment and software	(13,758)	(2,602)	(1,445)
Software development costs	(305)	(446)	(156)
Proceeds from disposal of assets	14	5
Purchases of available-for-sale securities	(22,907)	(10,034)	(32,332)
Maturities of available-for-sale securities	18,390	23,379	35,183
Net cash provided by (used in) investing activities	(25,513)	451	1,250
Cash flows from financing activities
Repurchases of common stock	(20,006)	(13,503)	(4,131)
Proceeds from exercises of stock options	18,952	4,163	2,403
Excess tax benefit from equity awards	34	883	5,048
Payments of contingent consideration for business acquisitions	(1,289)
Proceeds from notes payable	440
Payments on notes payable and capital lease obligations	(177)	(317)	(218)
Net cash provided by (used in) financing activities	(2,046)	(8,774)	3,102
Effect of exchange rate changes on cash and cash equivalents	(219)	(306)	(43)
Net increase in cash and cash equivalents	3,366	9,101	20,388
Cash and cash equivalents at beginning of year	94,918	85,817	65,429
Cash and cash equivalents at end of year	98,284	94,918	85,817
Supplemental disclosure of cash flow information:
Cash paid for interest	22	39	31
Cash paid for income taxes, net of refunds	(251)	1,126	101
Supplemental disclosure of non-cash investing and financing activities:
Assets acquired under capital leases and other financing arrangements	$ 440	$ 11	$ 90