Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 199,980	$ 242,425
Short-term investments	56,678	37,133
Accounts receivable-net of allowance for doubtful accounts of $728 and $459 at March 31, 2014 and December 31, 2013, respectively	23,239	28,402
Prepaid expenses and other current assets	10,201	4,315
Total current assets	290,098	312,275
Property and equipment, net	15,188	9,790
Purchased intangible assets, net	2,599
Goodwill	8,966
Other assets	5,236	1,866
Total assets	322,087	323,931
Current liabilities:
Current portion of notes payable	1,816	2,727
Accounts payable	2,662	3,174
Accrued expenses	16,194	17,362
Deferred revenue	19,961	19,609
Deferred rent	193	184
Total current liabilities	40,826	43,056
Long-term liabilities:
Deferred revenue	19,630	18,862
Notes payable	918	1,524
Deferred rent	849	884
Total liabilities	62,223	64,326
Stockholders' equity:
Preferred stock, $0.01 par value per share-10,000 shares authorized
Common stock, $0.01 par value per share-240,000 shares authorized, 34,597 and 34,268 shares issued and outstanding at March 31, 2014 and December 31, 2013, respectively	346	343
Additional paid-in capital	365,778	356,766
Accumulated other comprehensive gain	67	64
Accumulated deficit	(106,327)	(97,568)
Total stockholders' equity	259,864	259,605
Total liabilities and stockholders' equity	$ 322,087	$ 323,931