Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets
Cash and cash equivalents	$ 82,400	$ 67,775
Marketable securities	14,934	25,732
Accounts receivable, net of allowance for doubtful accounts	69	92
Prepaid expenses and other current assets	9,644	6,513
Total current assets	107,047	100,112
Property and equipment, net	40,008	39,653
Restricted cash	1,300	750
Goodwill	95,505	95,505
Acquired intangible assets, net	6,198	6,758
Deferred taxes	13,570	11,377
Other assets	2,950	3,107
Total assets	266,578	257,262
Current liabilities
Accounts payable	6,867	8,167
Accrued expenses	16,163	10,803
Deferred revenue	34,801	32,700
Total current liabilities	57,831	51,670
Other long-term liabilities	2,070	2,010
Total liabilities	59,901	53,680
Commitments and contingencies (Note 8)
Stockholders' equity
Preferred stock; $0.01 par value; 5,000,000 shares authorized; no shares issued or outstanding at March 31, 2013 and December 31, 2012
Common stock; $0.01 par value; 100,000,000 shares authorized; 30,699,266 and 30,651,375 shares issued and outstanding at March 31, 2013 and December 31, 2012, respectively	307	307
Additional paid-in capital	213,597	209,987
Accumulated other comprehensive income	10	11
Accumulated deficit	(7,237)	(6,723)
Total stockholders' equity	206,677	203,582
Total liabilities and stockholders' equity	$ 266,578	$ 257,262