CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 217,791	$ 216,226
Marketable securities	36,531	29,414
Accounts receivable, net of allowance for doubtful accounts of $900 and $763 as of March 31, 2016 and December 31, 2015, respectively	24,094	26,168
Prepaid expenses and other current assets	11,984	11,423
Total current assets	290,400	283,231
Marketable securities, noncurrent	18,387	22,336
Property and equipment, net	55,543	56,540
Goodwill and intangible assets, net	56,746	57,050
Other assets	4,606	3,529
Total assets	425,682	422,686
Current liabilities:
Accounts payable	6,497	9,332
Accrued liabilities	11,626	9,742
Accrued compensation and related benefits	15,193	14,115
Deferred revenue	90,551	84,210
Total current liabilities	123,867	117,399
Deferred revenue, noncurrent	1,434	1,405
Other liabilities	10,530	10,592
Total liabilities	$ 135,831	$ 129,396
Commitments and contingencies (Note 7)
Stockholders’ equity:
Preferred stock
Common stock	$ 917	$ 905
Additional paid-in capital	531,431	511,183
Accumulated other comprehensive income (loss)	1,247	(2,225)
Accumulated deficit	(243,092)	(215,921)
Treasury stock at cost (0.5 million shares as of March 31, 2016 and December 31, 2015)	(652)	(652)
Total stockholders’ equity	289,851	293,290
Total liabilities and stockholders’ equity	$ 425,682	$ 422,686