Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 175,311	$ 254,712
Short-term investments, available for sale	285,168	261,217
Accounts receivable, net	44,624	31,127
Other current assets	8,613	7,863
Total current assets	513,716	554,919
Property and equipment, net	11,825	10,811
Long-term investments, available for sale	276,319	247,361
Restricted cash	4,500	4,500
Total assets	806,360	817,591
Current liabilities:
Accounts payable and accrued liabilities	45,650	53,520
Current portion of cease-use liability		62
Current portion of deferred gain on sale of real estate	731	731
Other current liabilities	85	113
Total current liabilities	46,466	54,426
Deferred gain on sale of real estate	7,860	8,043
Deferred revenue	10,231	10,231
Deferred rent	3,107	3,135
Convertible senior notes	374,209	369,618
Total liabilities	441,873	445,453
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $0.001 par value; 220,000,000 shares authorized; issued and outstanding shares were 89,882,062 as of March 31, 2018 and 88,793,903 as of December 31, 2017	90	89
Additional paid-in capital	1,608,778	1,572,765
Accumulated other comprehensive loss	(3,697)	(1,850)
Accumulated deficit	(1,240,684)	(1,198,866)
Total stockholders’ equity	364,487	372,138
Total liabilities and stockholders’ equity	$ 806,360	$ 817,591