CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	[1]
Current assets:
Cash and cash equivalents	$ 657,615	$ 521,439
Marketable securities-available-for-sale	153,054	186,344
Restricted cash and investments	517	516
Accounts receivable	101,280	114,450
Inventory	1,309	1,783
Prepaid expenses and other current assets	21,806	17,843
Total current assets	935,581	842,375
Restricted cash and investments	13,866	13,977
Long term investment	32,298	35,248
Inventory	17,277	17,555
Property and equipment, net	92,622	86,006
Other assets, net	12,298	12,279
Total assets	1,103,942	1,007,440
Current liabilities:
Accounts payable	31,899	30,085
Accrued compensation	23,197	38,117
Interest payable	2,285	762
Accrued and other current liabilities	133,641	86,531
Deferred revenue-collaborative agreements	9,297	12,512
Total current liabilities	200,319	168,007
Convertible senior notes	627,642	619,893
Other liabilities	48,233	48,385
Total liabilities	$ 876,194	$ 836,285
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; none issued or outstanding as of March 31, 2016 and December 31, 2015
Common stock, $0.001 par value; 400,000,000 shares authorized; 187,402,129 and 186,650,249 shares issued and outstanding as of March 31, 2016 and December 31, 2015, respectively	$ 187	$ 187
Additional paid-in capital	1,982,104	1,950,764
Accumulated other comprehensive income (loss)	397	(809)
Accumulated deficit	(1,754,940)	(1,778,987)
Total stockholders' equity (deficit)	227,748	171,155
Total liabilities and stockholders' equity (deficit)	$ 1,103,942	$ 1,007,440

[1] The condensed consolidated balance sheet at December 31, 2015 has been derived from the audited financial statements at that date.