Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current Assets:
Cash and cash equivalents	$ 52,151	$ 41,135
Marketable securities	210,441	265,744
Accounts receivable, net	5,621	4,933
Inventory, net	8,157	6,677
Prepaid expenses and other current assets	7,722	7,375
Total current assets	284,092	325,864
Property and Equipment, at cost:
Computer equipment and computer software	15,827	14,025
Laboratory equipment	13,496	12,786
Leasehold improvements	10,757	7,118
Buildings	4,792	4,777
Assets under construction	4,735	8,038
Furniture and fixtures	1,825	1,265
Property and Equipment, gross	51,432	48,009
Less-Accumulated depreciation	(16,386)	(13,913)
Net property and equipment	35,046	34,096
Other long-term assets	4,650	4,070
Total assets	323,788	364,030
Current Liabilities:
Accounts payable	2,841	3,308
Accrued liabilities	20,477	22,253
Debt and capital lease obligation, current portion	169	166
Other short-term liabilities	1,191	996
Total current liabilities	24,678	26,723
Long-term debt	4,750	4,789
Other long-term liabilities	4,893	4,601
Lease incentive obligation, less current portion	1,134	1,061
Total liabilities	$ 35,455	$ 37,174
Commitments and contingencies
Stockholders' Equity:
Preferred stock, $0.01 par value Authorized—5,000,000 shares issued and outstanding—no shares at March 31, 2016 and December 31, 2015
Common stock, $0.01 par value Authorized—200,000,000 shares issued and outstanding—97,737,710 and 96,674,786 shares at March 31, 2016 and December 31, 2015	$ 978	$ 968
Additional paid-in capital	913,455	904,931
Accumulated other comprehensive loss	(17)	(433)
Accumulated deficit	(626,083)	(578,610)
Total stockholders' equity	288,333	326,856
Total liabilities and stockholders’ equity	$ 323,788	$ 364,030