Condensed Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 159,678	$ 28,518
Marketable Securities	313,661	76,758
Prepaid expenses and other current assets	6,969	2,057
Total current assets	480,308	107,333
Property and equipment, net	1,897	842
Other assets	260	242
Total assets	482,465	108,417
Current liabilities:
Accounts payable	6,228	2,292
Accrued expenses and other current liabilities	14,952	18,267
Total current liabilities	21,180	20,559
Note payable, net of current portion and discount		24,394
Total liabilities	$ 21,180	$ 44,953
Commitments and contingencies
Stockholders' equity:
Common stock, $.0001 par value; 200,000,000 shares authorized, 42,984,243 shares and 32,924,535 shares issued and outstanding at December 31, 2015 and 2014, respectively	$ 4	$ 3
Additional paid-in-capital	907,040	407,720
Accumulated other comprehensive income (loss)	5	(21)
Accumulated deficit	(445,764)	(344,238)
Total stockholders' equity	461,285	63,464
Total liabilities and stockholders' equity	$ 482,465	$ 108,417

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).