Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 198,565	$ 159,678
Marketable securities	171,267	313,661
Prepaid expenses and other current assets	3,661	6,969
Total current assets	373,493	480,308
Property and equipment, net	4,057	1,897
Other assets	551	260
Total assets	378,101	482,465
Current liabilities:
Accounts payable	2,665	6,228
Accrued expenses and other current liabilities	22,642	14,952
Total current liabilities	25,307	21,180
Other non-current liabilities	402	0
Total liabilities	25,709	21,180
Commitments and contingencies
Stockholders’ equity:
Common stock, $.0001 par value; 200,000,000 shares authorized, 43,109,927 shares and 42,984,243 shares issued and outstanding at September 30, 2016 and December 31, 2015, respectively	4	4
Additional paid-in-capital	928,184	907,040
Accumulated other comprehensive income	52	5
Accumulated deficit	(575,848)	(445,764)
Total stockholders’ equity	352,392	461,285
Total liabilities and stockholders’ equity	$ 378,101	$ 482,465

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).