Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 174,621	$ 258,567
Restricted cash	47	47
Marketable securities	107,486	73,880
Prepaid expenses and other current assets	6,548	2,315
Total current assets	288,702	334,809
Property and equipment, net	6,106	4,922
Other assets	551	551
Total assets	295,359	340,282
Current liabilities:
Accounts payable	6,727	6,128
Accrued expenses and other current liabilities	26,277	26,597
Total current liabilities	33,004	32,725
Other non-current liabilities	260	379
Total liabilities	33,264	33,104
Commitments and contingencies
Stockholders’ equity:
Common stock, $.0001 par value; 200,000,000 shares authorized, 43,245,804 shares and 43,141,134 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	4	4
Additional paid-in-capital	947,042	935,671
Accumulated other comprehensive income	34	71
Accumulated deficit	(684,985)	(628,568)
Total stockholders’ equity	262,095	307,178
Total liabilities and stockholders’ equity	$ 295,359	$ 340,282

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).