Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 81,698	$ 194,494
Marketable securities		34,982
Accounts receivable, net	9,670
Inventory	2,029
Prepaid expenses and other, current	12,997	6,998
Total current assets	106,394	236,474
Property and equipment, net	4,470	5,153
Prepaid expenses and other, long-term	1,989	6,846
Intangible assets, net	48,355
Restricted cash	4,317	4,317
Total assets	165,525	252,790
Current liabilities:
Accounts payable	27,692	20,035
Accrued expenses	30,648	17,426
Total current liabilities	58,340	37,461
Deferred rent	5,406	5,505
Long term debt	48,477
Total liabilities	112,223	42,966
Commitments and contingencies (Note 11)
Stockholders' equity:
Common stock - $.0001 par value; 100,000,000 shares authorized; 37,594,851 shares issued and outstanding at December 31, 2017 and 36,826,010 issued and outstanding at December 31, 2016	4	4
Additional paid-in capital	1,142,213	1,006,344
Receivable from exercise of stock options	(449)
Accumulated other comprehensive loss		(13)
Accumulated deficit	(1,088,466)	(796,511)
Total stockholders' equity	53,302	209,824
Total liabilities and stockholders' equity	$ 165,525	$ 252,790

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

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.