Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 45,701	$ 87,229
Marketable securities	125,811	171,555
Accounts receivable, net	22,589	13,121
Inventories	12,870	7,637
Prepaid expenses and other current assets	4,213	5,500
Total current assets	211,184	285,042
Property and equipment, net	9,753	10,710
Long-term investments	5,050
Right-of-use assets	6,493
Total assets	232,480	295,752
Current liabilities
Accounts payable	11,084	12,340
Accrued expenses and other current liabilities	14,739	14,310
Operating lease liabilities	1,247
Current portion of long-term debt		9,967
Total current liabilities	27,070	36,617
Long-term operating lease liability, net	5,686
Long-term debt, net	8,956	3,640
2024 convertible notes, net	149,046	144,879
Other long-term liabilities	251	537
Total liabilities	191,009	185,673
Commitments and contingencies
Preferred stock, $0.001 par value; 10,000,000 shares authorized at June 30, 2019 and December 31, 2018 and 0 shares issued and outstanding at June 30, 2019 and December 31, 2018	0	0
Stockholders' equity
Common stock, $0.001 par value; 100,000,000 shares authorized; 38,106,641 and 37,946,341 shares issued and outstanding, at June 30, 2019 and December 31, 2018, respectively	38	38
Additional paid-in capital	638,054	628,944
Accumulated other comprehensive income (loss)	230	(77)
Accumulated deficit	(596,851)	(518,826)
Total stockholders' equity	41,471	110,079
Total liabilities and stockholders' equity	$ 232,480	$ 295,752