Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ 2,314	$ (2,796)
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Bargain purchase gain	(6,988)
Depreciation and amortization	511	97
Stock-based compensation	86	124
Amortization of discount on short-term investments		5
Loss (gain) on revaluation of financial instruments	3	(181)
Noncash interest expense	323	651
Amortization of note discount	18	36
Noncash interest expense related to sale of future royalties	298
Change in operating assets and liabilities:
Accounts receivable, net of allowance	1,947	(770)
Prepaid expenses and other assets	(469)	(187)
Accounts payable	(3,097)	(1,424)
Accrued liabilities	(5,536)	169
Net cash used in operating activities	(10,590)	(4,276)
Cash flows from investing activities:
Purchase of property and equipment	(140)	(79)
Cash acquired in reverse merger	25,525
Cash paid for fractional shares in merger	(21)
Purchases of short-term investments	(573)	(4,430)
Proceeds from maturities of short-term investments	1,988	3,665
Net cash provided by (used in) investing activities	26,779	(844)
Cash flows from financing activities:
Repayment of principal on secured promissory note payable to Oxford Finance	(278)
Proceeds from issuance of common stock upon exercise of stock options	13
Net cash used in financing activities	(265)
Net increase (decrease) in cash and cash equivalents	15,924	(5,120)
Cash and cash equivalents at beginning of the period	1,571	8,405
Cash and cash equivalents at end of the period	17,495	3,285
Supplemental disclosure of cash flow information:
Interest paid	95	57
Supplemental disclosure of non-cash financing activity:
Issuance of common stock upon reverse merger, net of cash paid for partial shares	31,768
Conversion of convertible promissory notes, related parties into common stock upon reverse merger	35,577
Reclassification of convertible preferred stock warrant liability to equity	70
Acquisition of property and equipment included in accounts payable	$ 72