Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net (loss) income	$ (67,657)	$ (51,013)	$ 10,733
Adjustments to reconcile net (loss) income to net cash (used in) provided by operating activities:
Stock-based compensation expense	5,209	4,142	2,457
Depreciation and amortization	1,497	1,121	2,078
Paid in-kind interest		(13)	765
Non-cash interest expense	302	247	38
Deferred income tax	(1,548)	(11,435)	1,811
Intangible impairment charge	23,200
Change in fair value of contingent consideration liability	(5,800)	2,600	(4,600)
Other		10	(296)
Changes in assets and liabilities:
Accounts receivable	204	892	(1,322)
Other current assets	(403)	2,046	1,314
Other assets	(150)	468	(469)
Accounts payable	(2,906)	2,779	243
Accrued expenses	1,009	(6,274)	6,581
Other current liabilities			(158)
Other liabilities	291	323	343
Net cash (used in) provided by operating activities	(46,752)	(54,107)	19,518
Cash flows from investing activities:
Purchases of property and equipment	(817)	(269)	(4,286)
Proceeds from sale of fixed assets		37	347
Net cash used in investing activities	(817)	(232)	(3,939)
Cash flows from financing activities:
Net proceeds common stock	70,000
Net proceeds from issuance of long-term debt			48,650
Proceeds from exercise of stock options	467	469	1,340
Repayment of debt	(5,390)
Return of estimated interest payment for noncontrolling interest		15	(368)
Net cash provided by financing activities	94,717	5,510	49,622
Effect of currency rate changes on cash, cash equivalents and restricted cash	(92)	83	(86)
Net (decrease) increase in cash, cash equivalents and restricted cash	47,056	(48,746)	65,115
Cash, cash equivalents and restricted cash at beginning of period	92,164	140,910	75,795
Cash, cash equivalents and restricted cash at end of period	139,220	92,164	140,910
Supplemental disclosure of cash flow information
Cash paid for interest	4,660	4,821
Noncash financing activity
Subscription receivable	(2,109)	2,109
Cash, cash equivalents and restricted cash information
Cash and cash equivalents at beginning of period	90,642
Restricted cash included in long-term assets at the beginning of period	1,522
Cash, cash equivalents and restricted cash at beginning of period	92,164	140,910	75,795
Cash and cash equivalents at end of period	137,686	90,642
Restricted cash included in long-term assets at the end of period	1,534	1,522
Cash, cash equivalents and restricted cash at end of period	139,220	92,164	140,910
Public Offering [Member]
Cash flows from financing activities:
Net proceeds common stock	69,987
At-the-market Offering [Member]
Cash flows from financing activities:
Net proceeds common stock	$ 29,653	$ 5,026