CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (142,760)	$ (94,187)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,089	921
Stock-based compensation expense	12,996	15,099
Change in fair value of contingent consideration	734	866
Goodwill impairment charge	18,504
Intangible asset impairment charge	27,638
Changes in operating assets and liabilities:
Accounts receivable	(13,003)	(552)
Inventory	602	(1,044)
Prepaid expenses and other assets	3,278	(3,461)
Accounts payable	3,050	5,932
Accrued expenses	6,817	2,863
Net cash used in operating activities	(76,055)	(73,563)
Cash flows from investing activities:
Purchases of property and equipment	(1,347)	(1,210)
Purchases of marketable securities	(121,303)	(112,344)
Proceeds from sales and maturities of marketable securities	171,891	193,427
Net cash provided by investing activities	49,241	79,873
Cash flows from financing activities:
Finance lease payments	(392)	(499)
Proceeds from the exercise of employee stock options	85	577
Net cash (used in) provided by financing activities	(307)	78
Net increase (decrease) in cash and cash equivalents	(27,121)	6,388
Cash and cash equivalents at beginning of period	57,019	20,202
Cash and cash equivalents at end of period	29,898	26,590
Supplemental disclosure of non-cash investing and financing activities:
Additions to property and equipment included in accounts payable	$ 207	102
Property and equipment obtained pursuant to capital lease financing arrangements		2,076
Offering costs included in accounts payable		$ 20