CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net loss	$ (94,187)	$ (45,589)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	921	221
Stock-based compensation expense	15,099	10,130
Change in fair value of contingent consideration	866
Changes in operating assets and liabilities:
Accounts receivable	(552)
Inventory	(1,044)
Prepaid expenses and other assets	(3,461)	(4,331)
Accounts payable	5,932	3,130
Accrued expenses	2,863	(14)
Net cash used in operating activities	(73,563)	(36,453)
Cash flows from investing activities:
Purchases of property and equipment	(1,210)	(658)
Acquisition of Confluence, net of cash acquired		(9,647)
Purchases of marketable securities	(112,344)	(120,496)
Proceeds from sales and maturities of marketable securities	193,427	96,674
Net cash provided by (used in) investing activities	79,873	(34,127)
Cash flows from financing activities:
Capital lease payments	(499)
Proceeds from the exercise of employee stock options	577	235
Net cash provided by financing activities	78	100,464
Net increase in cash and cash equivalents	6,388	29,884
Cash and cash equivalents at beginning of period	20,202	30,171
Cash and cash equivalents at end of period	26,590	60,055
Supplemental disclosures of non-cash investing and financing activities:
Additions to property and equipment included in accounts payable	102	20
Fair value of stock issued in connection with Confluence acquisition		9,675
Property and equipment obtained pursuant to capital lease financing arrangements	2,076
Offering costs included in accounts payable	$ 20	107
At The Market Offering
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs		19,311
Public Offering August 2017
Cash flows from financing activities:
Proceeds from issuance of common stock, net of issuance costs		$ 80,918