Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flow from operating activities:
Net loss	$ (25,800)	$ (35,202)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	6,394	4,223
Depreciation and amortization	357	191
Noncash lease expense	339
Net accretion and amortization of investments in marketable securities	(215)	(1,703)
Change in fair value of warrant liabilities	(162)	303
Acquired in-process research and development expense	1,500	0
Change in fair value of contingent consideration	(7,900)	3,000
Changes in operating assets and liabilities:
Accounts receivable	0	(15,500)
Other receivable	(19,741)	0
Prepaid expenses, escrow holdback and other current assets	(722)	5,270
Other assets	(405)
Accounts payable, accrued and other liabilities	(4,435)	(7,096)
Operating lease liability	(452)
Deferred revenue	(1,249)	15,500
Net cash used in operating activities	(52,491)
Cash flows from investing activities:
Cash paid for in-process research and development asset	(1,500)	0
Purchases of marketable securities	(15,695)	(145,826)
Proceeds from maturities of marketable securities	54,605	171,225
Purchases of property and equipment	(193)	(4,535)
Net cash provided by investing activities	37,217	20,864
Cash flows from financing activities:
Payment of contingent consideration	0	(10,000)
Proceeds from issuance of common stock under equity incentive plans	2,040	4,379
Taxes paid related to net share settlement of equity awards	(569)	(582)
Proceeds from issuance of common stock, net of issuance costs	221,708	0
Net cash provided by (used in) financing activities	223,179	(6,203)
Net decrease in cash and cash equivalents	207,905	(10,166)
Cash and cash equivalents, beginning of the period	62,070	68,454
Cash and cash equivalents, end of the period	$ 269,975	$ 58,288