Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019
Operating activities
Net loss		$ (1,420)	$ (27,099)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation		9,953	5,600
Depreciation of property and equipment		275	276
Amortization of right-of-use assets		695	523
Non-cash interest expense (income), net		424	(1,061)
Changes in assets and liabilities:
Accounts receivable, other		20	0
Accounts receivable due from related party		(72)	2,058
Prepaids and other current assets		(388)	(340)
Other assets		254	117
Accounts payable		370	8
Other liabilities		(809)	29
Deferred revenue from related party		(55,066)	(13,272)
Net cash used in operating activities		(45,764)	(33,161)
Investing activities
Purchases of property and equipment, net		(2,130)	(236)
Purchases of investments		(100,708)	(154,889)
Sales of investments		0	4,967
Maturities of investments		91,830	116,270
Net cash used in investing activities		(11,008)	(33,888)
Financing activities
Proceeds from issuance of common stock		325,654	73,276
Proceeds from exercise of stock options and employee stock purchase plan		24,495	5,604
Employees' tax withheld and paid for restricted stock units		(3,709)	(1,174)
Borrowings under credit facility agreement, net of issuance costs		4,358	0
Net cash provided by financing activities		350,798	77,706
Net increase in cash, cash equivalents and restricted cash		294,026	10,657
Cash, cash equivalents and restricted cash at beginning of period		40,259	28,088
Cash, cash equivalents and restricted cash at end of period		334,285	38,745
Supplemental disclosures of cash flow information
Cash paid for interest		913	871
Right-of-use assets obtained in exchange for lease obligations	[1]	27,078	2,796
Purchases of property and equipment, net recorded in accounts payable and accrued liabilities		$ 1,560	$ 0

[1] Amount for the six months ended June 30, 2019 includes the transition adjustment of $1,301 for the adoption of Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842).