Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flow from operating activities
Net loss	$ (31,023)	$ (65,757)
Adjustments to reconcile net loss to net cash provided by operating activities:
Stock-based compensation expense	12,120	13,072
Depreciation	2,007	1,538
Amortization of premiums and discounts on marketable securities	(2,927)	(1,563)
In-kind research and development expenses	616	176
Other non-cash items	(1,810)	497
Changes in operating assets and liabilities:
Collaboration receivable	(11,733)
Unbilled accounts receivable	(2,300)
Prepaid expenses and other current assets	52	(127)
Operating lease, right-of-use asset	2,092
Other non-current assets	(413)	(180)
Accounts payable	2,988	402
Accrued expenses	6,244	(3,306)
Operating lease liabilities	(1,860)
Lease incentive benefit		321
Deferred revenue	97,973	63,388
Net cash provided by operating activities	72,026	8,461
Cash flow from investing activities
Purchases of property and equipment	(4,342)	(3,782)
Proceeds from sale of equipment	171
Purchases of marketable securities	(409,068)	(274,381)
Proceeds from maturities of marketable securities	296,300	276,000
Net cash used in investing activities	(116,939)	(2,163)
Cash flow from financing activities
Proceeds from the exercise of stock options	2,606	3,472
Proceeds from the issuance of common stock in connection with the Neurocrine Collaboration Agreement, net	77,617
Proceeds from the purchase of common stock under ESPP	471	842
Net cash provided by financing activities	80,694	4,314
Net increase in cash, cash equivalents, and restricted cash	35,781	10,612
Cash, cash equivalents, and restricted cash beginning of period	47,594	32,265
Cash, cash equivalents, and restricted cash end of period	83,375	42,877
Supplemental disclosure of cash and non-cash activities
Capital expenditures incurred but not yet paid	$ 357
ASU 2014-09
Supplemental disclosure of cash and non-cash activities
Impact of adopting new accounting standards		$ 20,050