Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flow from operating activities
Net income (loss)	$ 36,741	$ (43,597)	$ (88,288)
Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities:
Stock-based compensation expense	14,934	15,640	15,710
Depreciation	3,817	2,765	2,117
Amortization of premiums and discounts on marketable securities	27	(3,584)	(2,163)
In-kind research and development expenses		616	176
Deferred rent			52
Change in fair value for common stock and warrants to purchase equity securities	(7,698)	(1,612)	807
Changes in operating assets and liabilities:
Related party collaboration receivable	10,484	(18,496)
Prepaid expenses and other current assets	(551)	1,675	(3,937)
Operating lease, right-of-use assets	(7,592)	2,951
Other non-current assets	275	(343)	(180)
Accounts payable	(3,436)	2,598	(282)
Accrued expenses	(6,480)	11,728	(1,600)
Operating lease liabilities	13,439	(2,506)
Lease incentive benefit			321
Deferred revenue	(150,676)	80,831	61,380
Net cash (used in) provided by operating activities	(96,716)	48,666	(15,887)
Cash flow from investing activities
Purchases of property and equipment	(12,097)	(7,718)	(4,305)
Proceeds from sale of equipment		172
Purchases of marketable securities	(70,403)	(494,231)	(333,228)
Proceeds from maturities of marketable securities	195,495	411,300	364,000
Net cash provided by (used in) investing activities	112,995	(90,477)	26,467
Cash flow from financing activities
Proceeds from the issuance of common stock in connection with the Neurocrine Collaboration Agreement, net		77,617
Proceeds from the exercise of stock options	2,319	2,714	3,889
Proceeds from the purchase of common stock under ESPP	844	663	860
Net cash provided by financing activities	3,163	80,994	4,749
Net increase in cash and cash equivalents	19,442	39,183	15,329
Cash, cash equivalents, and restricted cash beginning of period	86,777	47,594	32,265
Cash, cash equivalents, and restricted cash end of period	106,219	86,777	47,594
Supplemental disclosure of cash and non-cash activities
Impact of adopting new accounting standards			(20,050)
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	10,818	30,964
Capital expenditures incurred but not yet paid	$ 831	$ 434	$ 300