Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net income (loss)	$ 127,840	$ (111,250)	$ (94,733)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities
Stock-based compensation expense	38,808	31,949	26,854
Depreciation and amortization	9,564	8,407	7,152
Provision for credit losses (recoveries)	(2,569)	7,678	0
Net amortization of premiums (accretion of discounts) on marketable debt securities	5,842	1,083	(1,196)
Net gains on investments	(5,189)	(4,918)	(37,774)
Imputed interest income from licensing	(360)	(2,163)	(2,951)
Non-cash interest expense	4,642	771
Other non-cash adjustments	79	163	268
Changes in operating assets and liabilities
Accounts receivable	14,118	(9,898)	(8,622)
Prepaid expenses	(8,247)	(4,030)	(973)
Other current assets	(7,314)	2,341	(499)
Operating lease right-of-use assets	4,866	3,219	2,431
Other assets	(2,272)	399	(2,694)
Accounts payable	(2,304)	3,873	1,528
Accrued expenses and other current liabilities	29,908	17,400	6,882
Deferred revenue	(899)		(600)
Operating lease liabilities	12,073	2,139	(2,255)
Other liabilities	289	(1,224)	(523)
Net cash provided by (used in) operating activities	218,875	(54,061)	(107,705)
Cash flows from investing activities
Purchases of marketable debt securities	(498,144)	(123,041)	(190,735)
Maturities of marketable debt securities	170,086	233,468	289,994
Sales of marketable debt securities		2,287
Sales of equity securities	5,591	36,914	6,020
Purchases of property and equipment	(84,175)	(26,869)	(11,720)
Net cash provided by (used in) investing activities	(406,642)	122,759	93,559
Cash flows from financing activities
Proceeds from exercise of stock options	4,281	5,623	7,062
Taxes paid related to net settlement of stock options	(2)
Proceeds from issuance of common stock under employee stock purchase plan	1,768	1,799	1,314
Proceeds from public offering of common stock, net of underwriting discounts and commissions	216,438
Issuance costs for public offering of common stock	(379)
Proceeds from sale of future royalties		196,000
Repayments under liability related to sale of future royalties, net of imputed interest	(26,591)
Transaction costs for sale of future royalties	(265)	(3,208)
Net cash provided by financing activities	195,250	200,214	8,376
Net increase (decrease) in cash and cash equivalents and restricted cash	7,483	268,912	(5,770)
Cash and cash equivalents and restricted cash
Beginning of period	339,756	70,844	76,614
End of period	347,239	339,756	70,844
Supplemental cash flow information
Cash paid (received) for income taxes	5,996	(191)	904
Cash paid for imputed interest under liability related to sale of future royalties	21,635
Supplemental disclosures of non-cash investing and financing activities
Increase in accounts payable and accrued liabilities related to purchases of property and equipment	558	6,812	$ 1,572
Non-cash additions to property and equipment through tenant improvement allowance		2,263
Non-cash consideration received for licenses granted		1,123
Transaction costs for sale of future royalties in accounts payable and other current liabilities		$ 265
Proceeds due to Company from sales of non-marketable equity securities	$ 600