Ionis Pharmaceuticals (IONS) 10-Q 1 Aug 24 2024 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2024	Jul. 26, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2024
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q2
Document Transition Report	false
Entity File Number	000-19125
Entity Registrant Name	Ionis Pharmaceuticals, Inc.
Entity Central Index Key	0000874015
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0336973
Entity Address, Address Line One	2855 Gazelle Court
Entity Address, City or Town	Carlsbad
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92010
City Area Code	760
Local Phone Number	931-9200
Title of 12(b) Security	Common Stock, $.001 Par Value
Trading Symbol	IONS
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		146,211,091

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 293,993	$ 399,266
Short-term investments	1,784,693	1,931,935
Contracts receivable	27,259	97,778
Inventories	28,723	28,425
Other current assets	194,715	184,449
Total current assets	2,329,383	2,641,853
Property, plant and equipment, net	75,902	71,043
Right-of-use assets	166,939	171,896
Deposits and other assets	118,904	105,280
Total assets	2,691,128	2,990,072
Current liabilities:
Accounts payable	9,243	26,027
Accrued compensation	35,018	67,727
Accrued liabilities	114,330	147,894
Income taxes payable	284	2,151
0.125 percent convertible senior notes, net	44,422	44,332
Current portion of deferred contract revenue	94,066	151,128
Other current liabilities	8,799	8,831
Total current liabilities	306,162	448,090
Long-term deferred contract revenue	188,701	241,184
Liability related to sale of future royalties, net	533,754	513,736
Long-term lease liabilities	166,438	170,875
Long-term obligations	41,773	41,836
Total liabilities	2,427,430	2,603,386
Stockholders' equity:
Common stock, $0.001 par value; 300,000,000 shares authorized, 146,025,246 and 144,340,526 shares issued and outstanding at June 30, 2024 (unaudited) and December 31, 2023, respectively	146	144
Additional paid-in capital	2,303,369	2,215,098
Accumulated other comprehensive loss	(34,838)	(32,645)
Accumulated deficit	(2,004,979)	(1,795,911)
Total stockholders' equity	263,698	386,686
Total liabilities and stockholders' equity	2,691,128	2,990,072
1.75 Percent Convertible Senior Notes [Member]
Current liabilities:
Convertible senior notes, net	563,647	562,285
0 Percent Convertible Senior Notes [Member]
Current liabilities:
Convertible senior notes, net	$ 626,955	$ 625,380

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2024	Dec. 31, 2023
Stockholders' equity:
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	146,025,246	144,340,526
Common stock, shares outstanding (in shares)	146,025,246	144,340,526
0.125 Percent Convertible Senior Notes [Member]
LIABILITIES AND STOCKHOLDERS' EQUITY
Interest rate on convertible senior notes	0.125%	0.125%
1.75 Percent Convertible Senior Notes [Member]
LIABILITIES AND STOCKHOLDERS' EQUITY
Interest rate on convertible senior notes	1.75%	1.75%
0 Percent Convertible Senior Notes [Member]
LIABILITIES AND STOCKHOLDERS' EQUITY
Interest rate on convertible senior notes	0%	0%

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Revenue:
Revenue	$ 225,250	$ 188,411	$ 344,748	$ 318,935
Expenses:
Cost of sales	4,164	2,537	6,314	3,880
Research, development and patent	222,064	229,927	436,280	427,740
Selling, general and administrative	65,113	46,142	117,758	91,658
Total operating expenses	291,341	278,606	560,352	523,278
Loss from operations	(66,091)	(90,195)	(215,604)	(204,343)
Other income (expense):
Investment income	25,599	20,792	51,884	39,419
Interest expense	(4,490)	(2,291)	(8,641)	(3,899)
Interest expense related to sale of future royalties	(18,296)	(17,655)	(36,254)	(33,170)
Gain (loss) on investments	(3,533)	718	(1,200)	189
Other income	610	11,183	887	11,414
Loss before income tax expense	(66,201)	(77,448)	(208,928)	(190,390)
Income tax expense	(64)	(7,842)	(140)	(19,223)
Net loss	$ (66,265)	$ (85,290)	$ (209,068)	$ (209,613)
Basic net loss per share (in dollars per share)	$ (0.45)	$ (0.6)	$ (1.43)	$ (1.47)
Diluted net loss per share (in dollars per share)	$ (0.45)	$ (0.6)	$ (1.43)	$ (1.47)
Shares used in computing basic net loss per share (in shares)	145,958	143,098	145,748	142,918
Shares used in computing diluted net loss per share (in shares)	145,958	143,098	145,748	142,918
Commercial Revenue [Member]
Revenue:
Revenue	$ 72,036	$ 77,897	$ 131,629	$ 145,664
SPINRAZA Royalties [Member]
Revenue:
Revenue	56,743	61,012	95,198	111,258
WAINUA Royalties [Member]
Revenue:
Revenue	3,781	0	4,907	0
Other Commercial Revenue [Member]
Revenue:
Revenue	11,512	16,885	31,524	34,406
Research and Development Revenue [Member]
Revenue:
Revenue	153,214	110,514	213,119	173,271
Collaborative Agreement Revenue [Member]
Revenue:
Revenue	141,524	91,013	190,870	129,347
WAINUA Joint Development Revenue [Member]
Revenue:
Revenue	$ 11,690	$ 19,501	$ 22,249	$ 43,924

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS [Abstract]
Net loss	$ (66,265)	$ (85,290)	$ (209,068)	$ (209,613)
Unrealized gains (losses) on debt securities, net of tax	150	(2,000)	(2,056)	6,393
Currency translation adjustment	(24)	70	(137)	174
Comprehensive loss	$ (66,139)	$ (87,220)	$ (211,261)	$ (203,046)

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Total
Balance at Dec. 31, 2022	$ 142	$ 2,059,850	$ (57,480)	$ (1,429,625)	$ 572,887
Balance (in shares) at Dec. 31, 2022	142,058
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ 0	0	0	(209,613)	(209,613)
Change in unrealized gains (losses), net of tax	0	0	6,393	0	6,393
Foreign currency translation	0	0	174	0	174
Issuance of common stock in connection with employee stock plans	$ 1	4,949	0	0	4,950
Issuance of common stock in connection with employee stock plans (in shares)	1,109
Stock-based compensation expense	$ 0	53,510	0	0	53,510
Balance at Jun. 30, 2023	$ 143	2,118,309	(50,913)	(1,639,238)	428,301
Balance (in shares) at Jun. 30, 2023	143,167
Balance at Mar. 31, 2023	$ 143	2,089,358	(48,983)	(1,553,948)	486,570
Balance (in shares) at Mar. 31, 2023	143,023
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ 0	0	0	(85,290)	(85,290)
Change in unrealized gains (losses), net of tax	0	0	(2,000)	0	(2,000)
Foreign currency translation	0	0	70	0	70
Issuance of common stock in connection with employee stock plans	$ 0	2,390	0	0	2,390
Issuance of common stock in connection with employee stock plans (in shares)	144
Stock-based compensation expense	$ 0	26,561	0	0	26,561
Balance at Jun. 30, 2023	$ 143	2,118,309	(50,913)	(1,639,238)	428,301
Balance (in shares) at Jun. 30, 2023	143,167
Balance at Dec. 31, 2023	$ 144	2,215,098	(32,645)	(1,795,911)	386,686
Balance (in shares) at Dec. 31, 2023	144,341
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ 0	0	0	(209,068)	(209,068)
Change in unrealized gains (losses), net of tax	0	0	(2,056)	0	(2,056)
Foreign currency translation	0	0	(137)	0	(137)
Issuance of common stock in connection with employee stock plans	$ 2	26,203	0	0	26,205
Issuance of common stock in connection with employee stock plans (in shares)	1,684
Stock-based compensation expense	$ 0	62,068	0	0	62,068
Balance at Jun. 30, 2024	$ 146	2,303,369	(34,838)	(2,004,979)	263,698
Balance (in shares) at Jun. 30, 2024	146,025
Balance at Mar. 31, 2024	$ 146	2,270,047	(34,964)	(1,938,714)	296,515
Balance (in shares) at Mar. 31, 2024	145,845
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ 0	0	0	(66,265)	(66,265)
Change in unrealized gains (losses), net of tax	0	0	150	0	150
Foreign currency translation	0	0	(24)	0	(24)
Issuance of common stock in connection with employee stock plans	$ 0	2,594	0	0	2,594
Issuance of common stock in connection with employee stock plans (in shares)	180
Stock-based compensation expense	$ 0	30,728	0	0	30,728
Balance at Jun. 30, 2024	$ 146	$ 2,303,369	$ (34,838)	$ (2,004,979)	$ 263,698
Balance (in shares) at Jun. 30, 2024	146,025

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Operating activities:
Net loss	$ (66,265)	$ (85,290)	$ (209,068)	$ (209,613)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation			5,013	5,225
Amortization of right-of-use operating lease assets			4,957	4,826
Amortization of other assets			1,260	1,244
Amortization of discount on investments, net			(19,143)	(12,481)
Amortization of debt issuance costs			3,338	2,966
Non-cash royalty revenue related to sale of royalties			(16,236)	(12,562)
Non-cash interest related to sale of future royalties			35,949	32,915
Stock-based compensation expense			62,068	53,510
Loss (gain) on investments			1,201	(301)
Gain on early retirement of debt			0	(11,292)
Non-cash losses related to other assets			389	775
Changes in operating assets and liabilities:
Contracts receivable			70,519	(2,254)
Inventories			(298)	(3,505)
Other current and long-term assets			(9,381)	(19,696)
Income taxes			(1,867)	18,483
Accounts payable			(17,064)	5,517
Accrued compensation			(32,709)	(19,856)
Accrued liabilities and other current liabilities			(39,201)	(37,562)
Deferred contract revenue			(109,545)	(27,695)
Net cash used in operating activities			(269,818)	(231,356)
Investing activities:
Purchases of short-term investments			(803,867)	(932,362)
Proceeds from sale of short-term investments			968,413	701,034
Purchases of property, plant and equipment			(10,727)	(22,483)
Acquisition of licenses and other assets, net			(15,264)	(2,314)
Net cash provided by (used in) investing activities			138,555	(256,125)
Financing activities:
Proceeds from equity, net			26,205	4,950
Proceeds from issuance of 1.75 percent convertible senior notes			0	575,000
1.75 percent convertible senior notes issuance costs			0	(13,658)
Repurchase of $434.1 million principal amount of 0.125 percent convertible senior notes			0	(420,158)
Proceeds from sale of future royalties			0	500,000
Payments of transaction costs related to sale of future royalties			0	(10,434)
Principal payments on mortgage debt			(78)	(75)
Net cash provided by financing activities			26,127	635,625
Effects of exchange rates on cash			(137)	174
Net increase (decrease) in cash and cash equivalents			(105,273)	148,318
Cash and cash equivalents at beginning of period			399,266	276,472	$ 276,472
Cash and cash equivalents at end of period	$ 293,993	$ 424,790	293,993	424,790	$ 399,266
Supplemental disclosures of cash flow information:
Interest paid			5,569	529
Income taxes paid			1,992	510
Supplemental disclosures of non-cash investing and financing activities:
Amounts accrued for capital and patent expenditures			$ 1,453	$ 251

CONDENSED CONSOLIDATED STATEM_5

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) $ in Millions	Jun. 30, 2024 USD ($)
1.75 Percent Convertible Senior Notes [Member]
Financing activities:
Interest rate on convertible senior notes	1.75%
0.125 Percent Convertible Senior Notes [Member]
Financing activities:
Interest rate on convertible senior notes	0.125%
Principal amount repurchased	$ 434.1

Organization and Basis of Prese

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2024
Organization and Basis of Presentation [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Organization and Business Activity We incorporated in California on January 10, 1989. In conjunction with our initial public offering, we reorganized as a Delaware corporation in April 1991. We are a leader in the discovery and development of RNA-targeted therapeutics. Basis of Presentation We prepared the unaudited interim condensed consolidated financial statements for the three and six months ended June 30, 2024 and 2023 on the same basis as the audited financial statements for the year ended December 31, 2023. We included all normal recurring adjustments in the financial statements, which we considered necessary for a fair presentation of our financial position at such dates and our operating results and cash flows for those periods. Our operating results for the interim periods may not be indicative of what our operating results will be for the entire year. For more complete financial information, these financial statements, and notes thereto, should be read in conjunction with the audited financial statements for the year ended December 31, 2023 included in our Annual Report on Form 10-K filed with the Securities and Exchange Commission, or SEC. In our condensed consolidated financial statements, we included the accounts of Ionis Pharmaceuticals, Inc. and the consolidated results of our wholly owned subsidiary, Akcea Therapeutics, Inc. and its wholly owned subsidiaries (“we”, “us” or “our”). We operate as a single single Use of Estimates We prepare our condensed consolidated financial statements in conformity with accounting principles generally accepted in the United States, or

Significant Accounting Policies

Significant Accounting Policies	6 Months Ended
	Jun. 30, 2024
Significant Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies Our significant accounting policies have not changed substantially from those included in our Annual Report on Form 10-K for the year ended December 31, 2023. Recently Issued Accounting Standards We do not expect any recently issued accounting standards to have a material impact to our financial results.

Supplemental Financial Data

Supplemental Financial Data	6 Months Ended
	Jun. 30, 2024
Supplemental Financial Data [Abstract]
Supplemental Financial Data	3. Supplemental Financial Data Inventories Our inventory consisted of the following (in thousands): June 30, 2024 December 31, 2023 Raw materials: Raw materials - clinical $ 22,211 $ 20,985 Raw materials - commercial 2,412 1,809 Total raw materials 24,623 22,794 Work in process 3,614 5,477 Finished goods 486 154 Total inventories $ 28,723 $ 28,425 Accrued Liabilities Our accrued liabilities consisted of the following (in thousands): June 30, 2024 December 31, 2023 Clinical development expenses $ 82,017 $ 105,967 In-licensing expenses 10,603 7,454 Commercial expenses 4,583 4,875 Other miscellaneous expenses 17,127 29,598 Total accrued liabilities $ 114,330 $ 147,894

Revenues

Revenues	6 Months Ended
	Jun. 30, 2024
Revenues [Abstract]
Revenues	4. Revenues During the three and six months ended June 30, 2024 and 2023, our revenues were comprised of the following (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue: Commercial revenue: SPINRAZA royalties $ 56,743 $ 61,012 $ 95,198 $ 111,258 WAINUA royalties 3,781 — 4,907 — Other commercial revenue: TEGSEDI and WAYLIVRA revenue, net 8,192 10,655 16,820 17,133 Licensing and other royalty revenue 3,320 6,230 14,704 17,273 Total other commercial revenue 11,512 16,885 31,524 34,406 Total commercial revenue 72,036 77,897 131,629 145,664 Research and development revenue: Collaborative agreement revenue 141,524 91,013 190,870 129,347 WAINUA joint development revenue 11,690 19,501 22,249 43,924 Total research and development revenue 153,214 110,514 213,119 173,271 Total revenue $ 225,250 $ 188,411 $ 344,748 $ 318,935 Revenue Sources The following are sources of revenue and when we typically recognize revenue. Commercial Revenue: SPINRAZA royalties and WAINUA royalties We earn commercial revenue primarily in the form of royalty payments on net sales of SPINRAZA. In 2024, we began earning royalties from WAINUA sales. Commercial Revenue: TEGSEDI and WAYLIVRA revenue, net We earn commercial revenue from TEGSEDI and WAYLIVRA sales under our distribution agreements with Sobi. In addition, we receive royalties from PTC Therapeutics International Limited, or PTC, for TEGSEDI and WAYLIVRA sales. Commercial Revenue: Licensing and other royalty revenue We also recognize as commercial revenue sales milestone payments and royalties we earn under our partnerships. For example, we earn royalty revenue on net sales of QALSODY, which is included in Licensing and other royalty revenue. Research and development revenue under collaboration agreements We enter into collaboration agreements to license and sell our technology on an exclusive or non-exclusive basis. Our collaboration agreements typically contain multiple elements, or performance obligations, including technology licenses or options to obtain technology licenses, research and development, or R&D, services and manufacturing services. Upfront payments: Milestone payments: We recognize milestone payments that relate to an ongoing performance obligation over our period of performance. For example, when we achieve a milestone payment from a partner for advancing a clinical study under a collaboration agreement, we add the milestone payment to the transaction price if the milestone relates to an ongoing R&D services performance obligation and recognize revenue related to the milestone payment over our estimated period of performance. If we have partially completed our performance obligation, then we record a cumulative-effect adjustment in the period we add the milestone payment to the transaction price. Conversely, we recognize in full those milestone payments that we earn based on our partners’ activities when our partner achieves the milestone event and we do not have a performance obligation. License fees: WAINUA (Eplontersen) Collaboration with AstraZeneca In 2021, we entered into a joint development and commercialization agreement with AstraZeneca to develop and commercialize WAINUA for the treatment of transthyretin amyloidosis, or ATTR. We jointly developed and are commercializing WAINUA for the treatment of adults with polyneuropathy caused by hereditary ATTR, or ATTRv-PN. We evaluated our WAINUA collaboration under ASC 808 and identified four material components: (i) the license we granted to AstraZeneca in 2021, (ii) the co-development activities that we and AstraZeneca are performing, (iii) the co-commercialization activities that we and AstraZeneca are performing and (iv) the co-medical affairs activities that we and AstraZeneca are performing. We determined that we had a vendor-customer relationship within the scope of Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers We also concluded that the co-development activities, the co-commercialization activities and the co-medical affairs activities are within the scope of ASC Topic 808, Collaborative Arrangements

Collaborative Arrangements and

Collaborative Arrangements and Licensing Agreements	6 Months Ended
	Jun. 30, 2024
Collaborative Arrangements and Licensing Agreements [Abstract]
Collaborative Arrangements and Licensing Agreements	5. Collaborative Arrangements and Licensing Agreements Below, we have included our AstraZeneca, Biogen, Otsuka and Roche collaborations, which are the collaborations with substantive changes during 2024 from those included in Part IV, Item 15, Note 4, Collaborative Arrangements and Licensing Agreements , of our audited financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2023. AstraZeneca We have collaborations with AstraZeneca, focused on the joint development and commercialization of WAINUA and focused on the treatment of cardiovascular, renal and metabolic diseases. From inception through , we have received more than $ million from these collaborations. Over the term of our WAINUA collaboration, we are eligible to receive up to $3.6 billion, which is comprised of a $200 million upfront payment, up to $485 million in development and approval milestone payments and up to $2.9 billion in sales milestone payments. The agreement includes territory-specific development, commercial and medical affairs cost-sharing provisions. In addition, we are eligible to receive up to mid-20 percent royalties for sales in the U.S. and tiered royalties up to the high teens for sales outside the U.S. In January 2024, we and AstraZeneca launched WAINUA in the U.S. for the treatment of adults with ATTRv-PN. As a result, we began earning royalties from WAINUA sales, which we recognize as commercial revenue in our condensed consolidated statements of operations. We will achieve the next payment of up to $30 million upon regulatory approval of WAINUA for ATTRv-PN in the European Union, or EU, under this collaboration. During the three and six months ended June 30, 2024 and 2023, we earned the following revenue from our relationship with AstraZeneca (in thousands, except percentage amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue from our relationship with AstraZeneca $ 15,960 $ 59,501 $ 27,645 $ 83,926 Percentage of total revenue 7 % 32 % 8 % 26 % Our condensed consolidated balance sheet at June 30, 2024 included deferred contract revenue of $1.9 million from our relationship with AstraZeneca. We did not have any deferred contract revenue from our relationship with AstraZeneca at December 31, 2023. Biogen We have several strategic collaborations with Biogen focused on using antisense technology to advance the treatment of neurological disorders. We developed and licensed to Biogen SPINRAZA, our approved medicine to treat people with spinal muscular atrophy, or SMA. QALSODY, our medicine to treat patients with superoxide dismutase 1 amyotrophic lateral sclerosis, or SOD1-ALS, received accelerated approval from the U.S. Food and Drug Administration, or FDA, in April 2023 and marketing authorization under exceptional circumstances from the European Medicines Agency, or EMA, in May 2024. In addition, we and Biogen are currently developing numerous other investigational medicines to treat neurodegenerative diseases, including medicines in development to treat people with amyotrophic lateral sclerosis, or ALS, SMA, Alzheimer’s disease, or AD, and Parkinson’s disease, or PD. In addition to these medicines, our collaborations with Biogen include a substantial research pipeline that addresses a broad range of neurological diseases. From inception through June 30, 2024, we have received more than $3.9 billion in payments from our Biogen collaborations, including payments to purchase our stock. Under our 2013 strategic neurology collaboration, we earned a $20 million milestone payment from Biogen when the EMA approved Biogen’s Marketing Authorization Application, or MAA, filing of QALSODY in the second quarter of 2024. We recognized this milestone payment as R&D revenue in full in the second quarter of 2024 because we did not have any remaining performance obligations related to the milestone payment. We will achieve the next milestone payment for QALSODY of $10 million if the Ministry of Health, Labour and Welfare of Japan approves Biogen’s Japanese New Drug Application filing of QALSODY. In the second quarter of 2024, Biogen's option to license ION582, an investigational antisense medicine for the potential treatment of Angelman Syndrome, expired unexercised. As a result, we recognized $30 million of R&D revenue from previously deferred milestone payments related to the ION582 study because we did not have any remaining performance obligations. We will achieve the next milestone payment of $25 million if Biogen advances IONIS-MAPT Rx During the three and six months ended June 30, 2024 and 2023, we earned the following revenue from our relationship with Biogen (in thousands, except percentage amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue from our relationship with Biogen $ 138,159 $ 97,402 $ 197,395 $ 167,903 Percentage of total revenue 61 % 52 % 57 % 53 % Our condensed consolidated balance sheets at June 30, 2024 and December 31, 2023 Otsuka In 2023, we entered into an agreement with Otsuka Pharmaceutical Co., Ltd., or Otsuka, to commercialize donidalorsen in Europe. In the second quarter of 2024, we expanded the agreement to include commercialization rights for donidalorsen in the Asia-Pacific region in addition to Europe. As a result, we received a $ million upfront payment from Otsuka. Under the amended agreement, we are eligible to receive up to $ million, which is comprised of $ million in upfront payments, up to $ million in regulatory milestone payments and up to $ million in sales milestone payments over the term of the collaboration. In addition, we are eligible to receive tiered royalties up to on net sales. We are responsible for completing the ongoing development of donidalorsen. We retained the rights to commercialize donidalorsen in the U.S. and in the rest of the world, assuming regulatory approvals. We identified two performance obligations under our amended agreement for the Asia-Pacific region, comprised of our license of donidalorsen to Otsuka and R&D services for donidalorsen. We allocated the transaction price of $20 million based on the estimated stand-alone selling price of each performance obligation as follows: ● $17.5 million for the license of donidalorsen; and ● $2.5 million for the R&D services for donidalorsen. In the second quarter of 2024, we recognized $17.5 million as revenue in full because Otsuka had full use of the license without any continuing involvement from us. We are recognizing revenue for our R&D services performance obligation as we perform services based on our effort to satisfy our performance obligation relative to our total effort expected to satisfy our performance obligation. We currently estimate we will satisfy our R&D services performance obligation in March 2026. We will achieve the next payment of $15 million if the EMA accepts a MAA filing for donidalorsen in the EU under this collaboration. During the three and six months ended June 30, 2024 and 2023, we earned the following revenue from our relationship with Otsuka (in thousands, except percentage amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue from our relationship with Otsuka $ 18,905 $ — $ 19,691 $ — Percentage of total revenue 8 % 0 % 6 % 0 % Our condensed consolidated balance sheets at June 30, 2024 and December 31, 2023 Roche We have three collaborations with Hoffmann-La Roche Inc. and F. Hoffmann-La Roche Ltd, collectively Roche: one to develop IONIS-FB-L Rx In July 2024, Roche discontinued development Rx Over the term of the IONIS-FB-L Rx Rx During the three and six months ended June 30, 2024 and 2023, we earned the following revenue from our relationship with Roche (in thousands, except percentage amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue from our relationship with Roche $ 11,089 $ 5,754 $ 22,595 $ 8,121 Percentage of total revenue 5 % 3 % 7 % 3 % Our condensed consolidated balance sheets at June 30, 2024 and December 31, 2023 included deferred contract revenue of $15.0 million and $36.7 million, respectively, from our relationship with Roche.

Basic and Diluted Net Loss Per

Basic and Diluted Net Loss Per Share	6 Months Ended
	Jun. 30, 2024
Basic and Diluted Net Loss Per Share [Abstract]
Basic and Diluted Net Loss Per Share	6. Basic and Diluted Net Loss Per Share Basic net loss per share We calculated our basic net loss per share for the three and six months ended June 30, 2024 and 2023 by dividing our net loss by our weighted-average number of common shares outstanding during the period. Diluted net loss per share For the three and six months ended June 30, 2024 and 2023, we incurred a net loss; therefore, we did not include dilutive common equivalent shares in the computation of diluted net loss per share because the effect would have been anti-dilutive. Common stock from the following would have had an anti-dilutive effect on net loss per share: ● 1.75 percent convertible senior notes, or 1.75% Notes; ● 0 percent convertible senior notes, or 0% Notes; ● Note hedges related to the 0% Notes; ● 0.125 percent convertible senior notes, or 0.125% Notes; ● Note hedges related to the 0.125% Notes; ● Dilutive stock options; ● Unvested restricted stock units, or RSUs; ● Unvested performance restricted stock units, or PRSUs; and ● Employee Stock Purchase Plan, or ESPP. Additionally, as of June 30, 2024 and 2023, we had warrants related to our 0% and 0.125% Notes outstanding. We will include the shares issuable under these warrants in our calculation of diluted earnings per share when the average market price per share of our common stock for the reporting period exceeds the strike price of the warrants.

Investments

Investments	6 Months Ended
	Jun. 30, 2024
Investments [Abstract]
Investments	7. Investments The following table summarizes the contract maturity of the available-for-sale securities we held as of June 30, 2024: One year 75 % After one year two years 21 % After two years three and a half years 4 % Total 100 % As illustrated above, at June 30, 2024, 96 percent of our available-for-sale securities had a maturity of less than two years. All of our available-for-sale debt securities are available to us for use in our current operations. As a result, we categorize all of these securities as current assets even though the stated maturity of some individual securities may be one year or more beyond the balance sheet date. We invest in debt securities At June 30, 2024, we had an equity ownership interest of less than 20 percent in seven private companies and three public companies with which we conduct business. The following is a summary of our investments (in thousands): Amortized Gross Unrealized Estimated June 30, 2024 Cost Gains Losses Fair Value Available-for-sale debt securities: Corporate debt securities (1) $ 552,837 $ 36 $ (1,569 ) $ 551,304 Debt securities issued by U.S. government agencies 121,781 5 (310 ) 121,476 Debt securities issued by the U.S. Treasury (1) 650,997 12 (1,105 ) 649,904 Debt securities issued by states of the U.S. and political subdivisions of the states 18,083 14 (42 ) 18,055 Total debt securities with a maturity of one year or less 1,343,698 67 (3,026 ) 1,340,739 Corporate debt securities 218,639 191 (874 ) 217,956 Debt securities issued by U.S. government agencies 115,349 72 (317 ) 115,104 Debt securities issued by the U.S. Treasury 127,240 12 (1,135 ) 126,117 Debt securities issued by states of the U.S. and political subdivisions of the states 1,668 — (8 ) 1,660 Total debt securities with a maturity of more than one year 462,896 275 (2,334 ) 460,837 Total available-for-sale debt securities $ 1,806,594 $ 342 $ (5,360 ) $ 1,801,576 Equity securities: Publicly traded equity securities included in other current assets (2) $ 11,897 $ 334 $ (5,377 ) $ 6,854 Privately held equity securities included in deposits and other assets (3) 23,115 25,001 (7,093 ) 41,023 Total equity securities 35,012 25,335 (12,470 ) 47,877 Total available-for-sale debt and equity securities $ 1,841,606 $ 25,677 $ (17,830 ) $ 1,849,453 Amortized Gross Unrealized Estimated December 31, 2023 Cost Gains Losses Fair Value Available-for-sale debt securities: Corporate debt securities (1) $ 559,967 $ 157 $ (2,625 ) $ 557,499 Debt securities issued by U.S. government agencies 224,711 64 (611 ) 224,164 Debt securities issued by the U.S. Treasury (1) 513,784 152 (1,889 ) 512,047 Debt securities issued by states of the U.S. and political subdivisions of the states 17,757 42 (113 ) 17,686 Total debt securities with a maturity of one year or less 1,316,219 415 (5,238 ) 1,311,396 Corporate debt securities 243,151 1,270 (692 ) 243,729 Debt securities issued by U.S. government agencies 110,138 547 (21 ) 110,664 Debt securities issued by the U.S. Treasury 294,873 1,239 (480 ) 295,632 Debt securities issued by states of the U.S. and political subdivisions of the states 3,466 7 (4 ) 3,469 Total debt securities with a maturity of more than one year 651,628 3,063 (1,197 ) 653,494 Total available-for-sale debt securities $ 1,967,847 $ 3,478 $ (6,435 ) $ 1,964,890 Equity securities: Publicly traded equity securities included in other current assets (2) $ 11,897 $ 236 $ (5,832 ) $ 6,301 Privately held equity securities included in deposits and other assets (3) 23,115 25,001 (5,125 ) 42,991 Total equity securities 35,012 25,237 (10,957 ) 49,292 Total available-for-sale debt and equity securities $ 2,002,859 $ 28,715 $ (17,392 ) $ 2,014,182 (1) Includes investments classified as cash equivalents in our condensed consolidated balance sheets. (2) Our publicly traded equity securities are included in other current assets. We recognize publicly traded equity securities at fair value. In the six months ended June 30, 2024, we recorded a $0.6 million net unrealized gain in our condensed consolidated statements of operations related to changes in the fair value of our investments in publicly traded companies. (3) Our privately held equity securities are included in deposits and other assets. We recognize our privately held equity securities at . In the , we recorded a loss of $ million in our condensed consolidated statements of operations related to changes in the fair value of our investments in privately held companies. The following is a summary of our investments we consider to be temporarily impaired at June 30, 2024 (in thousands, except for number of investments): Less than 12 Months of Temporary Impairment More than 12 Months of Temporary Impairment Total Temporary Impairment Number of Investments Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Corporate debt securities 440 $ 517,394 $ (1,155 ) $ 142,390 $ (1,288 ) $ 659,784 $ (2,443 ) Debt securities issued by U.S. government agencies 108 173,618 (482 ) 25,892 (145 ) 199,510 (627 ) Debt securities issued by the U.S. Treasury 71 561,363 (862 ) 154,006 (1,378 ) 715,369 (2,240 ) Debt securities issued by states of the U.S. and political subdivisions of the states 45 8,449 (23 ) 9,319 (27 ) 17,768 (50 ) Total temporarily impaired securities 664 $ 1,260,824 $ (2,522 ) $ 331,607 $ (2,838 ) $ 1,592,431 $ (5,360 ) We believe that the decline in value of these securities is temporary and is primarily related to the change in market interest rates since purchase rather than underlying credit deterioration for any of the issuers. We believe it is more likely than not that we will be able to hold our debt securities with declines in value to maturity. Therefore, we intend to hold these securities to maturity and anticipate full recovery of our debt securities’ amortized cost basis at maturity.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2024
Fair Value Measurements [Abstract]
Fair Value Measurements	8. Fair Value Measurements The following tables present the major security types we held at June 30, 2024 and December 31, 2023 that we regularly measure and carry at fair value. The following tables segregate each security type by the level within the fair value hierarchy of the valuation techniques we utilized to determine the respective security’s fair value (in thousands): At June 30, 2024 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Cash equivalents (1) $ 212,489 $ 212,489 $ — Corporate debt securities (2) 769,260 — 769,260 Debt securities issued by U.S. government agencies (3) 236,580 — 236,580 Debt securities issued by the U.S. Treasury (3) 776,021 776,021 — Debt securities issued by states of the U.S. and political subdivisions of the states (3) 19,715 — 19,715 Publicly traded equity securities included in other current assets (4) 6,854 6,854 — Total $ 2,020,919 $ 995,364 $ 1,025,555 At December 31, 2023 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Cash equivalents (1) $ 185,424 $ 185,424 $ — Corporate debt securities (5) 801,228 — 801,228 Debt securities issued by U.S. government agencies (3) 334,828 — 334,828 Debt securities issued by the U.S. Treasury (3) 807,679 807,679 — Debt securities issued by states of the U.S. and political subdivisions of the states (3) 21,155 — 21,155 Publicly traded equity securities included in other current assets (4) 6,301 6,301 — Total $ 2,156,615 $ 999,404 $ 1,157,211 The following footnotes reference lines in our condensed consolidated balance sheets: (1) Included in cash and cash equivalents. (2) $16.9 million was included in cash and cash equivalents, with the difference included in short-term investments. (3) Included in short-term investments. (4) Included in other current assets. (5) $33.0 million was included in cash and cash equivalents, with the difference included in short-term investments. Convertible Notes Our 1.75% Notes, 0% Notes and 0.125% Notes had a fair value of $634.4 million, $649.6 million and $43.4 million at June 30, 2024, respectively. Our 1.75% Notes, 0% Notes and 0.125% Notes had a fair value of $661.1 million, $667.8 million and $42.4 million at December 31, 2023, respectively. We determine the fair value of our notes based on quoted market prices for these notes, which are Level 2 measurements because the notes do not trade regularly.

Stock-based Compensation Expens

Stock-based Compensation Expense	6 Months Ended
	Jun. 30, 2024
Stock-based Compensation Expense [Abstract]
Stock-based Compensation Expense	9. Stock-based Compensation Expense The following table summarizes stock-based compensation expense for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Cost of sales $ 246 $ 118 $ 450 $ 237 Research, development and patent expense 22,766 19,249 44,991 38,816 Selling, general and administrative expense 7,716 7,194 16,627 14,457 Total stock-based compensation expense $ 30,728 $ 26,561 $ 62,068 $ 53,510 As of June 30, 2024, total unrecognized estimated stock-based compensation expense related to non-vested stock options, RSUs and PRSUs was $61.6 million, $96.7 million and $13.8 million, respectively. Our actual expenses may differ from these estimates because we will adjust our unrecognized stock-based compensation expense for future forfeitures, including any PRSUs that do not vest. We expect to recognize the cost of stock-based compensation expense related to our non-vested stock options, RSUs and PRSUs over a weighted average amortization period of 1.3 years, 1.6 years and 1.9 years, respectively. Refer to Part IV, Item 15, Note 1, Organization and Significant Accounting Policies For the six months ended June 30, 2024 and 2023, we used the following weighted-average assumptions in our Black-Scholes calculations: Employee Stock Options: Six Months Ended June 30, 2024 2023 Risk-free interest rate 4.1 % 3.6 % Dividend yield 0.0 % 0.0 % Volatility 43.9 % 47.3 % Expected life 6.3 years 6.3 years ESPP: Six Months Ended June 30, 2024 2023 Risk-free interest rate 5.3 % 5.2 % Dividend yield 0.0 % 0.0 % Volatility 38.4 % 36.7 % Expected life 6 months 6 months RSUs: The weighted-average grant date fair value of RSUs granted to employees for the six months ended June 30, 2024 and 2023 was $52.60 and $39.50 per share, respectively. PRSUs: Under the terms of the PRSUs we granted in 2024 and 2023, 100 percent of the PRSUs may vest at the end of the three-year performance period based on our relative TSR as compared to a peer group of companies and as measured at the end of the performance period. Under the terms of the grants, no number of PRSUs is guaranteed to vest and the actual number of PRSUs that will vest at the end of each performance period may be anywhere from zero to 200 percent of the target number depending on our relative TSR. The weighted-average grant date fair value of PRSUs we granted to our executive officers for the six months ended June 30, 2024 and 2023 was $78.41 and $58.99 per share, respectively.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2024
Income Taxes [Abstract]
Income Taxes	10. Income Taxes We recorded income tax expense of $0.1 million and $0.1 million for the three and six months ended June 30, 2024, respectively, compared to $7.8 million and $19.2 million for the same periods in 2023, respectively. The decrease in income tax expense relates primarily to the impact of the royalty purchase agreement with Royalty Pharma on income tax expense for the three and six months ended June 30, 2023. We reflected the Royalty Pharma transaction as a taxable sale, which required us to include the proceeds from the sale, net of currently deductible issuance costs, as taxable income in 2023. We continue to maintain a full valuation allowance on all our net deferred tax assets.

Liability Related to Sale of Fu

Liability Related to Sale of Future Royalties	6 Months Ended
	Jun. 30, 2024
Liability Related to Sale of Future Royalties [Abstract]
Liability Related to Sale of Future Royalties	11. Liability Related to Sale of Future Royalties In January 2023, we entered into a royalty purchase agreement with Royalty Pharma to monetize a portion of our future SPINRAZA and pelacarsen royalties we are entitled to under our arrangements with Biogen and Novartis, respectively. As a result, we received an upfront payment of $500 million and we are eligible to receive up to $625 million in additional milestone payments. Under the terms of the agreement, Royalty Pharma will receive 25 percent of our SPINRAZA royalty payments from 2023 through 2027, increasing to 45 percent of royalty payments in 2028, on up to $1.5 billion in annual sales. In addition, Royalty Pharma will receive 25 percent of any future royalty payments on pelacarsen, our medicine in development to treat patients with elevated lipoprotein(a)-driven cardiovascular disease. Royalty Pharma’s royalty interest in SPINRAZA will revert to us after total SPINRAZA royalty payments to Royalty Pharma reach either $475 million or $550 million, depending on the timing and occurrence of FDA approval of pelacarsen. We recorded the upfront payment of $500 million as a liability related to the sale of future royalties, net of transaction costs of $10.4 million, which we are amortizing over the estimated life of the arrangement using the effective interest rate method. We recognize royalty revenue in the period in which the counterparty sells the related product and recognizes the related revenue. We record royalty payments made to Royalty Pharma as a reduction of the liability. We determine the effective interest rate used to record interest expense under this agreement based on an estimate of future royalty payments to Royalty Pharma. As of June 30, 2024, the estimated effective interest rate under the agreement was 13.5 percent. The following table sets forth information on our liability related to sale of future royalties (in thousands): Proceeds from sale of future royalties in January 2023 $ 500,000 Issuance costs related to sale of future royalties (10,434 ) Royalty payments to Royalty Pharma (44,628 ) Interest expense related to sale of future royalties 68,238 Amortization of issuance costs related to sale of future royalties 560 Net liability related to sale of future royalties as of December 31, 2023 513,736 Royalty payments to Royalty Pharma (16,236 ) Interest expense related to sale of future royalties 35,949 Amortization of issuance costs related to sale of future royalties 305 Net liability related to sale of future royalties as of June 30, 2024 $ 533,754 There are numerous factors, most of which are not within our control, that could materially impact the amount and timing of royalty payments from Biogen and Novartis, and result in changes to our estimate of future royalty payments to Royalty Pharma. Such factors include, but are not limited to, the commercial sales of SPINRAZA, the regulatory approval and commercial sales of pelacarsen, competing products or other significant events.

Convertible Debt

Convertible Debt	6 Months Ended
	Jun. 30, 2024
Convertible Debt [Abstract]
Convertible Debt	12. Convertible Debt 1.75 Percent Convertible Senior Notes In 2023, we completed a $575.0 million offering of convertible senior notes and used $488.2 million of the net proceeds from the issuance of the 1.75% Notes to repurchase $504.4 million in principal of our 0.125% Notes. We expect to use the remaining net proceeds to settle the 0.125% Notes that remain outstanding and for general corporate and working capital purposes. At June 30, 2024, we had the following 1.75% Notes outstanding (in millions except interest rate and price per share data): 1.75% Notes Outstanding principal balance $ 575.0 Unamortized debt issuance costs $ 11.4 Maturity date June 2028 Interest rate 1.75 % Effective interest rate 2.3 % Conversion price per share $ 53.73 Total shares of common stock subject to conversion 10.7 0 Percent Convertible Senior Notes and Call Spread At June 30, 2024, we had the following 0% 0% Notes Outstanding principal balance $ 632.5 Unamortized debt issuance costs $ 5.5 Maturity date April 2026 Interest rate 0 % Effective interest rate 0.5 % Conversion price per share $ 57.84 Effective conversion price per share with call spread $ 76.39 Total shares of common stock subject to conversion 10.9 In conjunction with the 2021 offering, we entered into a call spread transaction, which was comprised of purchasing note hedges and selling warrants, to minimize the impact of potential economic dilution upon conversion of our 0% 0% 0% 0% 0% 0% 0% 0% We recorded the amount we paid for the note hedges and the amount we received for the warrants in additional paid-in capital in our condensed consolidated balance sheets. Refer to Part IV, Item 15, Note 1, Organization and Significant Accounting Policies 0.125 Percent Convertible Senior Notes and Call Spread As discussed above, in 2023, we repurchased $504.4 million of our 0.125% Notes. At June 30, 2024, we had the following 0.125% Notes outstanding with interest payable semi-annually (in millions except interest rate and price per share data): 0.125% Notes Outstanding principal balance $ 44.5 Unamortized debt issuance costs $ 0.1 Maturity date December 2024 Interest rate 0.125 % Effective interest rate 0.5 % Conversion price per share $ 83.28 Effective conversion price per share with call spread $ 123.38 Total shares of common stock subject to conversion, excluding shares related to 0.125 0.5 In conjunction with the issuance of our Notes in 2019, we entered into a call spread transaction, which was comprised of purchasing note hedges and selling warrants, to minimize the impact of potential economic dilution upon conversion of our . We increased our effective conversion price to $ with the same number of underlying shares as our Notes. The call spread cost us $ million, of which $ million was for the note hedge purchase, offset by $ million we received for selling the warrants. Similar to our , our note hedges are subject to adjustment. Additionally, our note hedges are exercisable upon conversion of the . The note hedges will expire upon maturity of the , or December 2024. The note hedges and warrants are separate transactions and are not part of the terms of our . The holders of the do not have any rights with respect to the note hedges and warrants. As of , the note hedges and warrants remain outstanding. We recorded the amount we paid for the note hedges and the amount we received for the warrants in additional paid-in capital in our condensed consolidated balance sheets. We reassess our ability to continue to classify the note hedges and warrants in shareholders’ equity at each reporting period. Other Terms of Convertible Senior Notes The , 0% and Notes are convertible under certain conditions, at the option of the note holders. We can settle conversions of the notes, at our election, in cash, shares of our common stock or a combination of both. We may not redeem the notes prior to maturity, and we do not have to provide a sinking fund for them. Holders of the notes may require us to purchase some or all of their notes upon the occurrence of certain fundamental changes, as set forth in the indentures governing the notes, at a purchase price equal to of the principal amount of the notes to be purchased, plus any accrued and unpaid interest.

Legal Proceedings

Legal Proceedings	6 Months Ended
	Jun. 30, 2024
Legal Proceedings [Abstract]
Legal Proceedings	13. Legal Proceedings From time to time, we are involved in legal proceedings arising in the ordinary course of our business. Periodically, we evaluate the status of each legal matter and assess our potential financial exposure. If we consider the potential loss from any legal proceeding to be probable and we can reasonably estimate the amount, we accrue a liability for the estimated loss. The outcome of any proceeding is not determinable in advance. Therefore, we are required to use significant judgment to determine the probability of a loss and whether the amount of the loss is reasonably estimable. Our assessment of a potential liability and the amount of accruals we recorded are based only on the information available to us at the time. As additional information becomes available, we reassess the potential liability related to the legal proceeding and may revise our estimates. There are no pending material legal proceedings to which we are a party or of which our property is the subject.

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Jun. 30, 2024 shares
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	During the quarter ended June 30, 2024, our Section 16 officers and directors adopted or terminated contracts, instructions or written plans for the purchase or sale of our securities as noted in the table below. * Contract, instruction or written plan intended to satisfy the affirmative defense conditions of Rule 10b5-1(c) under the Exchange Act. ** “Non-Rule 10b5-1 trading arrangement” as defined in item 408(c) of Regulation S-K under the Exchange Act. Action Date Trading Arrangement Total Shares to Be Sold Expiration Date Rule 10b5-1* Non-Rule 10b5-1** Brett P. Monia Chief Executive Officer Termination June 26, 2024 X 54,442 Upon the execution of all instructions provided in the plan Richard S. Geary EVP, Chief Development Officer Adoption April 8, 2024 X 241,732 The earlier to occur of (i) July 7, 2025
Brett Monia [Member]
Trading Arrangements, by Individual
Name	Brett P. Monia
Title	Chief Executive Officer
Rule 10b5-1 Arrangement Terminated	true
Non-Rule 10b5-1 Arrangement Terminated	false
Termination Date	June 26, 2024
Arrangement Duration
Aggregate Available	54,442
Richard S. Geary [Member]
Trading Arrangements, by Individual
Name	Richard S. Geary
Title	EVP, Chief Development Officer
Rule 10b5-1 Arrangement Adopted	true
Non-Rule 10b5-1 Arrangement Adopted	false
Adoption Date	April 8, 2024
Arrangement Duration	456 days
Aggregate Available	241,732

Organization and Basis of Pre_2

Organization and Basis of Presentation (Policies)	6 Months Ended
	Jun. 30, 2024
Organization and Basis of Presentation [Abstract]
Basis of Presentation	We prepared the unaudited interim condensed consolidated financial statements for the three and six months ended June 30, 2024 and 2023 on the same basis as the audited financial statements for the year ended December 31, 2023. We included all normal recurring adjustments in the financial statements, which we considered necessary for a fair presentation of our financial position at such dates and our operating results and cash flows for those periods. Our operating results for the interim periods may not be indicative of what our operating results will be for the entire year. For more complete financial information, these financial statements, and notes thereto, should be read in conjunction with the audited financial statements for the year ended December 31, 2023 included in our Annual Report on Form 10-K filed with the Securities and Exchange Commission, or SEC.
Consolidation	In our condensed consolidated financial statements, we included the accounts of Ionis Pharmaceuticals, Inc. and the consolidated results of our wholly owned subsidiary, Akcea Therapeutics, Inc. and its wholly owned subsidiaries (“we”, “us” or “our”).
Segment Information	We operate as a single single
Use of Estimates	Use of Estimates We prepare our condensed consolidated financial statements in conformity with accounting principles generally accepted in the United States, or

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2024
Significant Accounting Policies [Abstract]
Recently Issued Accounting Standards	Recently Issued Accounting Standards We do not expect any recently issued accounting standards to have a material impact to our financial results.

Basic and Diluted Net Loss Pe_2

Basic and Diluted Net Loss Per Share (Policies)	6 Months Ended
	Jun. 30, 2024
Basic and Diluted Net Loss Per Share [Abstract]
Basic and Diluted Net Loss Per Share	Basic net loss per share We calculated our basic net loss per share for the three and six months ended June 30, 2024 and 2023 by dividing our net loss by our weighted-average number of common shares outstanding during the period. Diluted net loss per share For the three and six months ended June 30, 2024 and 2023, we incurred a net loss; therefore, we did not include dilutive common equivalent shares in the computation of diluted net loss per share because the effect would have been anti-dilutive. Common stock from the following would have had an anti-dilutive effect on net loss per share: ● 1.75 percent convertible senior notes, or 1.75% Notes; ● 0 percent convertible senior notes, or 0% Notes; ● Note hedges related to the 0% Notes; ● 0.125 percent convertible senior notes, or 0.125% Notes; ● Note hedges related to the 0.125% Notes; ● Dilutive stock options; ● Unvested restricted stock units, or RSUs; ● Unvested performance restricted stock units, or PRSUs; and ● Employee Stock Purchase Plan, or ESPP. Additionally, as of June 30, 2024 and 2023, we had warrants related to our 0% and 0.125% Notes outstanding. We will include the shares issuable under these warrants in our calculation of diluted earnings per share when the average market price per share of our common stock for the reporting period exceeds the strike price of the warrants.

Supplemental Financial Data (Ta

Supplemental Financial Data (Tables)	6 Months Ended
	Jun. 30, 2024
Supplemental Financial Data [Abstract]
Inventories	Inventories Our inventory consisted of the following (in thousands): June 30, 2024 December 31, 2023 Raw materials: Raw materials - clinical $ 22,211 $ 20,985 Raw materials - commercial 2,412 1,809 Total raw materials 24,623 22,794 Work in process 3,614 5,477 Finished goods 486 154 Total inventories $ 28,723 $ 28,425
Accrued Liabilities	Accrued Liabilities Our accrued liabilities consisted of the following (in thousands): June 30, 2024 December 31, 2023 Clinical development expenses $ 82,017 $ 105,967 In-licensing expenses 10,603 7,454 Commercial expenses 4,583 4,875 Other miscellaneous expenses 17,127 29,598 Total accrued liabilities $ 114,330 $ 147,894

Revenues (Tables)

Revenues (Tables)	6 Months Ended
	Jun. 30, 2024
Revenues [Abstract]
Revenues	During the three and six months ended June 30, 2024 and 2023, our revenues were comprised of the following (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue: Commercial revenue: SPINRAZA royalties $ 56,743 $ 61,012 $ 95,198 $ 111,258 WAINUA royalties 3,781 — 4,907 — Other commercial revenue: TEGSEDI and WAYLIVRA revenue, net 8,192 10,655 16,820 17,133 Licensing and other royalty revenue 3,320 6,230 14,704 17,273 Total other commercial revenue 11,512 16,885 31,524 34,406 Total commercial revenue 72,036 77,897 131,629 145,664 Research and development revenue: Collaborative agreement revenue 141,524 91,013 190,870 129,347 WAINUA joint development revenue 11,690 19,501 22,249 43,924 Total research and development revenue 153,214 110,514 213,119 173,271 Total revenue $ 225,250 $ 188,411 $ 344,748 $ 318,935

Collaborative Arrangements an_2

Collaborative Arrangements and Licensing Agreements (Tables)	6 Months Ended
	Jun. 30, 2024
AstraZeneca [Member]
Collaborative Arrangements and Licensing Agreements [Abstract]
Revenue from Collaborative Relationship	During the three and six months ended June 30, 2024 and 2023, we earned the following revenue from our relationship with AstraZeneca (in thousands, except percentage amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue from our relationship with AstraZeneca $ 15,960 $ 59,501 $ 27,645 $ 83,926 Percentage of total revenue 7 % 32 % 8 % 26 %
Biogen [Member]
Collaborative Arrangements and Licensing Agreements [Abstract]
Revenue from Collaborative Relationship	During the three and six months ended June 30, 2024 and 2023, we earned the following revenue from our relationship with Biogen (in thousands, except percentage amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue from our relationship with Biogen $ 138,159 $ 97,402 $ 197,395 $ 167,903 Percentage of total revenue 61 % 52 % 57 % 53 %
Otsuka [Member]
Collaborative Arrangements and Licensing Agreements [Abstract]
Revenue from Collaborative Relationship	During the three and six months ended June 30, 2024 and 2023, we earned the following revenue from our relationship with Otsuka (in thousands, except percentage amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue from our relationship with Otsuka $ 18,905 $ — $ 19,691 $ — Percentage of total revenue 8 % 0 % 6 % 0 %
Roche [Member]
Collaborative Arrangements and Licensing Agreements [Abstract]
Revenue from Collaborative Relationship	During the three and six months ended June 30, 2024 and 2023, we earned the following revenue from our relationship with Roche (in thousands, except percentage amounts): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Revenue from our relationship with Roche $ 11,089 $ 5,754 $ 22,595 $ 8,121 Percentage of total revenue 5 % 3 % 7 % 3 %

Investments (Tables)

Investments (Tables)	6 Months Ended
	Jun. 30, 2024
Investments [Abstract]
Contract Maturity of Available-for-Sale Securities	The following table summarizes the contract maturity of the available-for-sale securities we held as of June 30, 2024: One year 75 % After one year two years 21 % After two years three and a half years 4 % Total 100 %
Summary of Investments	The following is a summary of our investments (in thousands): Amortized Gross Unrealized Estimated June 30, 2024 Cost Gains Losses Fair Value Available-for-sale debt securities: Corporate debt securities (1) $ 552,837 $ 36 $ (1,569 ) $ 551,304 Debt securities issued by U.S. government agencies 121,781 5 (310 ) 121,476 Debt securities issued by the U.S. Treasury (1) 650,997 12 (1,105 ) 649,904 Debt securities issued by states of the U.S. and political subdivisions of the states 18,083 14 (42 ) 18,055 Total debt securities with a maturity of one year or less 1,343,698 67 (3,026 ) 1,340,739 Corporate debt securities 218,639 191 (874 ) 217,956 Debt securities issued by U.S. government agencies 115,349 72 (317 ) 115,104 Debt securities issued by the U.S. Treasury 127,240 12 (1,135 ) 126,117 Debt securities issued by states of the U.S. and political subdivisions of the states 1,668 — (8 ) 1,660 Total debt securities with a maturity of more than one year 462,896 275 (2,334 ) 460,837 Total available-for-sale debt securities $ 1,806,594 $ 342 $ (5,360 ) $ 1,801,576 Equity securities: Publicly traded equity securities included in other current assets (2) $ 11,897 $ 334 $ (5,377 ) $ 6,854 Privately held equity securities included in deposits and other assets (3) 23,115 25,001 (7,093 ) 41,023 Total equity securities 35,012 25,335 (12,470 ) 47,877 Total available-for-sale debt and equity securities $ 1,841,606 $ 25,677 $ (17,830 ) $ 1,849,453 Amortized Gross Unrealized Estimated December 31, 2023 Cost Gains Losses Fair Value Available-for-sale debt securities: Corporate debt securities (1) $ 559,967 $ 157 $ (2,625 ) $ 557,499 Debt securities issued by U.S. government agencies 224,711 64 (611 ) 224,164 Debt securities issued by the U.S. Treasury (1) 513,784 152 (1,889 ) 512,047 Debt securities issued by states of the U.S. and political subdivisions of the states 17,757 42 (113 ) 17,686 Total debt securities with a maturity of one year or less 1,316,219 415 (5,238 ) 1,311,396 Corporate debt securities 243,151 1,270 (692 ) 243,729 Debt securities issued by U.S. government agencies 110,138 547 (21 ) 110,664 Debt securities issued by the U.S. Treasury 294,873 1,239 (480 ) 295,632 Debt securities issued by states of the U.S. and political subdivisions of the states 3,466 7 (4 ) 3,469 Total debt securities with a maturity of more than one year 651,628 3,063 (1,197 ) 653,494 Total available-for-sale debt securities $ 1,967,847 $ 3,478 $ (6,435 ) $ 1,964,890 Equity securities: Publicly traded equity securities included in other current assets (2) $ 11,897 $ 236 $ (5,832 ) $ 6,301 Privately held equity securities included in deposits and other assets (3) 23,115 25,001 (5,125 ) 42,991 Total equity securities 35,012 25,237 (10,957 ) 49,292 Total available-for-sale debt and equity securities $ 2,002,859 $ 28,715 $ (17,392 ) $ 2,014,182 (1) Includes investments classified as cash equivalents in our condensed consolidated balance sheets. (2) Our publicly traded equity securities are included in other current assets. We recognize publicly traded equity securities at fair value. In the six months ended June 30, 2024, we recorded a $0.6 million net unrealized gain in our condensed consolidated statements of operations related to changes in the fair value of our investments in publicly traded companies. (3) Our privately held equity securities are included in deposits and other assets. We recognize our privately held equity securities at . In the , we recorded a loss of $ million in our condensed consolidated statements of operations related to changes in the fair value of our investments in privately held companies.
Temporarily Impaired Investments	The following is a summary of our investments we consider to be temporarily impaired at June 30, 2024 (in thousands, except for number of investments): Less than 12 Months of Temporary Impairment More than 12 Months of Temporary Impairment Total Temporary Impairment Number of Investments Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Estimated Fair Value Unrealized Losses Corporate debt securities 440 $ 517,394 $ (1,155 ) $ 142,390 $ (1,288 ) $ 659,784 $ (2,443 ) Debt securities issued by U.S. government agencies 108 173,618 (482 ) 25,892 (145 ) 199,510 (627 ) Debt securities issued by the U.S. Treasury 71 561,363 (862 ) 154,006 (1,378 ) 715,369 (2,240 ) Debt securities issued by states of the U.S. and political subdivisions of the states 45 8,449 (23 ) 9,319 (27 ) 17,768 (50 ) Total temporarily impaired securities 664 $ 1,260,824 $ (2,522 ) $ 331,607 $ (2,838 ) $ 1,592,431 $ (5,360 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2024
Fair Value Measurements [Abstract]
Assets Measured at Fair Value on a Recurring Basis	The following tables present the major security types we held at June 30, 2024 and December 31, 2023 that we regularly measure and carry at fair value. The following tables segregate each security type by the level within the fair value hierarchy of the valuation techniques we utilized to determine the respective security’s fair value (in thousands): At June 30, 2024 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Cash equivalents (1) $ 212,489 $ 212,489 $ — Corporate debt securities (2) 769,260 — 769,260 Debt securities issued by U.S. government agencies (3) 236,580 — 236,580 Debt securities issued by the U.S. Treasury (3) 776,021 776,021 — Debt securities issued by states of the U.S. and political subdivisions of the states (3) 19,715 — 19,715 Publicly traded equity securities included in other current assets (4) 6,854 6,854 — Total $ 2,020,919 $ 995,364 $ 1,025,555 At December 31, 2023 Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Cash equivalents (1) $ 185,424 $ 185,424 $ — Corporate debt securities (5) 801,228 — 801,228 Debt securities issued by U.S. government agencies (3) 334,828 — 334,828 Debt securities issued by the U.S. Treasury (3) 807,679 807,679 — Debt securities issued by states of the U.S. and political subdivisions of the states (3) 21,155 — 21,155 Publicly traded equity securities included in other current assets (4) 6,301 6,301 — Total $ 2,156,615 $ 999,404 $ 1,157,211 The following footnotes reference lines in our condensed consolidated balance sheets: (1) Included in cash and cash equivalents. (2) $16.9 million was included in cash and cash equivalents, with the difference included in short-term investments. (3) Included in short-term investments. (4) Included in other current assets. (5) $33.0 million was included in cash and cash equivalents, with the difference included in short-term investments.

Stock-based Compensation Expe_2

Stock-based Compensation Expense (Tables)	6 Months Ended
	Jun. 30, 2024
Stock-based Compensation Expense [Abstract]
Stock-Based Compensation Expense	The following table summarizes stock-based compensation expense for the three and six months ended June 30, 2024 and 2023 (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2024 2023 2024 2023 Cost of sales $ 246 $ 118 $ 450 $ 237 Research, development and patent expense 22,766 19,249 44,991 38,816 Selling, general and administrative expense 7,716 7,194 16,627 14,457 Total stock-based compensation expense $ 30,728 $ 26,561 $ 62,068 $ 53,510
Weighted-Average Assumptions for Stock Options	Employee Stock Options: Six Months Ended June 30, 2024 2023 Risk-free interest rate 4.1 % 3.6 % Dividend yield 0.0 % 0.0 % Volatility 43.9 % 47.3 % Expected life 6.3 years 6.3 years
Weighted-Average Assumptions for ESPP	ESPP: Six Months Ended June 30, 2024 2023 Risk-free interest rate 5.3 % 5.2 % Dividend yield 0.0 % 0.0 % Volatility 38.4 % 36.7 % Expected life 6 months 6 months

Liability Related to Sale of _2

Liability Related to Sale of Future Royalties (Tables)	6 Months Ended
	Jun. 30, 2024
Liability Related to Sale of Future Royalties [Abstract]
Liability Related to Sale of Future Royalties	The following table sets forth information on our liability related to sale of future royalties (in thousands): Proceeds from sale of future royalties in January 2023 $ 500,000 Issuance costs related to sale of future royalties (10,434 ) Royalty payments to Royalty Pharma (44,628 ) Interest expense related to sale of future royalties 68,238 Amortization of issuance costs related to sale of future royalties 560 Net liability related to sale of future royalties as of December 31, 2023 513,736 Royalty payments to Royalty Pharma (16,236 ) Interest expense related to sale of future royalties 35,949 Amortization of issuance costs related to sale of future royalties 305 Net liability related to sale of future royalties as of June 30, 2024 $ 533,754

Convertible Debt (Tables)

Convertible Debt (Tables)	6 Months Ended
	Jun. 30, 2024
1.75% Notes [Member]
Convertible Debt [Abstract]
Convertible Senior Notes	At June 30, 2024, we had the following 1.75% Notes outstanding (in millions except interest rate and price per share data): 1.75% Notes Outstanding principal balance $ 575.0 Unamortized debt issuance costs $ 11.4 Maturity date June 2028 Interest rate 1.75 % Effective interest rate 2.3 % Conversion price per share $ 53.73 Total shares of common stock subject to conversion 10.7
0% Notes [Member]
Convertible Debt [Abstract]
Convertible Senior Notes	At June 30, 2024, we had the following 0% 0% Notes Outstanding principal balance $ 632.5 Unamortized debt issuance costs $ 5.5 Maturity date April 2026 Interest rate 0 % Effective interest rate 0.5 % Conversion price per share $ 57.84 Effective conversion price per share with call spread $ 76.39 Total shares of common stock subject to conversion 10.9
0.125% Notes [Member]
Convertible Debt [Abstract]
Convertible Senior Notes	At June 30, 2024, we had the following 0.125% Notes outstanding with interest payable semi-annually (in millions except interest rate and price per share data): 0.125% Notes Outstanding principal balance $ 44.5 Unamortized debt issuance costs $ 0.1 Maturity date December 2024 Interest rate 0.125 % Effective interest rate 0.5 % Conversion price per share $ 83.28 Effective conversion price per share with call spread $ 123.38 Total shares of common stock subject to conversion, excluding shares related to 0.125 0.5

Organization and Basis of Pre_3

Organization and Basis of Presentation (Details)	6 Months Ended
	Jun. 30, 2024 Segment
Organization and Basis of Presentation [Abstract]
Number of operating segments	1

Supplemental Financial Data, In

Supplemental Financial Data, Inventories (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Inventory [Abstract]
Raw materials	$ 24,623	$ 22,794
Work in process	3,614	5,477
Finished goods	486	154
Total inventories	28,723	28,425
Clinical [Member]
Inventory [Abstract]
Raw materials	22,211	20,985
Commercial [Member]
Inventory [Abstract]
Raw materials	$ 2,412	$ 1,809

Supplemental Financial Data, Ac

Supplemental Financial Data, Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Accrued Liabilities [Abstract]
Clinical development expenses	$ 82,017	$ 105,967
In-licensing expenses	10,603	7,454
Commercial expenses	4,583	4,875
Other miscellaneous expenses	17,127	29,598
Total accrued liabilities	$ 114,330	$ 147,894

Revenues (Details)

Revenues (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2021 USD ($) Component PerformanceObligation
Revenues [Abstract]
Revenue	$ 225,250	$ 188,411	$ 344,748	$ 318,935
WAINUA (Eplontersen) Collaboration with AstraZeneca [Member]
Revenues [Abstract]
Upfront payment received					$ 200,000
Number of material components | Component					4
Number of performance obligations | PerformanceObligation					1
Transaction price					$ 200,000
Percentage of costs associated with ongoing global Phase 3 development program paid by AstraZeneca			55%
Commercial Revenue [Member]
Revenues [Abstract]
Revenue	72,036	77,897	$ 131,629	145,664
SPINRAZA Royalties [Member]
Revenues [Abstract]
Revenue	56,743	61,012	95,198	111,258
WAINUA Royalties [Member]
Revenues [Abstract]
Revenue	3,781	0	4,907	0
Other Commercial Revenue [Member]
Revenues [Abstract]
Revenue	11,512	16,885	31,524	34,406
TEGSEDI and WAYLIVRA Revenue, Net [Member]
Revenues [Abstract]
Revenue	8,192	10,655	16,820	17,133
Licensing and Other Royalty Revenue [Member]
Revenues [Abstract]
Revenue	3,320	6,230	14,704	17,273
Research and Development Revenue [Member]
Revenues [Abstract]
Revenue	153,214	110,514	213,119	173,271
Collaborative Agreement Revenue [Member]
Revenues [Abstract]
Revenue	141,524	91,013	190,870	129,347
WAINUA Joint Development Revenue [Member]
Revenues [Abstract]
Revenue	$ 11,690	$ 19,501	$ 22,249	$ 43,924

Collaborative Arrangements an_3

Collaborative Arrangements and Licensing Agreements, AstraZeneca (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($) Agreement	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) Agreement	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 225,250	$ 188,411	$ 344,748	$ 318,935
AstraZeneca [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements | Agreement	2		2
Revenue	$ 15,960	$ 59,501	$ 27,645	$ 83,926
Deferred contract revenue	$ 1,900		$ 1,900		$ 0
AstraZeneca [Member] | Revenue [Member] | Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage	7%	32%	8%	26%
AstraZeneca [Member] | Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received	$ 920,000		$ 920,000
WAINUA [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements | Agreement	1		1
Maximum amount of payments receivable over term of collaboration	$ 3,600,000		$ 3,600,000
Maximum amount of upfront payments over term of collaboration	200,000		200,000
Maximum amount of development milestone payments over term of collaboration	485,000		485,000
Maximum amount of sales milestone payments over term of collaboration	2,900,000		$ 2,900,000
WAINUA [Member] | Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Royalty percentage received on net sales of medicine			20%
Next payment to be achieved	$ 30,000		$ 30,000
Cardiovascular, Renal and Metabolic Diseases [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements | Agreement	1		1

Collaborative Arrangements an_4

Collaborative Arrangements and Licensing Agreements, Biogen (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 225,250	$ 188,411	$ 344,748	$ 318,935
Biogen [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	138,159	$ 97,402	197,395	$ 167,903
Deferred contract revenue	$ 241,800		$ 241,800		$ 307,400
Biogen [Member] | Revenue [Member] | Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage	61%	52%	57%	53%
Biogen [Member] | Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received	$ 3,900,000		$ 3,900,000
2013 Strategic Neurology [Member] | QALSODY [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Next payment to be achieved	10,000		10,000
Revenue	20,000
2012 Neurology [Member] | ION582 [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	30,000
2012 Neurology [Member] | IONIS-MAPT [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Next payment to be achieved	$ 25,000		$ 25,000

Collaborative Arrangements an_5

Collaborative Arrangements and Licensing Agreements, Otsuka (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($) PerformanceObligation	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) PerformanceObligation	Jun. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 225,250	$ 188,411	$ 344,748	$ 318,935
Otsuka [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Upfront payment received	20,000
Maximum amount of payments receivable over term of collaboration	290,000		290,000
Maximum amount of upfront payments over term of collaboration	85,000		85,000
Maximum amount of regulatory milestone payments over term of collaboration	65,000		65,000
Maximum amount of sales milestone payments over term of collaboration	140,000		140,000
Cumulative payments received	$ 85,000		$ 85,000
Number of separate performance obligations | PerformanceObligation	2		2
Transaction price	$ 20,000		$ 20,000
Revenue	18,905	$ 0	19,691	$ 0
Deferred contract revenue	$ 8,800		$ 8,800		$ 8,500
Otsuka [Member] | Revenue [Member] | Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage	8%	0%	6%	0%
Otsuka [Member] | Maximum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Royalty percentage received on net sales of medicine			30%
Otsuka [Member] | Donidalorsen [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Next payment to be achieved	$ 15,000		$ 15,000
Otsuka [Member] | License of Donidalorsen [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Transaction price	17,500		17,500
Revenue	17,500
Otsuka [Member] | R&D Services for Donidalorsen [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Transaction price	$ 2,500		$ 2,500

Collaborative Arrangements an_6

Collaborative Arrangements and Licensing Agreements, Roche (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024 USD ($) Agreement	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) Agreement	Jun. 30, 2023 USD ($)	Jul. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue	$ 225,250	$ 188,411	$ 344,748	$ 318,935
Roche [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements | Agreement	3		3
Revenue	$ 11,089	$ 5,754	$ 22,595	$ 8,121
Deferred contract revenue	$ 15,000		$ 15,000			$ 36,700
Roche [Member] | Revenue [Member] | Strategic Partner [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Concentration percentage	5%	3%	7%	3%
Roche [Member] | Minimum [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Cumulative payments received	$ 345,000		$ 345,000
HD [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements | Agreement	1		1
IONIS-FB-L for Complement-Mediated Diseases [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements | Agreement	1		1
IONIS-FB-L for Complement-Mediated Diseases [Member] | Subsequent Event [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Maximum amount of payments receivable over term of collaboration					$ 430,000
Maximum amount of license fees over term of collaboration					35,000
Maximum amount of development milestone payments over term of collaboration					25,000
Maximum amount of regulatory milestone payments over term of collaboration					90,000
Maximum amount of sales milestone payments over term of collaboration					280,000
Next payment to be achieved					$ 23,500
RNA-targeted Programs for AD and HD [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Number of collaboration agreements | Agreement	1		1

Basic and Diluted Net Loss Pe_3

Basic and Diluted Net Loss Per Share (Details)	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
1.75% Notes [Member]
Diluted Net Loss per Share [Abstract]
Interest rate on convertible senior notes	1.75%	1.75%	1.75%
0% Notes [Member]
Diluted Net Loss per Share [Abstract]
Interest rate on convertible senior notes	0%	0%	0%
0.125% Notes [Member]
Diluted Net Loss per Share [Abstract]
Interest rate on convertible senior notes	0.125%	0.125%	0.125%

Investments, Contract Maturity

Investments, Contract Maturity of Available-for-Sale Securities (Details)	6 Months Ended
	Jun. 30, 2024
Contract Maturity of Available-for-Sale Securities [Abstract]
One year or less	75%
After one year but within two years	21%
After two years but within three and a half years	4%
Total	100%
Maximum contract maturity period, range 1	1 year
Maximum contract maturity period, range 2	2 years
Maximum contract maturity period, range 3	3 years 6 months
Percentage of available-for-sale securities with a maturity of less than two years	96%

Investments, Summary of Investm

Investments, Summary of Investments (Details) $ in Thousands		6 Months Ended
		Jun. 30, 2024 USD ($) Company	Dec. 31, 2023 USD ($)
Ownership Interests in Private and Public Companies [Abstract]
Number of private companies in which there is an equity ownership interest of less than 20% | Company		7
Number of public companies in which there is an equity ownership interest of less than 20% | Company		3
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost		$ 1,343,698	$ 1,316,219
Gross unrealized gains		67	415
Gross unrealized losses		(3,026)	(5,238)
Estimated fair value		1,340,739	1,311,396
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		462,896	651,628
Gross unrealized gains		275	3,063
Gross unrealized losses		(2,334)	(1,197)
Estimated fair value		460,837	653,494
Available-for-sale Debt Securities [Abstract]
Amortized cost		1,806,594	1,967,847
Gross unrealized gains		342	3,478
Gross unrealized losses		(5,360)	(6,435)
Estimated fair value		1,801,576	1,964,890
Equity Securities [Abstract]
Amortized cost		35,012	35,012
Gross unrealized gains		25,335	25,237
Gross unrealized losses		(12,470)	(10,957)
Estimated fair value		47,877	49,292
Available-for-sale Debt and Equity Securities [Abstract]
Amortized cost		1,841,606	2,002,859
Gross unrealized gains		25,677	28,715
Gross unrealized losses		(17,830)	(17,392)
Estimated fair value		1,849,453	2,014,182
Corporate Debt Securities [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost	[1]	552,837	559,967
Gross unrealized gains		36	157
Gross unrealized losses		(1,569)	(2,625)
Estimated fair value		551,304	557,499
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		218,639	243,151
Gross unrealized gains		191	1,270
Gross unrealized losses		(874)	(692)
Estimated fair value		217,956	243,729
Debt Securities Issued by U.S. Government Agencies [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost		121,781	224,711
Gross unrealized gains		5	64
Gross unrealized losses		(310)	(611)
Estimated fair value		121,476	224,164
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		115,349	110,138
Gross unrealized gains		72	547
Gross unrealized losses		(317)	(21)
Estimated fair value		115,104	110,664
Debt Securities Issued by the U.S. Treasury [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost	[1]	650,997	513,784
Gross unrealized gains		12	152
Gross unrealized losses		(1,105)	(1,889)
Estimated fair value		649,904	512,047
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		127,240	294,873
Gross unrealized gains		12	1,239
Gross unrealized losses		(1,135)	(480)
Estimated fair value		126,117	295,632
Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Available-for-sale Debt Securities with Maturity of One Year or Less [Abstract]
Amortized cost		18,083	17,757
Gross unrealized gains		14	42
Gross unrealized losses		(42)	(113)
Estimated fair value		18,055	17,686
Available-for-sale Debt Securities with Maturity of More Than One Year [Abstract]
Amortized cost		1,668	3,466
Gross unrealized gains		0	7
Gross unrealized losses		(8)	(4)
Estimated fair value		1,660	3,469
Publicly Traded Equity Securities [Member]
Equity Securities [Abstract]
Amortized cost	[2]	11,897	11,897
Gross unrealized gains		334	236
Gross unrealized losses		(5,377)	(5,832)
Estimated fair value		6,854	6,301
Available-for-sale Debt and Equity Securities [Abstract]
Unrealized gain on equity securities		600
Privately Held Equity Securities [Member]
Equity Securities [Abstract]
Amortized cost	[3]	23,115	23,115
Gross unrealized gains		25,001	25,001
Gross unrealized losses		(7,093)	(5,125)
Estimated fair value		41,023	$ 42,991
Available-for-sale Debt and Equity Securities [Abstract]
Unrealized loss on equity securities		$ (2,000)
[1]Includes investments classified as cash equivalents in our condensed consolidated balance sheets.[2]Our publicly traded equity securities are included in other current assets. We recognize publicly traded equity securities at fair value. In the six months ended June 30, 2024, we recorded a $0.6 million net unrealized gain in our condensed consolidated statements of operations related to changes in the fair value of our investments in publicly traded companies.[3] Our privately held equity securities are included in deposits and other assets. We recognize our privately held equity securities at . In the , we recorded a loss of $ million in our condensed consolidated statements of operations related to changes in the fair value of our investments in privately held companies.

Investments, Investments Tempor

Investments, Investments Temporarily Impaired (Details) $ in Thousands	Jun. 30, 2024 USD ($) Investment
Temporarily Impaired Investments [Abstract]
Number of investments | Investment	664
Estimated Fair Value [Abstract]
Less than 12 months of temporary impairment	$ 1,260,824
More than 12 months of temporary impairment	331,607
Total temporary impairment	1,592,431
Unrealized Losses [Abstract]
Less than 12 months of temporary impairment	(2,522)
More than 12 months of temporary impairment	(2,838)
Total temporary impairment	$ (5,360)
Corporate Debt Securities [Member]
Temporarily Impaired Investments [Abstract]
Number of investments | Investment	440
Estimated Fair Value [Abstract]
Less than 12 months of temporary impairment	$ 517,394
More than 12 months of temporary impairment	142,390
Total temporary impairment	659,784
Unrealized Losses [Abstract]
Less than 12 months of temporary impairment	(1,155)
More than 12 months of temporary impairment	(1,288)
Total temporary impairment	$ (2,443)
Debt Securities Issued by U.S. Government Agencies [Member]
Temporarily Impaired Investments [Abstract]
Number of investments | Investment	108
Estimated Fair Value [Abstract]
Less than 12 months of temporary impairment	$ 173,618
More than 12 months of temporary impairment	25,892
Total temporary impairment	199,510
Unrealized Losses [Abstract]
Less than 12 months of temporary impairment	(482)
More than 12 months of temporary impairment	(145)
Total temporary impairment	$ (627)
Debt Securities Issued by the U.S. Treasury [Member]
Temporarily Impaired Investments [Abstract]
Number of investments | Investment	71
Estimated Fair Value [Abstract]
Less than 12 months of temporary impairment	$ 561,363
More than 12 months of temporary impairment	154,006
Total temporary impairment	715,369
Unrealized Losses [Abstract]
Less than 12 months of temporary impairment	(862)
More than 12 months of temporary impairment	(1,378)
Total temporary impairment	$ (2,240)
Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Temporarily Impaired Investments [Abstract]
Number of investments | Investment	45
Estimated Fair Value [Abstract]
Less than 12 months of temporary impairment	$ 8,449
More than 12 months of temporary impairment	9,319
Total temporary impairment	17,768
Unrealized Losses [Abstract]
Less than 12 months of temporary impairment	(23)
More than 12 months of temporary impairment	(27)
Total temporary impairment	$ (50)

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands		Jun. 30, 2024		Dec. 31, 2023		Jun. 30, 2023
Fair Value Measurements [Abstract]
Available-for-sale securities		$ 1,801,576		$ 1,964,890
Equity securities		$ 47,877		$ 49,292
1.75% Notes [Member]
Fair Value Measurements [Abstract]
Interest rate on convertible senior notes		1.75%		1.75%		1.75%
0% Notes [Member]
Fair Value Measurements [Abstract]
Interest rate on convertible senior notes		0%		0%		0%
0.125% Notes [Member]
Fair Value Measurements [Abstract]
Interest rate on convertible senior notes		0.125%		0.125%		0.125%
Publicly Traded Equity Securities [Member]
Fair Value Measurements [Abstract]
Equity securities		$ 6,854		$ 6,301
Recurring Basis [Member]
Fair Value Measurements [Abstract]
Cash equivalents	[1]	212,489		185,424
Total		2,020,919		2,156,615
Recurring Basis [Member] | Corporate Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		769,260	[2]	801,228	[3]
Recurring Basis [Member] | Corporate Debt Securities [Member] | Cash and Cash Equivalents [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		16,900		33,000
Recurring Basis [Member] | Debt Securities Issued by U.S. Government Agencies [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities	[4]	236,580		334,828
Recurring Basis [Member] | Debt Securities Issued by the U.S. Treasury [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities	[4]	776,021		807,679
Recurring Basis [Member] | Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities	[4]	19,715		21,155
Recurring Basis [Member] | Publicly Traded Equity Securities [Member] | Other Current Assets [Member]
Fair Value Measurements [Abstract]
Equity securities	[5]	6,854		6,301
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Fair Value Measurements [Abstract]
Cash equivalents		212,489		185,424
Total		995,364		999,404
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Corporate Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Debt Securities Issued by U.S. Government Agencies [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Debt Securities Issued by the U.S. Treasury [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		776,021		807,679
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Publicly Traded Equity Securities [Member]
Fair Value Measurements [Abstract]
Equity securities		6,854		6,301
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value Measurements [Abstract]
Cash equivalents		0		0
Total		1,025,555		1,157,211
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | 1.75% Notes [Member]
Fair Value Measurements [Abstract]
Convertible notes		634,400		661,100
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | 0% Notes [Member]
Fair Value Measurements [Abstract]
Convertible notes		649,600		667,800
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | 0.125% Notes [Member]
Fair Value Measurements [Abstract]
Convertible notes		43,400		42,400
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate Debt Securities [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		769,260		801,228
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Debt Securities Issued by U.S. Government Agencies [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		236,580		334,828
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Debt Securities Issued by the U.S. Treasury [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		0		0
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Debt Securities Issued by States of the U.S. and Political Subdivisions of the States [Member]
Fair Value Measurements [Abstract]
Available-for-sale securities		19,715		21,155
Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Publicly Traded Equity Securities [Member]
Fair Value Measurements [Abstract]
Equity securities		$ 0		$ 0
[1]Included in cash and cash equivalents.[2]$16.9 million was included in cash and cash equivalents, with the difference included in short-term investments.[3]$33.0 million was included in cash and cash equivalents, with the difference included in short-term investments.[4]Included in short-term investments.[5]Included in other current assets.

Stock-based Compensation Expe_3

Stock-based Compensation Expense (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	$ 30,728	$ 26,561	$ 62,068	$ 53,510
Cost of Sales [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	246	118	450	237
Research, Development and Patent Expense [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	22,766	19,249	44,991	38,816
Selling, General and Administrative Expense [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	7,716	$ 7,194	16,627	$ 14,457
Stock Options [Member]
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation expense related to non-vested stock options	61,600		$ 61,600
Weighted average period for recognition			1 year 3 months 18 days
Stock Options [Member] | Employees [Member]
Weighted-Average Assumptions [Abstract]
Risk-free interest rate			4.10%	3.60%
Dividend yield			0%	0%
Volatility			43.90%	47.30%
Expected life			6 years 3 months 18 days	6 years 3 months 18 days
ESPP [Member]
Weighted-Average Assumptions [Abstract]
Risk-free interest rate			5.30%	5.20%
Dividend yield			0%	0%
Volatility			38.40%	36.70%
Expected life			6 months	6 months
RSUs [Member]
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost related to non-vested units	96,700		$ 96,700
Weighted average period for recognition			1 year 7 months 6 days
RSUs [Member] | Employees [Member]
RSUs and PRSUs [Abstract]
Weighted-average grant date fair value (in dollars per share)			$ 52.6	$ 39.5
PRSUs [Member]
Unrecognized Compensation Expense [Abstract]
Unrecognized compensation cost related to non-vested units	$ 13,800		$ 13,800
Weighted average period for recognition			1 year 10 months 24 days
PRSUs [Member] | Executive Officers [Member]
RSUs and PRSUs [Abstract]
Weighted-average grant date fair value (in dollars per share)			$ 78.41	$ 58.99
PRSUs [Member] | Granted in 2024 [Member]
RSUs and PRSUs [Abstract]
Vesting percentage			100%
Vesting period			3 years
Number of units guaranteed to vest (in shares)			0
PRSUs [Member] | Granted in 2024 [Member] | Minimum [Member]
RSUs and PRSUs [Abstract]
Percentage of units guaranteed to vest			0%
PRSUs [Member] | Granted in 2024 [Member] | Maximum [Member]
RSUs and PRSUs [Abstract]
Percentage of units guaranteed to vest			200%
PRSUs [Member] | Granted in 2023 [Member] | Executive Officers [Member]
RSUs and PRSUs [Abstract]
Vesting percentage			100%
Vesting period			3 years
Number of units guaranteed to vest (in shares)			0
PRSUs [Member] | Granted in 2023 [Member] | Executive Officers [Member] | Minimum [Member]
RSUs and PRSUs [Abstract]
Percentage of units guaranteed to vest			0%
PRSUs [Member] | Granted in 2023 [Member] | Executive Officers [Member] | Maximum [Member]
RSUs and PRSUs [Abstract]
Percentage of units guaranteed to vest			200%

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Taxes [Abstract]
Income tax expense	$ 64	$ 7,842	$ 140	$ 19,223

Liability Related to Sale of _3

Liability Related to Sale of Future Royalties (Details) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended		12 Months Ended
	Jan. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Royalty Revenue Monetization [Abstract]
Proceeds from sale of future royalties in January 2023		$ 0	$ 500,000
Issuance costs related to sale of future royalties		0	(10,434)
Royalty payments to Royalty Pharma		(16,236)	(12,562)
Interest expense related to sale of future royalties		35,949	$ 32,915
Net liability related to sale of future royalties		533,754		$ 513,736
Royalty Purchase Agreement [Member]
Royalty Revenue Monetization [Abstract]
Upfront payment received	$ 500,000
Maximum amount of payments receivable for additional milestones		$ 625,000
Effective interest rate		13.50%
Proceeds from sale of future royalties in January 2023	$ 500,000
Issuance costs related to sale of future royalties				(10,434)
Royalty payments to Royalty Pharma		$ (16,236)		(44,628)
Interest expense related to sale of future royalties		35,949		68,238
Amortization of issuance costs related to sale of future royalties		305		560
Net liability related to sale of future royalties		533,754		$ 513,736
Royalty Purchase Agreement [Member] | SPINRAZA [Member]
Royalty Revenue Monetization [Abstract]
Maximum amount of annual sales on which royalty payments are paid		$ 1,500,000
Royalty Purchase Agreement [Member] | SPINRAZA [Member] | Minimum [Member]
Royalty Revenue Monetization [Abstract]
Percentage of royalty payments paid on annual sales of medicine		25%
Maximum royalty payments made before royalty interest reverts back		$ 475,000
Royalty Purchase Agreement [Member] | SPINRAZA [Member] | Maximum [Member]
Royalty Revenue Monetization [Abstract]
Percentage of royalty payments paid on annual sales of medicine		45%
Maximum royalty payments made before royalty interest reverts back		$ 550,000
Royalty Purchase Agreement [Member] | Pelacarsen [Member]
Royalty Revenue Monetization [Abstract]
Percentage of royalty payments paid on annual sales of medicine		25%

Convertible Debt (Details)

Convertible Debt (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2021	Dec. 31, 2019
Convertible Debt [Abstract]
Repurchase of convertible senior notes	$ 0	$ 420,158
1.75% Notes [Member]
Convertible Debt [Abstract]
Face amount of offering			$ 575,000
Repurchase of convertible senior notes			$ 488,200
Outstanding principal balance	575,000
Unamortized debt issuance costs	$ 11,400
Maturity date	Jun. 30, 2028
Interest rate	1.75%	1.75%	1.75%
Effective interest rate	2.30%
Conversion price per share (in dollars per share)	$ 53.73
Total shares of common stock subject to conversion (in shares)	10.7
Percentage of principal amount used as purchase price upon occurrence of fundamental change	100%
0% Notes [Member]
Convertible Debt [Abstract]
Outstanding principal balance	$ 632,500
Unamortized debt issuance costs	$ 5,500
Maturity date	Apr. 30, 2026
Interest rate	0%	0%	0%
Effective interest rate	0.50%
Conversion price per share (in dollars per share)	$ 57.84
Effective conversion price per share with call spread (in dollars per share)	$ 76.39
Total shares of common stock subject to conversion (in shares)	10.9
Cost of call spread				$ 46,900
Purchase of note hedges				136,700
Proceeds from issuance of warrants				$ 89,800
Percentage of principal amount used as purchase price upon occurrence of fundamental change	100%
0.125% Notes [Member]
Convertible Debt [Abstract]
Repurchase of convertible senior notes			$ 504,400
Outstanding principal balance	$ 44,500
Unamortized debt issuance costs	$ 100
Maturity date	Dec. 31, 2024
Interest rate	0.125%	0.125%	0.125%
Effective interest rate	0.50%
Conversion price per share (in dollars per share)	$ 83.28
Effective conversion price per share with call spread (in dollars per share)	$ 123.38
Total shares of common stock subject to conversion (in shares)	0.5
Cost of call spread					$ 52,600
Purchase of note hedges					108,700
Proceeds from issuance of warrants					$ 56,100
Percentage of principal amount used as purchase price upon occurrence of fundamental change	100%