Inovio Pharmaceuticals (INO) 10-K 12 Mar 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 11, 2020	Jun. 28, 2019
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Registrant Name	INOVIO PHARMACEUTICALS, INC.
Entity Central Index Key	0001055726
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		145,803,086
Entity Well-known Seasoned Issuer	No
Entity Public Float			$ 279,656,181
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 22,196,097	$ 23,693,633
Short-term investments	67,338,017	57,538,852
Accounts receivable	700,073	3,316,361
Accounts receivable from affiliated entities	1,332,044	738,583
Prepaid expenses and other current assets	1,584,598	1,406,590
Prepaid expenses and other current assets from affiliated entities	1,050,140	1,120,805
Total current assets	94,200,969	87,814,824
Fixed assets, net	12,773,017	15,949,014
Investments in affiliated entities	6,315,356	9,405,913
Intangible assets, net	3,693,851	4,760,145
Goodwill	10,513,371	10,513,371
Operating lease right-of-use assets	13,783,009
Other assets	2,672,024	2,669,998
Total assets	143,951,597	131,113,265
Current liabilities:
Accounts payable and accrued expenses	18,237,258	23,134,733
Accounts payable and accrued expenses due to affiliated entities	729,729	977,792
Accrued clinical trial expenses	4,049,727	5,671,764
Deferred revenue	92,353	223,577
Deferred revenue from affiliated entities	31,775	33,575
Deferred rent	0	1,065,387
Operating lease liability	2,074,842	0
Grant funding liability	6,065,212	4,165,848
Grant funding liability from affiliated entities	708,425	27,083
Total current liabilities	31,989,321	35,299,759
Deferred revenue, net of current portion	101,567	150,793
Derivative liability	8,819,023	0
Deferred rent, net of current portion	0	8,518,207
Operating lease liability, net of current portion	20,409,922
Deferred tax liabilities	32,046	24,766
Grant funding liability from affiliated entity, net of current portion	135,000	0
Other liabilities	36,943	87,333
Total liabilities	138,546,739	44,080,858
Commitments and contingencies
Inovio Pharmaceuticals, Inc. stockholders’ equity:
Preferred stock—par value $0.001; Authorized shares: 10,000,000, issued and outstanding shares: 23 at December 31, 2019 and December 31, 2018	0	0
Common stock—par value $0.001; Authorized shares: 600,000,000 at December 31, 2019 and December 31, 2018, issued and outstanding: 101,361,034 at December 31, 2019 and 97,225,810 at December 31, 2018	101,361	97,226
Additional paid-in capital	742,646,785	707,794,215
Accumulated deficit	(739,785,655)	(620,426,436)
Accumulated other comprehensive income (loss)	472,608	(528,867)
Total Inovio Pharmaceuticals, Inc. stockholders’ equity	3,435,099	86,936,138
Non-controlling interest	1,969,759	96,269
Total stockholders’ equity	5,404,858	87,032,407
Total liabilities and stockholders’ equity	143,951,597	131,113,265
6.50% Convertible Senior Notes Due 2024
Current liabilities:
Convertible debt	64,180,325	0
Convertible Bonds
Current liabilities:
Convertible debt	$ 12,842,592	$ 0

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value ($ per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (shares)	10,000,000	10,000,000
Preferred stock, shares issued (shares)	23	23
Preferred stock, shares outstanding (shares)	23	23
Common stock, par value ($ per share)	$ 0.001	$ 0.001
Common stock, shares authorized (shares)	600,000,000	600,000,000
Common stock, shares issued (shares)	101,361,034	97,225,810
Common stock, shares (shares)	101,361,034	97,225,810

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Total revenues	$ 4,111,930	$ 30,481,897	$ 42,220,086
Operating expenses:
Research and development	88,017,319	95,257,876	98,572,618
General and administrative	27,203,156	29,315,159	28,290,369
Gain on sale of assets	0	0	(1,000,000)
Total operating expenses	115,220,475	124,573,035	125,862,987
Loss from operations	(111,108,545)	(94,091,138)	(83,642,901)
Other income (expense):
Interest income	2,605,981	2,264,747	1,836,451
Interest expense	(7,948,539)	0	(25,933)
Change in fair value of common stock warrants	0	360,795	806,819
Change in fair value of derivative liability	(1,763,652)	0	0
Loss on investment in affiliated entities	(3,090,557)	(1,988,567)	(6,982,664)
Other income (expense), net	496,200	(1,343,856)	(197,544)
Net loss before income tax benefit/(provision for income tax)	(120,809,112)	(94,798,019)	(88,205,772)
Income tax benefit (provision for income taxes)	257,335	(2,169,811)	0
Net loss	(120,551,777)	(96,967,830)	(88,205,772)
Net loss attributable to non-controlling interest	1,192,558	0	0
Net loss attributable to Inovio Pharmaceuticals, Inc.	$ (119,359,219)	$ (96,967,830)	$ (88,205,772)
Net loss per share attributable to Inovio Pharmaceuticals, Inc. stockholders
Basic ($ per share)	$ (1.21)	$ (1.05)	$ (1.08)
Diluted ($ per share)	$ (1.21)	$ (1.05)	$ (1.09)
Weighted average number of common shares outstanding
Basic (shares)	98,717,999	92,539,997	81,777,493
Diluted (shares)	98,717,999	92,539,997	81,918,022
Revenue under collaborative research and development arrangements
Revenues:
Total revenues	$ 3,636,945	$ 29,860,785	$ 28,407,388
Revenue under collaborative research and development arrangements with affiliated entities
Revenues:
Total revenues	235,649	449,524	765,828
Miscellaneous revenue, including from affiliated entities
Revenues:
Total revenues	237,536	171,588	10,474,539
Grants and miscellaneous revenue from affiliated entity
Revenues:
Total revenues	$ 1,800	$ 0	$ 2,572,331

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (120,551,777)	$ (96,967,830)	$ (88,205,772)
Other comprehensive income (loss):
Unrealized loss on investment in affiliated entity, net of tax	0	0	(1,452,431)
Unrealized gain (loss) on short-term investments, net of tax	1,001,475	(180,496)	7,458
Comprehensive loss	(119,550,302)	(97,148,326)	(89,650,745)
Comprehensive loss attributable to non-controlling interest	1,192,558	0	0
Comprehensive loss attributable to Inovio Pharmaceuticals, Inc.	$ (118,357,744)	$ (97,148,326)	$ (89,650,745)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($)	Total	Preferred stock	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)	Non- controlling interest
Beginning balance (shares) at Dec. 31, 2016		23	74,062,370
Beginning balance at Dec. 31, 2016	$ 123,378,420	$ 0	$ 74,062	$ 556,718,356	$ (434,838,235)	$ 1,327,968	$ 96,269
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash, net of financing costs (shares)			15,437,406
Issuance of common stock for cash, net of financing costs of $4.9 million	94,347,922		$ 15,437	94,332,485
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (shares)			857,868
Exercise of stock options for cash and vesting of RSUs, net of tax payments	1,342,250		$ 859	1,341,391
Stock-based compensation	13,070,962			13,070,962
Net loss attributable to common stockholders	(88,205,772)				(88,205,772)
Unrealized gain on short-term investments, net of tax	7,458					7,458
Unrealized loss on investment in affiliated entity, net of tax	(1,452,431)					(1,452,431)
Ending balance (shares) at Dec. 31, 2017		23	90,357,644
Ending balance at Dec. 31, 2017	142,488,809	$ 0	$ 90,358	665,775,504	(523,356,317)	(117,005)	96,269
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash, net of financing costs (shares)			5,669,025
Issuance of common stock for cash, net of financing costs of $4.9 million	29,227,776		$ 5,669	29,222,107
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (shares)			1,199,141
Exercise of stock options for cash and vesting of RSUs, net of tax payments	1,809,526		$ 1,199	1,808,327
Stock-based compensation	10,654,622			10,988,277	(333,655)
Net loss attributable to common stockholders	(96,967,830)				(96,967,830)
Unrealized gain on short-term investments, net of tax	(180,496)					(180,496)
Unrealized loss on investment in affiliated entity, net of tax	0
Ending balance (shares) at Dec. 31, 2018		23	97,225,810
Ending balance at Dec. 31, 2018	87,032,407	$ 0	$ 97,226	707,794,215	(620,426,436)	(528,867)	96,269
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock for cash, net of financing costs (shares)			3,340,678
Issuance of common stock for cash, net of financing costs of $4.9 million	9,089,009		$ 3,340	9,085,669
Exercise of stock options and warrants for cash and vesting of RSUs, net of tax payments (shares)			794,546
Exercise of stock options for cash and vesting of RSUs, net of tax payments	(780,405)		$ 795	(781,200)
Equity component of issuance of convertible notes	15,752,698			15,752,698
Stock-based compensation	10,901,320			10,795,403			105,917
Acquisition of non-controlling interest in Geneos, net	2,960,131						2,960,131
Net loss attributable to common stockholders	(120,551,777)				(119,359,219)		(1,192,558)
Unrealized gain on short-term investments, net of tax	1,001,475					1,001,475
Unrealized loss on investment in affiliated entity, net of tax	0
Ending balance (shares) at Dec. 31, 2019		23	101,361,034
Ending balance at Dec. 31, 2019	$ 5,404,858	$ 0	$ 101,361	$ 742,646,785	$ (739,785,655)	$ 472,608	$ 1,969,759

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Statement of Stockholders' Equity [Abstract]
Issuance of common stock for cash, financing costs	$ 4.9

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (120,551,777)	$ (96,967,830)	$ (88,205,772)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	3,598,388	3,747,183	1,850,376
Amortization of intangible assets	1,066,294	1,249,584	1,618,665
Amortization of operating lease right-of-use assets	851,760
Change in fair value of common stock warrants	0	(360,795)	(806,819)
Change in fair value of derivative liability	1,763,652	0	0
Stock-based compensation	10,901,320	10,654,622	13,070,962
Non-cash interest expense	5,230,954	0	0
Amortization of premiums on investments	1,962	72,561	319,845
Deferred taxes	5,397	0	(150,027)
Loss (gain) on short-term investments	(476,368)	1,342,005	215,423
Loss on disposal of fixed assets	5,889	14,529	0
Loss on equity investment in affiliated entities	3,090,557	1,988,567	6,982,664
Gain on sale of intangible assets	0	0	(1,000,000)
Tax benefit from other unrealized gains on short-term investments	(266,215)	0	0
Unrealized transaction loss on foreign-currency denominated debt	471,172	0	0
Changes in operating assets and liabilities:
Accounts receivable	2,616,288	2,686,844	9,818,306
Accounts receivable from affiliated entities	(593,461)	(251,964)	261,736
Prepaid expenses and other current assets	(178,008)	1,194,316	(851,847)
Prepaid expenses and other current assets from affiliated entities	70,665	725,202	(333,583)
Other assets	(2,026)	(30,644)	(526,207)
Accounts payable and accrued expenses	(4,337,829)	550,407	2,829,807
Accrued clinical trial expenses	(1,622,037)	(2,940,128)	2,243,503
Accounts payable and accrued expenses due to affiliated entities	(248,063)	50,849	(145,636)
Deferred revenue	(180,450)	(1,016,836)	(13,689,322)
Deferred revenue from affiliated entities	(1,800)	(140,535)	(319,876)
Deferred rent	0	(398,357)	3,608,881
Operating lease right-of-use assets and liabilities, net	(1,733,599)
Grant funding liability	1,899,364	4,165,848	0
Grant funding liability from affiliated entities	816,342	27,083	0
Other liabilities	(48,507)	87,333	0
Net cash used in operating activities	(97,850,136)	(73,550,156)	(63,208,921)
Cash flows from investing activities:
Purchases of investments	(100,950,301)	(88,155,046)	(95,700,144)
Proceeds from sale of or maturity of investments	92,893,232	132,659,976	77,162,902
Purchases of capital assets	(987,926)	(2,085,022)	(10,293,902)
Proceeds from sale of intangible assets	0	0	1,000,000
Net cash (used in) provided by investing activities	(9,044,995)	42,419,908	(27,831,144)
Cash flows from financing activities:
Proceeds from issuances of convertible senior notes and convertible bonds	97,443,617	0	0
Costs related to issuances of convertible senior notes and convertible bonds	(3,314,757)	0	0
Proceeds from issuance of common stock and warrants, net of issuance costs	9,089,010	29,227,776	94,347,922
Proceeds from stock option and warrant exercises, net of tax payments	0	1,809,526	1,342,250
Taxes paid related to net share settlement of equity awards, net of proceeds from option exercises	(780,406)	0	0
Acquisition of non-controlling interest	2,960,131	0	0
Net cash provided by financing activities	105,397,595	31,037,302	95,690,172
Increase (decrease) in cash and cash equivalents	(1,497,536)	(92,946)	4,650,107
Cash and cash equivalents, beginning of period	23,693,633	23,786,579	19,136,472
Cash and cash equivalents, end of period	22,196,097	23,693,633	23,786,579
Supplemental disclosure:
Amounts accrued for purchases of property and equipment	0	559,646	1,254,117
Interest paid	2,717,585	0	0
Equity component of issuance of convertible notes	15,752,698	$ 0	$ 0
Right-of-use assets obtained in exchange for lease obligations	$ 14,634,769

The Company

The Company	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company	The Company Inovio Pharmaceuticals, Inc. (the “Company” or “Inovio”), is a biotechnology company focused on rapidly bringing to market precisely designed DNA medicines to treat, cure, and protect people from diseases associated with human papillomavirus (HPV), cancer, and infectious diseases. The Company's DNA medicine pipeline is comprised of three types of candidates, DNA vaccines, DNA immunotherapies and DNA encoded monoclonal antibodies (dMABs). In clinical trials, Inovio has demonstrated that a DNA medicine can be delivered directly into cells in the body via its proprietary smart device to consistently activate robust and fully functional T cell and antibody responses against targeted cancers and pathogens. The Company's novel DNA medicines are made using its proprietary SynCon ® technology that creates optimized plasmids, which are circular strands of DNA that can produce antigens independently inside a cell to help the person's immune system recognize and destroy cancerous or virally infected cells. Inovio's hand-held CELLECTRA ® smart delivery devices provide optimized uptake of its DNA medicines within the cell, overcoming a key limitation of other DNA-based technology approaches. Human data to date have shown a favorable safety profile of Inovio’s DNA medicines delivered directly into cells in the body using the CELLECTRA ® smart delivery device in more than 6,000 administrations across more than 2,000 patients. Inovio's corporate strategy is to advance, protect, and provide its novel DNA medicines to meet urgent and emerging global health needs. The Company continues to advance and validate an array of DNA medicine candidates that target HPV-related diseases, cancer, and infectious diseases. The Company aims to advance these candidates through commercialization and continue to leverage third-party resources through collaborations and partnerships, including product license agreements. The Company's partners and collaborators include ApolloBio Corp., AstraZeneca, Beijing Advaccine, The Bill & Melinda Gates Foundation, Coalition for Epidemic Preparedness Innovations (CEPI), Defense Advanced Research Projects Agency (DARPA), GeneOne Life Science, HIV Vaccines Trial Network, the U.S. Defense Threat Reduction Agency’s Medical CBRN Defense Consortium (MCDC), National Cancer Institute, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Plumbline Life Sciences, Regeneron Pharmaceuticals, Inc., Roche/Genentech, the University of Pennsylvania, the Walter Reed Army Institute of Research, and The Wistar Institute. The Company and its collaborators are currently conducting or planning clinical studies of its DNA medicines for HPV-associated precancers, including cervical, vulvar, and anal dysplasia; HPV-associated cancers, including head & neck, cervical, anal, penile, vulvar, and vaginal; other HPV-associated disorders, such as recurrent respiratory papillomatosis (RRP); glioblastoma multiforme (GBM); prostate cancer; HIV; Ebola; Middle East Respiratory Syndrome (MERS); Lassa fever; Zika virus; and the COVID-19 virus (coronavirus). Inovio was incorporated in Delaware in June 2001 and has its principal executive offices in Plymouth Meeting, Pennsylvania.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation Inovio incurred a net loss attributable to common stockholders of $119.4 million for the year ended December 31, 2019 . Inovio had working capital of $62.2 million and an accumulated deficit of $739.8 million as of December 31, 2019 . The Company has incurred losses in each year since its inception and expects to continue to incur significant expenses and operating losses for the foreseeable future in connection with the research and preclinical and clinical development of its product candidates. During the year ended December 31, 2019, the Company received net proceeds of $75.7 million from a private placement of $78.5 million aggregate principal amount of its 6.50% convertible senior notes due 2024 (the “Notes”), net proceeds of $14.5 million from the private placement of 18 billion Korean Won (KRW) (approximately USD $15.0 million based on the exchange rate on the date of issuance) aggregate principal amount of its 1.0% convertible bonds due August 2024 (the "August 2019 Bonds"), net proceeds of $4.0 million from the private placement of 4.7 billion KRW (approximately USD $4.1 million based on the exchange rate on the date of issuance) aggregate principal amount of its 1.0% convertible bonds due December 2024 (the "December 2019 Bonds" and, collectively with the August 2019 Bonds, the “Bonds”) and net proceeds of $9.1 million from sales of common stock under its At-the-Market Equity Offering Sales Agreement with Stifel, Nicolaus & Company (the “Sales Agreement”). As described in Note 19 below, the Sales Agreement was amended subsequent to December 31, 2019. From January 1, 2020 through March 11, 2020 , the Company sold 43,148,952 shares of common stock under the Sales Agreement, as amended, for net proceeds of $208.2 million. These proceeds, in addition to the Company’s cash, cash equivalents and short-term investments of $ 89.5 million and long-term investments of $ 6.3 million as of December 31, 2019 , are sufficient to support the Company's operations for a period of at least 12 months from the date it issued these financial statements. In order to continue to fund future research and development activities, the Company will need to seek additional capital. This may occur through strategic alliance and licensing arrangements and/or future public or private debt or equity financings including use of its Sales Agreement. However, sufficient funding may not be available in the future, or if available, may be on terms that significantly dilute or otherwise adversely affect the rights of existing stockholders. If adequate funds are not available, the Company may need to delay, reduce the scope of or put on hold one or more of its clinical and/or preclinical programs. In July 2019, the Company announced a strategic organizational restructuring. In order to reduce operating expenses and conserve cash resources, the Company reduced its workforce by approximately 28% and discontinued its Phase 1/2 clinical trial of its immuno-oncology product candidate INO-5401 in patients with advanced bladder cancer. In the third quarter of 2019, the Company incurred a personnel-related restructuring charge of $2.2 million in connection with one-time employee termination costs, including severance and other benefits, all of which have been paid as of December 31, 2019. The Company’s ability to continue its operations is dependent upon its ability to obtain additional capital in the future and achieve profitable operations. The Company expects to continue to rely on outside sources of financing to meet its capital needs and the Company may never achieve positive cash flow. These consolidated financial statements do not include any adjustments to the specific amounts and classifications of assets and liabilities, which might be necessary should Inovio be unable to continue as a going concern. Inovio’s consolidated financial statements as of and for the year ended December 31, 2019 have been prepared on a going concern basis, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business for the foreseeable future. The Company has evaluated subsequent events after the balance sheet date through the date it issued these financial statements. Consolidation These consolidated financial statements include the accounts of Inovio Pharmaceuticals, Inc. and its subsidiaries. The Company consolidates its wholly-owned subsidiaries Genetronics, Inc. and VGX Pharmaceuticals Inc. ("VGX"), and records a non-controlling interest for 39% of its subsidiary Geneos Therapeutics, Inc. ("Geneos") as well as 15% of VGX Animal Health, Inc., a subsidiary of VGX. All intercompany accounts and transactions have been eliminated upon consolidation. Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one segment operating primarily within the United States. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and short-term investments. The Company limits its exposure to credit loss by placing its cash and investments with high credit quality financial institutions. Additionally, the Company has established guidelines regarding diversification of its investments and their maturities which are designed to maintain principal and maximize liquidity. The Company has contracts with certain of its customers that have represented more than 10% of the Company's total revenues, as discussed in Note 7. Fair value of Financial Instruments The Company’s financial instruments consist principally of cash equivalents, short-term investments and investments in affiliated entities. The carrying amounts of cash equivalents approximate the related fair values due to the short-term maturities of these instruments. Investments are recorded at fair value, based on current market valuations. After the adoption of Accounting Standards Update ("ASU") No. 2016-01 on January 1, 2018, unrealized gains and losses on the Company's equity investment in its affiliated entity Plumbline Life Sciences, Inc. ("PLS") are reported in the consolidated statement of operations as a gain (loss) on investment in affiliated entities. The Company’s investment in GeneOne, an affiliated entity, is accounted for at fair value on a recurring basis, with changes in fair value recorded on the consolidated statements of operations within gain (loss) from investment in affiliated entity. The Company carries convertible notes and bonds at face value less unamortized debt discount and issuance costs on its consolidated balance sheet, and it presents the fair value of such convertible notes and bonds for disclosure purposes only. Cash and Cash Equivalents Cash equivalents are considered by the Company to be highly liquid investments purchased with original maturities of three months or less from the date of purchase. Cash and cash equivalents included certain money market accounts at December 31, 2019 and 2018 . Investments The Company defines investments as income-yielding securities that can be readily converted into cash or equity investments classified as available-for-sale. Investments included mutual funds and equity investments in the Company’s affiliated entities, PLS and GeneOne, at December 31, 2019 . Investments included mutual funds, United States corporate debt securities and an equity investment in the Company's affiliated entities, PLS and GeneOne, at December 31, 2018 . Accounts Receivable Accounts receivable are recorded at invoiced amounts and do not bear interest. The Company performs ongoing credit evaluations of its customers’ financial condition. Credit is extended to customers as deemed necessary and generally does not require collateral. Management believes that the risk of loss is significantly reduced due to the quality and financial position of the Company's customers. No allowance for doubtful accounts was deemed necessary at December 31, 2019 and 2018 . Fixed Assets Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful life of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the remaining term of the related leases or the estimated economic useful lives of the improvements. Repairs and maintenance are expensed as incurred. Long-Lived Assets All long-lived assets are reviewed for impairment in value when changes in circumstances dictate, based upon undiscounted future operating cash flows, and appropriate losses are recognized and reflected in current earnings, to the extent the carrying amount of an asset exceeds its estimated fair value determined by the use of appraisals, discounted cash flow analyses or comparable fair values of similar assets. The Company has not recognized any losses on long-lived assets through December 31, 2019 . Valuation of Intangible Assets and Goodwill Intangible assets are amortized over their estimated useful lives ranging from two to 18 years . Acquired intangible assets are continuously being developed for the future economic viability contemplated at the time of acquisition. The Company is concurrently conducting preclinical studies and clinical trials using the acquired intangibles and has entered into licensing agreements for the use of these acquired intangibles. Historically, the Company has recorded patents at cost and amortized these costs using the straight-line method over the expected useful lives of the patents or 17 years , whichever is less. Patent cost consists of the consideration paid for patents and related legal costs. Effective as of the acquisition of VGX in 2009, all new patent costs are expensed as incurred, with patent costs capitalized as of that date continuing to be amortized over the expected life of the patent. License costs are recorded based on the fair value of consideration paid and are amortized using the straight-line method over the shorter of the expected useful life of the underlying patents or the term of the related license agreement to the extent the license has an alternative future use. As of December 31, 2019 and 2018, the Company’s intangible assets resulting from the acquisition of VGX, as well as the acquisitions of two other companies, Inovio AS and Bioject Medical Technologies, Inc. ("Bioject"), and additional intangibles including previously capitalized patent costs and license costs, net of accumulated amortization, totaled $3.7 million and $4.8 million , respectively. The determination of the value of intangible assets requires management to make estimates and assumptions that affect the Company’s consolidated financial statements. The Company assesses potential impairments to intangible assets when there is evidence that events or changes in circumstances indicate that the carrying amount of an asset may not be recovered. The Company’s judgments regarding the existence of impairment indicators and future cash flows related to intangible assets are based on operational performance of its acquired businesses, market conditions and other factors. If impairment is indicated, the Company will reduce the carrying value of the intangible asset to fair value. While current and historical operating and cash flow losses are potential indicators of impairment, the Company believes the future cash flows to be received from its intangible assets will exceed the intangible assets’ carrying value, and accordingly, the Company has not recognized any impairment losses through December 31, 2019. Goodwill represents the excess of acquisition cost over the fair value of the net assets of acquired businesses. Goodwill is reviewed for impairment at least annually at November 30, or more frequently if an event occurs indicating the potential for impairment. During its goodwill impairment review, the Company may assess qualitative factors to determine whether it is more likely than not that the fair value of its reporting unit is less than its carrying amount, including goodwill. The qualitative factors include, but are not limited to, macroeconomic conditions, industry and market considerations, and the overall financial performance of the Company. If, after assessing the totality of these qualitative factors, the Company determines that it is not more likely than not that the fair value of its reporting unit is less than its carrying amount, then no additional assessment is deemed necessary. Otherwise, the Company proceeds to perform the two-step test for goodwill impairment. The first step involves comparing the estimated fair value of the reporting unit with its carrying value, including goodwill. If the carrying amount of the reporting unit exceeds its fair value, the Company performs the second step of the goodwill impairment test to determine the amount of loss, which involves comparing the implied fair value of the goodwill to the carrying value of the goodwill. The Company may also elect to bypass the qualitative assessment in a period and elect to proceed to perform the first step of the goodwill impairment test. The Company performed its annual assessment for goodwill impairment as of November 30, 2019, identifying no impairment. Although there are inherent uncertainties in this assessment process, the estimates and assumptions the Company is using are consistent with its internal planning. If these estimates or their related assumptions change in the future, the Company may be required to record an impairment charge on all or a portion of its goodwill and intangible assets. Furthermore, the Company cannot predict the occurrence of future impairment triggering events nor the impact such events might have on its reported asset values. Future events could cause the Company to conclude that impairment indicators exist and that goodwill or other intangible assets associated with its acquired businesses are impaired. Any resulting impairment loss could have an adverse impact on the Company’s results of operations. See Note 9 for further discussion of the Company’s goodwill and intangible assets. Income Taxes The Company recognizes deferred tax assets and liabilities for temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities along with net operating loss and tax credit carry forwards. The Company records a valuation allowance against its deferred tax assets to reduce the net carrying value to an amount that it believes is more likely than not to be realized. When the Company establishes or reduces the valuation allowance against its deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made. Valuation allowances against the Company’s deferred tax assets were $137.2 million and $115.0 million at December 31, 2019 and 2018 , respectively. Changes in the valuation allowances, when they are recognized in the provision for income taxes, are included as a component of the estimated annual effective tax rate. Collaboration Agreements The Company assesses whether its collaboration agreements are subject to Accounting Standards Codification ("ASC") 808: Collaborative Arrangements (“Topic 808”) based on whether they involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards. To the extent that the arrangement falls within the scope of Topic 808, the Company assesses whether the payments between the Company and the collaboration partner are subject to other accounting literature. If payments from the collaboration partner to the Company represent consideration from a customer, then the Company accounts for those payments within the scope of Topic 606. However, if the Company concludes that its collaboration partner is not a customer for certain activities, such as for certain collaborative research and development activities, the Company presents such payments as a reduction of research and development expense. Revenue Recognition Effective January 1, 2018, the Company adopted ASU 2014-09, Revenue from Contracts with Customers (“Topic 606”) using the modified retrospective method which consisted of applying and recognizing the cumulative effect of Topic 606 at the date of initial application. The Company recognizes revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies its performance obligations. At contract inception, the Company assesses the goods or services agreed upon within each contract and assess whether each good or service is distinct and determine those that are performance obligations. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements The Company enters into collaborative arrangements with partners that typically include payment of one or more of the following: (i) license fees; (ii) product supply services; (iii) milestone payments related to the achievement of developmental, regulatory, or commercial goals; and (iv) royalties on net sales of licensed products. Where a portion of non-refundable, upfront fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as deferred revenue and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, the Company must develop estimates and assumptions that require judgment of management to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation. The standalone selling price may include items such as forecasted revenues, development timelines, discount rates and probabilities of technical and regulatory success. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Product Supply Services Arrangements that include a promise for future supply of drug product for either clinical development or commercial supply at the licensee’s discretion are generally considered as options. The Company assesses if these options provide a material right to the licensee and if so, they are accounted for as separate performance obligations. The Company evaluates whether it is the principal or agent in the arrangement. The Company had determined that it is the principal in the current arrangements as the Company controls the product supply before it is transferred to the customer. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company's or its collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaborative arrangements. Grants The Company has determined that as of January 1, 2018, accounting for the Company’s various grant agreements falls under the contributions guidance under Subtopic 958-605, Not-for-Profit Entities-Revenue Recognition , which is outside the scope of Topic 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. Beginning on January 1, 2018, all contributions received from current grant agreements are recorded as a contra- expense as opposed to revenue on the consolidated statement of operations. Derivative Liabilities The Company evaluates its debt and equity issuances to determine if those contracts or embedded components of those contracts qualify as derivatives requiring separate recognition in the Company's financial statements. The result of this accounting treatment is that the fair value of the embedded derivative is revalued at each balance sheet date and recorded as a liability, and the change in fair value during the reporting period is recorded in other income (expense) in the consolidated statements of operations. In circumstances where the embedded conversion option in a convertible instrument is required to be bifurcated and there are also other embedded derivative instruments in the convertible instrument that are required to be bifurcated, the bifurcated derivative instruments are accounted for as a single, compound derivative instrument. The classification of derivative instruments, including whether such instruments should be recorded as liabilities or as equity, is reassessed at the end of each reporting period. Derivative instrument liabilities are classified in the balance sheet as current or non-current based on whether or not net-cash settlement of the derivative instrument is expected within twelve months of the balance sheet date. Foreign Currency Transactions The functional and presentation currency of the Company is the U.S. dollar. Transactions denominated in a currency other than the functional currency are recorded on the initial recognition at the exchange rate at the date of the transaction. After initial recognition, monetary assets and liabilities denominated in foreign currency are remeasured at the end of each reporting period into the functional currency at the exchange rate at that date. Exchange differences are included in general and administrative expenses in the consolidated statement of operations. Non-monetary assets and liabilities measured at cost are remeasured at the exchange rate at the date of the transaction. Research and Development Expenses The Company’s activities have largely consisted of research and development efforts related to developing electroporation delivery technologies and DNA immunotherapies and vaccines. Research and development expenses consist of expenses incurred in performing research and development activities including salaries and benefits, facilities and other overhead expenses, clinical trials, contract services and other outside expenses. Research and development expenses are charged to operations as they are incurred. These expenses result from the Company's independent research and development efforts as well as efforts associated with collaborations and licensing arrangements. The Company reviews and accrues clinical trial expense based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of studies and other events. The Company follows this method since reasonably dependable estimates of the costs applicable to various stages of a research agreement or clinical trial can be made. Accrued clinical trial costs are subject to revisions as trials progress. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. Historically, revisions have not resulted in material changes to research and development expense; however, a modification in the protocol of a clinical trial or cancellation of a trial could result in a charge to the Company's results of operations. Net Loss Per Share Basic net loss per share is computed by dividing the net loss for the year by the weighted average number of common shares outstanding during the year. Diluted net loss per share is calculated in accordance with the treasury stock method for the outstanding stock options, restricted stock units and warrants and reflects the potential dilution that would occur if securities or other contracts to issue common stock were exercised or converted to common stock. For the year ended December 31, 2019, the dilutive impact of the outstanding Notes and Bonds issued by the Company (discussed in Note 10) has been considered using the "if-converted" method. The calculation of diluted net loss per share requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the options or other securities and the presumed exercise of such securities are dilutive to net loss per share for the period, an adjustment to net loss used in the calculation is required to remove the change in fair value of such securities from the numerator for the period. Likewise, an adjustment to the denominator is required to reflect the related dilutive shares, if any. The following tables reconcile the components of the numerator and denominator included in the calculations of diluted net loss per share: Year Ended December 31, 2019 2018 2017 Numerator Net loss attributable to Inovio Pharmaceuticals, Inc. (numerator for use in basic net loss per share) $ (119,359,219 ) $ (96,967,830 ) $ (88,205,772 ) Adjustment for decrease in fair value of warrant liability — — (806,819 ) Numerator for use in diluted net loss per share $ (119,359,219 ) $ (96,967,830 ) $ (89,012,591 ) Denominator Weighted average number of common shares outstanding (denominator for use in basic net loss per share) 98,717,999 92,539,997 81,777,493 Effect of dilutive potential common shares — — 140,529 Denominator for use in diluted net loss per share 98,717,999 92,539,997 81,918,022 Net loss per share, diluted $ (1.21 ) $ (1.05 ) $ (1.09 ) Net loss per share, basic $ (1.21 ) $ (1.05 ) $ (1.08 ) The following table summarizes potential shares of common stock that were excluded from diluted net loss per share calculation because of their anti-dilutive effect: Year Ended December 31, 2019 2018 2017 Options to purchase common stock 9,265,390 8,752,677 7,694,870 Restricted stock units 2,069,936 1,688,017 1,234,168 Convertible preferred stock 8,456 8,456 8,456 Convertible notes 14,585,653 — — August 2019 Bonds 3,799,071 — — December 2019 Bonds 1,009,450 — — Total 30,737,956 10,449,150 8,937,494 Leases The Company adopted ASU 2016‑02, Leases (Topic 842) (“Topic 842”) on January 1, 2019. For long-term operating leases, the Company recognized an operating lease right-of-use asset and an operating lease liability on its consolidated balance sheets. The lease liability is determined as the present value of future lease payments using an estimated rate of interest that the Company would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. The right-of-use asset is based on the liability adjusted for any prepaid or deferred rent. The Company determined the lease term at the commencement date by considering whether renewal options and termination options are reasonably assured of exercise. Fixed rent expense for the Company's operating leases is recognized on a straight-line basis over the term of the lease and is included in operating expenses on the consolidated statements of operations. Variable lease payments including lease operating expenses are recorded as incurred. Prior period amounts continue to be reported in accordance with the historic accounting under the previous lease guidance, ASC 840, Leases (Topic 840). See “Recent Accounting Pronouncements - Recently Adopted” below, for more information about the impact of the adoption of Topic 842. Stock-Based Compensation The Company incurs stock-based compensation expense related to restricted stock units and stock options. The fair value of restricted stock is determined by the closing price of the Company's common stock reported on the Nasdaq Global Select Market on the date of grant. The Company estimates the fair value of stock options granted using the Black-Scholes option pricing model. The Black-Scholes option pricing model was developed for use in estimating the fair value of traded options, which have no vesting restrictions and are fully transferable. In addition, option valuation models require the input of subjective assumptions, including the expected stock price volatility and expected option life. The Company amortizes the fair value of the awards on a straight-line basis over the requisite vesting period of the awards. Expected volatility is based on historical volatility. The expected life of options granted is based on historical expected life. The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant. The dividend yield is based on the fact that no dividends have been paid historically and none are currently expected to be paid in the foreseeable future. The Company recognizes forfeitures as they occur. The weighted average assumptions used in the Black-Scholes model for option grants to employees and directors are presented below: Year Ended December 31, 2019 2018 2017 Risk-free interest rate 2.42% 2.73% 2.20% Expected volatility 70% 72% 73% Expected life in years 6 6 6 Dividend yield — — — The Company adopted ASU 2018-07 on January 1, 2019, which generally aligned the accounting for stock-based compensation for non-employees with that of employees. The fair value of the stock options granted to non-employees was estimated using

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition During the year ended December 31, 2019 , the Company recognized total revenue under collaborative research and development and other agreements determined to be contracts with a customer of $3.2 million from AstraZeneca and $917,000 from various other contracts. The Company defers revenue when a contract is entered into with a collaborator and cash payments are received prior to satisfaction of the related performance obligation. Of the total revenue recognized during the year ended December 31, 2019 , $293,000 was in deferred revenue as of December 31, 2018 . During the year ended December 31, 2018 , the Company recognized revenue of $1.3 million that was included in deferred revenue at December 31, 2017 . Performance obligations are generally satisfied within 12 months of the initial contract date.

Collaborative Agreements

Collaborative Agreements	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Agreements	Collaborative Agreements ApolloBio Corporation On December 29, 2017, the Company entered into an Amended and Restated License and Collaboration Agreement (the "ApolloBio Agreement"), with ApolloBio Corporation ("ApolloBio"), with an effective date of March 20, 2018. Under the terms of the ApolloBio Agreement, the Company granted to ApolloBio the exclusive right to develop and commercialize VGX-3100, its DNA immunotherapy product designed to treat pre-cancers caused by HPV, within the territories of China, Hong Kong, Macao, Taiwan, and may include Korea in the event that no patent covering VGX-3100 is issued in China within the three years following the effective date of the ApolloBio Agreement. Under the ApolloBio Agreement, the Company received proceeds of $19.4 million in March 2018, which comprised the upfront payment of $23.0 million less $2.2 million in foreign income taxes and $1.4 million in certain foreign non-income taxes. The foreign income taxes were recorded as a provision for income taxes and the foreign non-income taxes were recorded as a general and administrative expense, on the consolidated statement of operations during the quarter ended March 31, 2018. The Company also incurred advisory fees of $960,000 in connection with receiving the upfront payment from ApolloBio. These fees were determined to be incremental costs of obtaining the contract. The Company applied the practical expedient that permits a company to expense incremental costs to obtain a contract when the expected amortization period is one year or less and recorded the fees in general and administrative expense during the quarter ended March 31, 2018. No additional advisory fees are due related to the ApolloBio Agreement. In addition to the upfront payment, the Company is entitled to receive up to an aggregate of $20.0 million , less required income, withholding or other taxes, upon the achievement of specified milestones related to the regulatory approval of VGX-3100 in the United States, China and Korea. In the event that VGX-3100 is approved for marketing, the Company will be entitled to receive royalty payments based on a tiered percentage of annual net sales, with such percentage being in the low- to mid-teens, subject to reduction in the event of generic competition in a particular territory. ApolloBio’s obligation to pay royalties will continue for 10 years after the first commercial sale in a particular territory or, if later, until the expiration of the last-to-expire patent covering the licensed products in the specified territory. The Company evaluated the terms of the ApolloBio Agreement under Topic 606, and the license to VGX-3100 in the territories was identified as the only distinct performance obligation on a standalone basis as of the inception of the agreement. The Company concluded that the license was distinct from potential future manufacturing and supply obligations. The Company further determined that the transaction price under the agreement consisted of the $23.0 million upfront payment. The future potential milestone amounts were not included in the transaction price, as they were all determined to be fully constrained. As part of the evaluation of the development and regulatory milestones constraint, the Company determined that the achievement of such milestones is contingent upon success in future clinical trials and regulatory approvals, each of which is uncertain at this time. Future potential milestone amounts may be recognized as revenue under the ApolloBio Agreement, as well as under other collaborative research and development arrangements, if unconstrained. Reimbursable program costs will be recognized proportionately with the performance of the underlying services or delivery of drug supply and are excluded from the transaction price. The ApolloBio Agreement will continue in force until ApolloBio has no remaining royalty obligations. Either party may terminate the ApolloBio Agreement in the event the other party shall materially breach or default in the performance of its material obligations thereunder and such default continues for a specified period after written notice thereof. In addition, ApolloBio may terminate the ApolloBio Agreement at any time beginning one year after the effective date for any reason upon 90 days written notice to the Company. Under Topic 606, the entire transaction price of $23.0 million was allocated to the license performance obligation. The Company determined that during the quarter ended June 30, 2018, the transfer of technology occurred and accordingly, the performance obligation was fully satisfied. The Company has recorded the gross upfront payment received from ApolloBio of $23.0 million as revenue under collaborative research and development arrangements on the consolidated statement of operations during the year ended December 31, 2018. AstraZeneca On August 7, 2015, the Company entered into a license and collaboration agreement with MedImmune, the global biologics research and development arm of AstraZeneca ("AstraZeneca"). Under the agreement, AstraZeneca acquired exclusive rights to the Company's INO-3112 immunotherapy, renamed as MEDI0457, which targets cancers caused by human papillomavirus (HPV) types 16 and 18, with the ability to sublicense those license rights. AstraZeneca made an upfront payment of $27.5 million to the Company in September 2015. AstraZeneca may be obligated to make potential future development and regulatory event-based payments to the Company totaling up to $125 million and potential future commercial event-based payments totaling up to $115 million , in each case upon the achievement of specified milestones related to MEDI0457 set forth in the license and collaboration agreement. AstraZeneca will fund all development costs associated with MEDI0457 immunotherapy. The Company is entitled to receive up to mid-single to double-digit tiered royalties on MEDI0457 product sales. Under the agreement, AstraZeneca can also request the Company to provide certain clinical manufacturing at an agreed upon price. The Company determined these options did not represent material rights at the inception of the agreement. Within the broader collaboration, AstraZeneca had rights to co-develop up to two additional DNA-based cancer vaccine product candidates not included in the Company's current product pipeline. The Company has received notice that AstraZeneca intends to discontinue activities with respect to the research collaboration programs, other than MEDI0457, that were covered by the collaboration agreement. As of December 31, 2017, the Company had recognized all of the $27.5 million upfront payment as revenue, as all identified material performance obligations had been met with respect to that payment. In both December 2018 and March 2019, the Company recognized as revenue $2.0 million in milestone payments from AstraZeneca triggered by AstraZeneca’s initiation of the Phase 2 portion of ongoing clinical trials in the second and third major indication, respectively, under the agreement. During the year ended December 31, 2019 , the Company recognized total revenues of $3.2 million from AstraZeneca primarily for manufacturing services, for which the Company determined it was the principal in the arrangement as it controlled the product supply before it is transferred to the customer, and the milestone achieved as discussed above. As of December 31, 2019 and 2018 , the Company had an accounts receivable balance of $161,000 and $3.2 million , respectively, related to the collaboration agreement with AstraZeneca. Coalition for Epidemic Preparedness Innovations On April 11, 2018, the Company entered into agreements with CEPI, pursuant to which the Company intends to develop vaccine candidates against Lassa fever and MERS. The goal of the collaboration between the Company and CEPI is to conduct research and development so that investigational stockpiles will be ready for clinical efficacy trial testing during potential disease outbreaks. The agreements with CEPI contemplate preclinical studies, as well as Phase 1 and Phase 2 clinical trials, occurring over multiple years. As part of the arrangement between the parties, CEPI has agreed to fund up to an aggregate of $56 million of costs over a five -year period for preclinical studies, as well as planned Phase 1 and Phase 2 clinical trials, to be conducted by the Company and collaborators, with funding from CEPI based on the achievement of identified milestones. During the years ended December 31, 2019 and 2018 , the Company received funding of $6.3 million and $4.3 million , respectively, related to the CEPI grant and recorded those payments as contra-research and development expense. As of December 31, 2019 , the Company had a grant funding liability balance related to the CEPI grant of $5.0 million recorded as grant funding liability on the consolidated balance sheet related to the CEPI grant.

Short-term Investments

Short-term Investments	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Short-term Investments	Short-term Investments Short-term investments at December 31, 2019 consisted of mutual funds. Short-term investments at December 31, 2018 consisted of mutual funds and United States corporate debt securities. Short-term investments are recorded at fair value, based on current market valuations. Unrealized gains and losses on the Company's debt securities are excluded from earnings and reported as a separate component of other comprehensive loss until realized. Realized gains and losses are included in non-operating other income (expense) on the consolidated statements of operations and are derived using the specific identification method for determining the cost of the securities sold. During the years ended December 31, 2019 and 2018 , gross realized gain on investments of $594,000 and $20,000 , respectively, and gross realized loss on investments of $118,000 and $1.3 million , respectively, was recorded. No material balances were reclassified out of accumulated other comprehensive income (loss) for the years ended December 31, 2019, 2018 and 2017. Interest and dividends on investments classified as available-for-sale are included in interest income in the consolidated statements of operations. As of December 31, 2019 , the Company had 4 available-for-sale securities in a gross unrealized loss position, of which 2 with an aggregate total unrealized loss of $11,000 were in such position for longer than 12 months. The following is a summary of available-for-sale securities as of December 31, 2019 and 2018 : As of December 31, 2019 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 66,599,219 $ 754,709 $ (15,911 ) $ 67,338,017 As of December 31, 2018 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 57,842,955 $ — $ (528,084 ) $ 57,314,871 US corporate debt securities Less than 2 224,633 — (652 ) 223,981 Total investments $ 58,067,588 $ — $ (528,736 ) $ 57,538,852

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The guidance regarding fair value measurements establishes a three-tier fair value hierarchy which prioritizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets that are accessible at the measurement date; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. Assets and liabilities are classified based on the lowest level of input that is significant to the fair value measurements. The Company reviews the fair value hierarchy classification on a quarterly basis. Changes in the ability to observe valuation inputs may result in a reclassification of levels for certain securities within the fair value hierarchy. The Company did not have any transfer of assets and liabilities between Level 1, Level 2 and Level 3 of the fair value hierarchy during the years ended December 31, 2019 and 2018 . The following table presents the Company’s assets and liabilities that are measured at fair value on a recurring basis, and are determined using the following inputs as of December 31, 2019 : Fair Value Measurements at December 31, 2019 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 2,349,729 $ 2,349,729 $ — $ — Mutual funds 67,338,017 — 67,338,017 — Investments in affiliated entities 6,315,356 6,315,356 — — Total assets $ 76,003,102 $ 8,665,085 $ 67,338,017 $ — Liabilities: Derivative liability (Note 10) $ 8,819,023 $ — $ — $ 8,819,023 Total liabilities $ 8,819,023 $ — $ — $ 8,819,023 The following table presents the Company’s assets that are measured at fair value on a recurring basis, and are determined using the following inputs as of December 31, 2018 : Fair Value Measurements at December 31, 2018 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 9,646,507 $ 9,646,507 $ — $ — Mutual funds 57,314,871 — 57,314,871 — US corporate debt securities 223,981 — 223,981 — Investments in affiliated entities 9,405,913 9,405,913 — — Total assets $ 76,591,272 $ 19,052,420 $ 57,538,852 $ — Level 1 assets at December 31, 2019 and 2018 consisted of money market funds held by the Company that are valued at quoted market prices, as well as the Company’s investments in its affiliates, GeneOne and PLS. The Company accounts for its investment in 1,644,155 common shares of GeneOne based on the closing price of the shares on the Korean Stock Exchange on the applicable balance sheet date. The Company accounts for its investment in 395,758 common shares of PLS as an equity investment with a fair value based on the closing price of the shares on the Korea New Exchange (KONEX) Market on the applicable balance sheet date. Unrealized gains and losses on the Company's equity securities are reported in the consolidated statement of operations as a gain (loss) on investment in affiliated entities. Level 2 assets at December 31, 2019 consisted of mutual funds. Level 2 assets at December 31, 2018 consisted of U.S. corporate debt securities and mutual funds. Level 2 assets held by the Company that are initially valued at the transaction price and subsequently valued, at the end of each reporting period, typically utilizing market observable data. The Company obtains the fair value of its Level 2 assets from a professional pricing service, which may use quoted market prices for identical or comparable instruments, or inputs other than quoted prices that are observable either directly or indirectly. The professional pricing service gathers quoted market prices and observable inputs from a variety of industry data providers. The valuation techniques used to measure the fair value of the Company's Level 2 financial instruments were derived from non-binding market consensus prices that are corroborated by observable market data, quoted market prices for similar instruments, or pricing models such as discounted cash flow techniques. The Company validates the quoted market prices provided by the primary pricing service by comparing the service's assessment of the fair values of the Company's investment portfolio balance against the fair values of the Company's investment portfolio balance obtained from an independent source. In March 2019, August 2019 and December 2019, the Company issued the Convertible Notes, August 2019 Bonds and December 2019 Bonds, respectively. The carrying value of the Notes and Bonds approximates the fair value as December 31, 2019. See Note 10 for additional information. There were no Level 3 assets held as of December 31, 2019 and 2018 . Level 3 liabilities held at December 31, 2019 consisted of the embedded conversion option contained in the August 2019 Bonds that met the criteria to be bifurcated and accounted for separately from the August 2019 Bonds (the "derivative liability") (see Note 10 below for more information). The derivative liability was recorded at fair value of $7.1 million upon the issuance of the August 2019 Bonds, and is subsequently remeasured to fair value at each reporting period. The derivative liability was initially valued and remeasured using a "with-and-without" method. The "with-and-without" methodology involves valuing the whole instrument on an as-is basis and then valuing the instrument without the embedded conversion option. The difference between the entire instrument with the embedded conversion option compared to the instrument without the embedded conversion option is the fair value of the derivative, recorded as the derivative liability. There was no derivative liability associated with the issuance of the December 2019 Bonds. The fair value of the August 2019 Bonds with the conversion option is estimated using a Monte Carlo simulation approach. The key inputs to valuing the August 2019 Bonds with the conversion option on the date of issuance and as of December 31, 2019 include the Company’s stock price on the valuation date; the expected annual volatility of the Company’s common stock, and the discount yield, which was derived by making the fair value of the August 2019 Bonds equal to the face value on the issuance date. Fair value measurements are highly sensitive to changes in these inputs and significant changes in these inputs could result in a significantly higher or lower fair value. The following table presents the changes in fair value of the derivative liability for the year ended December 31, 2019 : Balance at December 31, 2018 $ — Initial fair value upon issuance of the August 2019 Bonds 7,055,371 Change in fair value 1,763,652 Balance at December 31, 2019 $ 8,819,023 There were no Level 3 liabilities held as of December 31, 2018 .

Major Customers and Concentrati

Major Customers and Concentration of Credit Risk	12 Months Ended
	Dec. 31, 2019
Risks and Uncertainties [Abstract]
Major Customers and Concentration of Credit Risk	Major Customers and Concentration of Credit Risk Customer 2019 Revenue % of Total Revenue 2018 Revenue % of Total Revenue 2017 Revenue % of Total Revenue ApolloBio $ — — % $ 23,000,000 75 % $ — — % AstraZeneca 3,194,877 78 6,850,424 23 22,269,773 53 DARPA — — — — 9,983,927 24 Roche — — — — 6,107,254 14 All other, including affiliated entities 917,053 22 631,473 2 3,859,132 9 Total revenue $ 4,111,930 100 % $ 30,481,897 100 % $ 42,220,086 100 % During the years ended December 31, 2019 and 2018 , the Company recognized revenue from various license fees and collaborative research and development agreements. The Company has determined that as of January 1, 2018, accounting for the Company’s various grant agreements falls under the contributions guidance under Subtopic 958-605 , Not-for-Profit Entities-Revenue Recognition , which is outside the scope of Topic 606. Beginning on January 1, 2018, all contributions received from current grant agreements have been recorded as a contra-expense as opposed to revenue on the consolidated statements of operations, as discussed in Note 2. During the year ended December 31, 2017 , the Company recognized revenue from various license fees, collaborative research and development agreements, grants and government contracts. As of December 31, 2019 , $469,000 , or 67% , and $161,000 , or 23% , of the Company's accounts receivable was attributable to MCDC and AstraZeneca, respectively. As of December 31, 2018 , $ 3.2 million , or 98% , of the Company's accounts receivable was attributable to AstraZeneca. There is minimal credit risk with these customers based upon collection history, their size and financial condition. Accordingly, the Company does not consider it necessary to record a reserve for uncollectible accounts receivable.

Fixed Assets

Fixed Assets	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Fixed Assets	Fixed Assets Fixed assets at December 31, 2019 and 2018 consist of the following: Cost Accumulated Depreciation and Amortization Net Book Value As of December 31, 2019 Leasehold improvements $ 15,007,935 $ (4,996,777 ) $ 10,011,158 Laboratory equipment 4,102,467 (3,229,357 ) 873,110 Office furniture and fixtures 3,048,053 (1,944,293 ) 1,103,760 Computer equipment and other 3,781,020 (2,996,031 ) 784,989 $ 25,939,475 $ (13,166,458 ) $ 12,773,017 As of December 31, 2018 Leasehold improvements $ 14,909,341 $ (3,464,444 ) $ 11,444,897 Laboratory equipment 4,031,965 (2,425,854 ) 1,606,111 Office furniture and fixtures 3,198,803 (1,767,653 ) 1,431,150 Computer equipment and other 3,808,824 (2,341,968 ) 1,466,856 $ 25,948,933 $ (9,999,919 ) $ 15,949,014 Depreciation expense for the years ended December 31, 2019 , 2018 and 2017 was $3.6 million , $3.7 million and $1.9 million , respectively. The Company determined that the carrying value of these long-lived assets was not impaired during the periods presented. During the year ended December 31, 2019 the Company disposed of fixed assets with a net book value of $6,000 and accumulated depreciation of $432,000 .

Goodwill and Intangible Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets The following sets forth goodwill and intangible assets by major asset class: December 31, 2019 December 31, 2018 Weighted Average Useful Life (Yrs) Gross Accumulated Amortization Net Book Value Gross Accumulated Amortization Net Book Value Indefinite lived: Goodwill(a) $ 10,513,371 $ — $ 10,513,371 $ 10,513,371 $ — $ 10,513,371 Definite lived: Patents 10 5,802,528 (5,802,528 ) — 5,802,528 (5,742,079 ) 60,449 Licenses 10 1,323,761 (1,248,104 ) 75,657 1,323,761 (1,219,357 ) 104,404 CELLECTRA ® (b) 8 8,106,270 (8,106,270 ) — 8,106,270 (7,679,190 ) 427,080 GHRH(b) 11 335,314 (335,314 ) — 335,314 (303,630 ) 31,684 Bioject (c) 12 5,100,000 (2,175,556 ) 2,924,444 5,100,000 (1,882,222 ) 3,217,778 Other(d) 18 4,050,000 (3,356,250 ) 693,750 4,050,000 (3,131,250 ) 918,750 Total intangible assets 11 24,717,873 (21,024,022 ) 3,693,851 24,717,873 (19,957,728 ) 4,760,145 Total goodwill and intangible assets $ 35,231,244 $ (21,024,022 ) $ 14,207,222 $ 35,231,244 $ (19,957,728 ) $ 15,273,516 (a) Goodwill was recorded from the Inovio AS acquisition in January 2005, the acquisition of VGX in June 2009 and the acquisition of Bioject in April 2016 for $3.9 million , $6.2 million and $400,000 , respectively. (b) CELLECTRA ® and GHRH are developed technologies which were recorded from the acquisition of VGX. (c) Bioject intangible assets represent the estimated fair value of developed technology and intellectual property which were recorded from the Bioject asset acquisition. (d) Other intangible assets represent the estimated fair value of acquired intellectual property from the Inovio AS acquisition. Aggregate amortization expense on intangible assets was $1.1 million , $1.2 million and $1.6 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. Amortization expense related to intangible assets at December 31, 2019 is expected to be incurred as follows: Year ending December 31, 2020 $ 547,081 2021 520,414 2022 492,818 2023 275,760 2024 253,333 Thereafter 1,604,445 $ 3,693,851 There were no impairment or impairment indicators present and no losses were recorded during the years ended December 31, 2019 , 2018 and 2017 , respectively.

Convertible Debt (Notes)

Convertible Debt (Notes)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Convertible Debt	Convertible Debt Convertible Senior Notes On February 19, 2019 and March 1, 2019, the Company completed a private placement of $78.5 million aggregate principal amount of its 6.50% convertible senior notes due 2024 (the “Notes”). The Notes were sold in a private offering to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended. Net proceeds from the offering were approximately $75.7 million . The Notes are senior unsecured obligations of the Company and accrue interest payable in cash semi-annually in arrears on March 1 and September 1 of each year, beginning on September 1, 2019, at a rate of 6.50% per annum. The Notes will mature on March 1, 2024, unless earlier converted, redeemed or repurchased. Prior to the close of business on the business day immediately preceding November 1, 2023, the Notes will be convertible at the option of the holders only upon the satisfaction of certain circumstances. Thereafter, the Notes will be convertible at the option of the holders at any time until the close of business on the scheduled trading day immediately before the maturity date. Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of its common stock or a combination of cash and shares of its common stock, at its election. The initial conversion rate will be 185.8045 shares per $1,000 principal amount of Notes (equivalent to an initial conversion price of approximately $5.38 per share), subject to adjustment upon the occurrence of specified events. The Company may not redeem the Notes prior to March 1, 2022. On or after March 1, 2022, the Company may redeem all, or any portion, of the Notes for cash if the last reported sale price per share of the Company's common stock exceeds 130% of the conversion price on (i) each of at least 20 trading days (whether or not consecutive) during the 30 consecutive trading days ending on, and including, the trading day immediately before the Company sends the related redemption notice; and (ii) the trading day immediately before the date the Company sends such redemption notice. The redemption price will be equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest to, but excluding, the redemption date. The Company evaluated the accounting for the issuance of the Notes and concluded that the embedded conversion features meet the requirements for a derivative scope exception for instruments that are both indexed to an entity’s own stock and classified in stockholders’ equity in its consolidated balance sheet, and that the cash conversion guidance applies. Therefore, the Notes issuance proceeds of $78.5 million are allocated first to the liability component based on the fair value of non-convertible debt with otherwise identical residual terms with the residual proceeds allocated to equity for the conversion features. The Company determined that the fair value of the non-convertible debt upon issuance of the Notes was $62.2 million and recorded this amount as a liability and the offsetting amount as a debt discount as a reduction to the carrying value of the Notes on the closing date. The debt issuance costs associated with the Notes of $2.8 million are allocated to the liability and equity component in the same proportion as the issuance proceeds. The Company determined that all other features of the Notes were clearly and closely associated with a debt host and did not require bifurcation as a derivative liability, or the fair value of the feature was immaterial to the Company's consolidated financial statements. The balance of the Notes at December 31, 2019 is as follows: Principal amount $ 78,500,000 Unamortized debt discount on the liability component (14,082,302 ) Unamortized debt issuance cost (1,938,206 ) Accrued interest 1,700,833 Net carrying amount $ 64,180,325 The Company determined that the expected life of the Notes was equal to the period through November 1, 2023 as this represents the point at which the Notes are initially subject to repurchase by the Company at the option of the holders. Accordingly, the total debt discount of $18.6 million , inclusive of the fair value of the embedded conversion feature derivative at issuance, is being amortized using the effective interest method through November 1, 2023. The effective interest rate of the liability component is 13.1% . For the year ended December 31, 2019 , the Company recognized $7.0 million of interest expense related to the Notes, of which $4.4 million related to the contractual interest coupon. As of December 31, 2019 , there have not been any conversions or redemptions of the Notes. August 2019 Convertible Bonds On August 1, 2019, the Company closed a private placement of the August 2019 Bonds with an aggregate principal amount of 18 billion Korean Won (KRW) (approximately USD $15.0 million based on the exchange rate on the date of issuance) issued to institutional investors led by Korea Investment Partners (KIP), a global venture capital and private equity firm based in Seoul, Korea. Net proceeds from the offering were approximately $14.5 million . The Company also announced its intent to pursue a listing of its securities on the KOSDAQ Market of the Korea Exchange (KOSDAQ) in the form of Korean Depositary Receipts (KDRs) representing shares of common stock. The August 2019 Bonds, which are unsecured obligations of the Company, were issued on August 1, 2019 and will accrue interest at a coupon rate of 1.00% per annum, payable quarterly. The August 2019 Bonds will mature on July 31, 2024, unless earlier converted or repurchased. The outstanding August 2019 Bonds will be repaid at maturity at a price equal to the principal of the outstanding bonds to be repaid plus a premium on such bonds to provide an internal rate of return with respect to such bonds of 6.00% . Commencing on August 1, 2020, the August 2019 Bonds will be convertible until the date that is one month prior to maturity date. Upon conversion, the Company will deliver KDRs, if the Company has any such securities listed on the KOSDAQ at that time, or otherwise shares of common stock, if KDRs are not listed on KOSDAQ at that time or the converting holder requests delivery of shares of common stock. The initial conversion rate is 211.0595 shares per KRW 1,000,000 in principal amount (equivalent to an initial conversion price of approximately USD $4.00 per share based on the exchange rate as of July 30, 2019), subject to adjustment upon the occurrence of specified events. The conversion rate is subject to reset on January 2, 2020 and on each three month anniversary thereafter until the maturity date to the then current market price if the current market price is lower than the conversion price then in effect; provided that the conversion rate will not exceed 351.7658 shares per KRW 1,000,000 (equivalent to a conversion price of approximately USD $2.40 per share based on the exchange rates as of July 30, 2019). The August 2019 Bonds will be subject to repurchase by the Company at the option of the bondholders from and including July 31, 2022 up to the date that is one month prior to the maturity date at a repurchase price equal to the principal of the August 2019 Bonds to be repurchased plus a premium in order to provide an internal rate of return with respect to the August 2019 Bonds of 6.00% . In addition, upon the occurrence of a fundamental change (as defined in the August 2019 Bonds), the Company will be required to offer to repurchase the August 2019 Bonds at a repurchase price equal to the principal amount thereof plus accrued and unpaid interest thereon but excluding the applicable repurchase date. Upon the occurrence of an event of default (as defined in the August 2019 Bonds), with the approval of at least 25% of the bondholders, the Company will be required to offer to repurchase the August 2019 Bonds at a repurchase price equal to the principal amount thereof plus a premium in order to provide an internal rate of return with respect to the August 2019 Bonds of 8.00% . The Company evaluated the accounting for the issuance of the August 2019 Bonds and concluded that the embedded conversion feature is considered a derivative requiring bifurcation from the August 2019 Bonds as it does not meet the equity scope exception due to the fact that it is denominated in a currency other than the Company's functional currency. The fair value of the conversion feature at August 1, 2019 was $7.1 million , which was recorded as a reduction to the carrying value of the debt. This debt discount is being amortized to interest expense over the term of the debt using the effective interest method. The conversion option is accounted for as a derivative liability, which is revalued each reporting period with the resulting change in fair value reflected in other income (expense), net, in the consolidated statements of operations. The Company determined that all other features of the August 2019 Bonds were clearly and closely associated with a debt host and did not require bifurcation as a derivative liability, or the fair value of the feature was immaterial to the Company's consolidated financial statements. The balance of the August 2019 Bonds at December 31, 2019 is as follows: Principal amount $ 15,578,211 Unamortized debt discount (6,764,346 ) Unamortized debt issuance cost (255,185 ) Accretion of premium associated with the August 2019 Bonds 227,322 Accrued interest 38,946 Net carrying amount $ 8,824,948 The Company determined that the expected life of the August 2019 Bonds was equal to the period through August 1, 2022 as this represents the point at which the August 2019 Bonds are initially subject to repurchase by the Company at the option of the holders. Accordingly, the total debt discount of $7.3 million , inclusive of the fair value of the embedded conversion feature derivative at issuance, is being amortized using the effective interest method through August 1, 2022. The effective interest rate of the August 2019 Bonds is 29.4% . For the year ended December 31, 2019 , the Company recognized $982,000 of interest expense related to the August 2019 Bonds, of which $65,000 related to the contractual interest coupon. As of December 31, 2019 , there have not been any conversions or redemptions of the August 2019 Bonds. The derivative liability is valued at $8.8 million as of December 31, 2019 . The change in fair value of the derivative liability was $1.8 million for the year ended December 31, 2019 . December 2019 Convertible Bonds On December 26, 2019, the Company closed a private placement of convertible promissory notes (the “December 2019 Bonds”) with an aggregate principal amount of 4.7 billion KRW (approximately USD $4.1 million based on the exchange rate on the date of issuance) issued to a Korea-based institutional investor. Net proceeds from the offering were approximately $4.0 million . The December 2019 Bonds, which are unsecured obligations of the Company, were issued on December 31, 2019 and will accrue interest at a coupon rate of 1.00% per annum, payable quarterly. The December 2019 Bonds will mature on December 31, 2024, unless earlier converted or repurchased. The outstanding December 2019 Bonds will be repaid at maturity at a price equal to the principal of the outstanding bonds to be repaid plus a premium on such bonds to provide an internal rate of return with respect to such bonds of 6.00% . Commencing on December 31, 2020, the December 2019 Bonds will be convertible until the date that is one month prior to maturity date. Upon conversion, the Company will deliver KDRs, if the Company has any such securities listed on the KOSDAQ at that time, or otherwise shares of common stock of the Company. The initial conversion rate will be 214.7766 shares per KRW 1,000,000 principal amount of Bonds (equivalent to an initial conversion price of approximately USD $4.00 per share based on the exchange rate as of December 19, 2019), subject to adjustment upon the occurrence of certain events. The conversion rate is subject to reset on July 2, 2020 and on each three month anniversary thereafter until the maturity date to the then current market price if the current market price is lower than the conversion price then in effect; provided that the conversion rate will not exceed 357.961 1 shares per KRW1,000,000 (equivalent to a conversion price of approximately USD $2.40 per share based on the exchange rate as of December 19, 2019). The December 2019 Bonds will be subject to repurchase by the Company at the option of the bondholders from and including December 31, 2022 up to the date that is one month prior to the maturity date at a repurchase price equal to the principal of the December 2019 Bonds to be repurchased plus a premium on the Bonds in order to ensure an internal rate of return with respect to the Bonds equal to 6.00% . In addition, upon the occurrence of a fundamental change (as defined in the Subscription Agreement) the Company will be required to offer to repurchase the Bonds at a repurchase price equal to the principal amount thereof plus accrued and unpaid interest thereon to but excluding the applicable repurchase date. If certain bankruptcy and insolvency-related events of default occur, the principal of, and accrued and unpaid interest on, all of the then outstanding December 2019 Bonds shall automatically become due and payable. If any other event of default occurs and is continuing, the holders of at least 25% of the in aggregate principal amount of the December 2019 Bonds by notice to the Company may declare the principal of, and accrued and unpaid interest on, all of the then-outstanding December 2019 Bonds to be due and payable. The Company evaluated the accounting for the issuance of the December 2019 Bonds and concluded that the embedded conversion feature does not require bifurcation from the December 2019 Bonds. Although the embedded conversion feature meets the definition of a derivative, it qualifies for the equity scope exception for instruments that are both indexed to an entity’s own stock and classified in stockholders’ equity in its consolidated balance sheet. The December 2019 Bonds are denominated in a foreign currency other than the Company’s functional currency, which would typically violate the settlement provision criteria when analyzing whether the conversion option is indexed to an entity’s own stock. However, per the terms of the agreement, the functional currency rate required to be used in a conversion scenario is fixed as of the date preceding the date of issuance of the Bonds. Therefore, the fluctuation in functional currency doesn’t impact the settlement of the conversion option. Further, as there is no cash conversion feature or beneficial conversion feature on the date of issuance, and the Bonds were not issued at a substantial premium, all of the proceeds were recorded as a liability. The Company determined that all other features of the December 2019 Bonds were clearly and closely associated with a debt host and did not require bifurcation as a derivative liability, or the fair value of the feature was immaterial to the Company's consolidated financial statements. The balance of the December 2019 Bonds at December 31, 2019 is as follows: Principal amount $ 4,067,644 Unamortized debt issuance cost (50,000 ) Accretion of premium associated with the December 2019 Bonds — Accrued interest — Net carrying amount $ 4,017,644 The Company determined that the expected life of the December 2019 Bonds was equal to the period through December 31, 2022 as this represents the point at which the December 2019 Bonds are initially subject to repurchase by the Company at the option of the holders. The effective interest rate of the December 2019 Bonds is 6.2% . For the year ended December 31, 2019, the Company recognized no interest expense related to the December 2019 Bonds. As of December 31, 2019, there have not been any conversions or redemptions of the December 2019 Bonds. As of December 31, 2019 , future minimum payments due under the Company's convertible debt instruments are as follows: Year ending December 31, Convertible Notes (1) August 2019 Bonds (2) December 2019 Bonds (2) Total 2020 $ 5,103,000 $ 156,000 $ 31,000 $ 5,290,000 2021 5,103,000 156,000 41,000 5,300,000 2022 5,103,000 156,000 41,000 5,300,000 2023 5,103,000 156,000 41,000 5,300,000 2024 81,051,000 20,021,000 5,236,000 106,308,000 Total $ 101,463,000 $ 20,645,000 $ 5,390,000 $ 127,498,000 (1) Amounts represent contractual amounts due under the Notes, including interest based on the fixed rate of 6.5% per year. (2) Amounts represent contractual amounts due under the August 2019 and December 2019 Bonds, including interest based on the fixed rate of 1% per year plus a premium on such bonds to provide an internal rate of return with respect to such Bonds of 6% at maturity.

Accounts Payable and Accrued Ex

Accounts Payable and Accrued Expenses	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Accounts Payable and Accrued Expenses	Accounts Payable and Accrued Expenses Accounts payable and accrued expenses at December 31, 2019 and 2018 consist of the following: As of December 31, 2019 2018 Trade accounts payable $ 6,919,081 $ 10,043,816 Accrued compensation 8,967,897 9,466,821 Accrued subcontract costs 273,508 83,812 Other accrued expenses 2,076,772 3,540,284 $ 18,237,258 $ 23,134,733

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred Stock Shares Outstanding as of December 31, Shares Authorized Shares Issued 2019 2018 Series C Preferred Stock, par $0.001 1,091 1,091 23 23 The shares of the Company’s Series C Preferred Stock have the following pertinent rights and privileges, as set forth in the Company’s Amended and Restated Certificate of Incorporation and its Certificates of Designations, Rights and Preferences related to the various series of preferred stock. Rights on Liquidation In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company (a “liquidation event”), before any distribution of assets of the Company shall be made to or set apart for the holders of common stock, the holders of Series C Preferred Stock, pari passu, are entitled to receive payment of such assets of the Company in an amount equal to $10,000 per share of such series of preferred stock, plus any accumulated and unpaid dividends thereon (whether or not earned or declared). If the assets of the Company available for distribution to stockholders exceed the aggregate amount of the liquidation preferences payable with respect to all shares of each series of preferred stock then outstanding, then, after the payment of such preferences is made or irrevocably set aside, the holders of the Company’s common stock are entitled to receive a pro rata portion of such assets based on the aggregate number of shares of common stock held by each such holder. The holders of the Company’s outstanding preferred stock shall participate in such a distribution on a pro-rata basis, computed based on the number of shares of common stock which would be held by such preferred holders if immediately prior to the liquidation event all of the outstanding shares of the preferred stock had been converted into shares of common stock at the then current conversion value applicable to each series. A Change of Control of the Company (as defined in the Certificates of Designations, Rights and Preferences) is not a liquidation event triggering the preferences described above, and is instead addressed by separate terms in the Series C Certificates of Designations, Rights, and Preferences. Although the liquidation preferences are in excess of the par value of $0.001 per share of the Company’s preferred stock, these preferences are equal to or less than the stated value of such shares based on their original purchase price. Voting Rights The holders of Series C Preferred Stock have full voting rights and powers equal to the voting rights and powers of holders of the Company’s common stock and are entitled to notice of any stockholders’ meeting in accordance with the Company’s Bylaws. Holders are entitled to vote on any matter upon which holders of the Company’s common stock have the right to vote, including, without limitation, the right to vote for the election of directors together with the holders of common stock as one class. Series C Preferred holders are entitled to 368 votes for each share of Series C Preferred Stock held. Holder Optional Conversion Right The holder of any share or shares of Series C Preferred Stock has the right at any time, at such holder’s option, to convert all or any lesser portion of such holder’s shares of the Preferred Stock into such number of fully paid and non-assessable shares of Common Stock as is determined by dividing (i) the aggregate Liquidation Preference applicable to the particular series of preferred shares, plus accrued and unpaid dividends thereon by (ii) the applicable Conversion Value (as defined in the relevant series’ Certificate of Designations, Rights and Preferences) then in effect for such series of preferred shares. As of December 31, 2019 , the Conversion Value was $27.20 , such that the outstanding shares of Series C Preferred Stock were convertible into 8,456 shares of common stock. The Company is not obligated to issue any fractional shares or scrip representing fractional shares upon such conversion and instead shall pay the holder an amount in cash equal to such fraction multiplied by the current market price per share of the Company’s common stock. Company Mandatory Conversion Option The Company has the option upon thirty (30) days prior written notice, to convert all of the outstanding shares of the Series C Preferred Stock into such number of fully paid and non-assessable shares of common stock as is determined by dividing (i) the aggregate Liquidation Preference of the shares of the relevant series of preferred stock to be converted, plus accrued and unpaid dividends thereon by (ii) the applicable Conversion Value (as defined in the relevant series’ Certificate of Designations, Rights and Preferences) then in effect, if the following triggering events have occurred: (i) the price of the Company’s common stock exceeds $72.00 per share for 20 out of 30 consecutive trading days; and (ii) the average daily trading volume (subject to adjustment for stock dividends, subdivisions and combinations) of the common stock exceeds 6,250 shares for at least 20 out of 30 consecutive trading days. Common Stock In May 2018, the Company entered into the Sales Agreement with Stifel, Nicolaus and Company (the “Placement Agent”) to sell shares of its common stock with aggregate gross proceeds of up to $100.0 million , from time to time, through an “at-the-market” equity offering program under which the Placement Agent will act as sales agent. Under the Sales Agreement, the Company will set the parameters for the sale of shares, including the number of shares to be issued, the time period during which sales are requested to be made, limitation on the number of shares that may be sold in any one trading day and any minimum price below which sales may not be made. The Sales Agreement provides that the Placement Agent will be entitled to compensation for its services in an amount equal to up to 3.0% of the gross proceeds from the sales of shares sold through the Placement Agent under the Sales Agreement. The Company has no obligation to sell any shares under the Sales Agreement, and may at any time suspend solicitation and offers under the Sales Agreement. During the year ended December 31, 2019 , the Company sold a total of 3,340,678 shares of common stock under the Sales Agreement. The sales were made at a weighted average price of $2.78 per share resulting in aggregate net proceeds of $9.1 million . As of December 31, 2019 , the Company may sell up to an additional $62.8 million in shares of its common stock under the Sales Agreement. The registration statement that registered with the SEC the shares that may be sold under the Sales Agreement expires on June 8, 2021. As described in Note 19 below, subsequent to December 31, 2019, the Company and the Placement Agent entered into a first and second amendment to the Sales Agreement to increase the amount of common stock that may be sold under the Sales Agreement from $100.0 million to $250.0 million . The Company also sold shares of common stock under the Sales Agreement subsequent to December 31, 2019. In June 2016, the Company entered into an At-the-Market Equity Offering Sales Agreement (the “Prior Sales Agreement”) with the same placement agent. The registration statement that registered with the SEC the shares sold under the Prior Sales Agreement expired on June 5, 2018, and no further sales can be made under the Prior Sales Agreement. The Company sold an aggregate of 3,911,104 shares of common stock under the Prior Sales Agreement resulting in aggregate net proceeds of $32.1 million . During the period from January 1, 2018 to June 5, 2018, the Company sold a total of 314,950 shares of common stock under the Prior Sales Agreement. The sales were made at a weighted average price of $5.07 per share resulting in aggregate net proceeds of $1.6 million . During the year ended December 31, 2017, the Company sold a total of 2,937,406 shares of common stock under the Prior Sales Agreement. The sales were made at a weighted average price of $8.41 per share resulting in aggregate net proceeds of $24.2 million . Warrants During the year ended December 31, 2018, warrants to purchase 284,091 shares of the Company's common stock were exercised, with net proceeds to the Company of $902,000 . As of December 31, 2019 and 2018, there were no common stock warrants outstanding. Stock Options and Restricted Stock Units The Company has a stock-based incentive plan, the 2016 Omnibus Incentive Plan (as amended to date, the "2016 Incentive Plan"), pursuant to which the Company may grant stock options, restricted stock awards, restricted stock units and other stock-based awards or short-term cash incentive awards to employees, directors and consultants. The 2016 Incentive Plan was originally approved by the Company's stockholders on May 13, 2016, and an amendment to the plan to increase the number of shares available for issuance was approved by the stockholders on May 8, 2019. The maximum number of shares of the Company’s common stock available for issuance over the term of the 2016 Incentive Plan may not exceed 16,000,000 shares, provided that commencing with the first business day of each calendar year beginning January 1, 2020, such maximum number of shares shall be increased by 2,000,000 shares of common stock unless the Board determines, prior to January 1 for any such calendar year, to increase such maximum amount by a fewer number of shares or not to increase the maximum amount at all for such year. On January 1, 2020, the maximum number of shares to be issued was increased by 2,000,000 . At December 31, 2019 , there were 16,000,000 shares of common stock reserved for issuance upon exercise of incentive awards granted and to be granted at future dates under the 2016 Incentive Plan. At December 31, 2019 , the Company had 8,214,032 shares of common stock available for future grant under the 2016 Incentive Plan, 2,069,936 shares underlying outstanding but unvested restricted stock units and options outstanding to purchase 4,497,736 shares of common stock under the 2016 Incentive Plan. The awards granted and available for future grant under the 2016 Incentive Plan generally vest over three years and have a maximum contractual term of ten years. The 2016 Incentive Plan terminates by its terms on March 9, 2026. The Amended and Restated 2007 Omnibus Incentive Plan (the "2007 Incentive Plan") was adopted on March 31, 2007 and terminated by its terms on March 31, 2017. At December 31, 2019 , the Company had options outstanding to purchase 4,767,654 shares of common stock under the 2007 Incentive Plan. The awards granted under the 2007 Incentive Plan generally vest over three years and have a maximum contractual term of ten years. Total employee and director stock-based compensation expense recognized in the consolidated statements of operations for the years ended December 31, 2019 , 2018 and 2017 was $9.8 million , $10.2 million and $12.9 million , respectively, of which $5.9 million , $5.9 million and $5.8 million was included in research and development expenses and $3.9 million , $4.3 million and $7.1 million was included in general and administrative expenses, respectively. At December 31, 2019 and 2018 , there was $3.4 million and $5.2 million , respectively, of total unrecognized compensation expense related to unvested stock options, which are each expected to be recognized over a weighted-average period of 1.7 years. At December 31, 2019 and 2018 , there was $4.3 million and $5.1 million , respectively, of total unrecognized compensation expense related to unvested restricted stock units, which is expected to be recognized over a weighted-average period of 1.6 years and 1.7 years, respectively. The Company adopted ASU 2018-07 on January 1, 2019, which generally aligned the accounting for stock-based compensation for non-employees with that of employees. The fair value of stock options granted to non-employees was estimated using the Black-Scholes pricing model. Total stock-based compensation expense for stock options and restricted stock units granted to non-employees for the years ended December 31, 2019 , 2018 and 2017 was $970,000 , $302,000 and $201,000 , respectively. As of December 31, 2019 , options to purchase 952,500 shares of common stock granted to non-employees remained outstanding. The following table summarizes total stock options outstanding at December 31, 2019 : Options Outstanding Options Exercisable Exercise Price Shares Underlying Options Outstanding Weighted-Average Remaining Contractual Life (in Years) Weighted Average Exercise Price Shares Underlying Options Exercisable Weighted Average Exercise Price $1.48-$3.00 903,257 3.4 $ 2.29 848,969 $ 2.26 $3.01-$6.00 4,066,998 7.9 $ 3.90 1,844,977 $ 4.12 $6.01-$9.00 3,454,212 6.1 $ 7.20 3,210,448 $ 7.24 $9.01-$12.00 220,880 5.8 $ 9.83 220,880 $ 9.83 $12.01-$15.00 620,043 4.2 $ 12.96 620,043 $ 12.96 9,265,390 6.5 $ 5.72 6,745,317 $ 6.37 At December 31, 2019 , the aggregate intrinsic value of options outstanding was $918,000 , the aggregate intrinsic value of options exercisable was $881,000 , and the weighted average remaining contractual term of options exercisable was 5.7 years. At December 31, 2019 , the aggregate intrinsic value of unvested restricted stock units was $6.8 million and the aggregate intrinsic value of restricted stock units which vested during the year ended December 31, 2019 was $3.5 million. At December 31, 2019 , options to purchase 9,265,390 shares of common stock and 2,069,936 restricted stock units were expected to vest. Stock option activity under the Company’s equity incentive plans during the year ended December 31, 2019 was as follows: Number of Shares Weighted-Average Exercise Price Balance, December 31, 2018 8,752,677 $ 6.35 Granted 2,596,468 3.39 Exercised (42,969 ) 2.62 Cancelled (2,040,786 ) 5.49 Balance, December 31, 2019 9,265,390 $ 5.72 Restricted stock unit activity under the Company’s equity incentive plans during the year ended December 31, 2019 was as follows: Number of Shares Balance, December 31, 2018 1,688,017 Granted 1,491,771 Vested (1,003,218 ) Cancelled (106,634 ) Balance, December 31, 2019 2,069,936 The weighted average exercise price per share was $6.27 for the 324,502 options which expired during the year ended December 31, 2019 , $5.17 for the 119,091 options which expired during the year ended December 31, 2018 and $9.67 for the 200,501 options which expired during the year ended December 31, 2017 . The weighted average grant date fair value per share was $2.19 , $2.86 and $4.33 for options granted during the years ended December 31, 2019 , 2018 and 2017 , respectively. The weighted average grant date fair value was $3.09 , $4.31 and $6.66 per share for restricted stock units granted during the years ended December 31, 2019 , 2018 and 2017 , respectively. The Company received $113,000 , $1.5 million and $2.3 million in proceeds from the exercise of stock options during the years ended December 31, 2019 , 2018 and 2017 , respectively. The aggregate intrinsic value of options exercised was $25,000 , $910,000 and $519,000 during the years ended December 31, 2019 , 2018 and 2017 , respectively.

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	Leases The Company leases approximately 82,200 square feet of office, laboratory, and manufacturing space in San Diego, California and 57,360 square feet of office space in Plymouth Meeting, Pennsylvania under various non-cancellable operating lease agreements with remaining lease terms of 3.9 to 9.9 years, which represent the non-cancellable periods of the leases. The Company has excluded the extension options from its lease terms in the calculation of future lease payments as they are not reasonably certain to be exercised. The Company's lease payments consist primarily of fixed rental payments for the right to use the underlying leased assets over the lease terms as well as payments for common area maintenance and administrative services. The Company has received customary incentives from its landlords, such as reimbursements for tenant improvements and rent abatement periods, which effectively reduce the total lease payments owed for these leases. The Company has evaluated all of its leases and determined that, effective upon the adoption of Topic 842, they were all operating leases. The Company performed an evaluation of its other contracts with customers and suppliers in accordance with Topic 842 and determined that, except for the real estate leases described above and various copier leases, none of its other contracts contain a right-of-use asset. Operating lease right-of-use assets and liabilities on the consolidated balance sheet represents the present value of the remaining lease payments over the remaining lease terms. Payments for additional monthly fees to cover the Company's share of certain facility expenses are not included in operating lease right-of-use assets and liabilities. The Company uses its incremental borrowing rate to calculate the present value of its lease payments, as the implicit rates in the leases are not readily determinable. As of December 31, 2019 , the maturities of the Company's operating lease liabilities were as follows: Year ending December 31, 2020 $ 3,891,000 2021 3,979,000 2022 4,052,000 2023 4,023,000 2024 3,001,000 Thereafter 12,951,000 Total remaining lease payments 31,897,000 Less: present value adjustment (9,412,236 ) Total operating lease liabilities 22,484,764 Less: current portion (2,074,842 ) Long-term operating lease liabilities $ 20,409,922 Weighted-average remaining lease term 8.2 years Weighted-average discount rate 8.4 % Lease costs included in operating expenses in the consolidated statements of operations for the years ended December 31, 2019 , 2018 and 2017 were $3.2 million , $3.4 million and $2.5 million , respectively. Operating lease costs consisting of the fixed lease payments included in operating lease liabilities are recorded on a straight-line basis over the lease terms. Variable lease costs are recorded as incurred. In the fourth quarter of 2019, the Company entered into two agreements to sublease a total of approximately 13,500 square feet in its Plymouth Meeting headquarters through periods between December 31, 2022 and March 31, 2025. As of December 31, 2018, prior to the adoption of Topic 842, annual future minimum lease payments under non-cancelable operating leases were as follows: Year ending December 31, 2019 $ 3,756,000 2020 3,891,000 2021 3,979,000 2022 4,052,000 2023 4,023,000 Thereafter 15,952,000 Total $ 35,653,000 In the normal course of business, the Company is a party to a variety of agreements pursuant to which it may be obligated to indemnify the other party. It is not possible to predict the maximum potential amount of future payments under these types of agreements due to the conditional nature of the Company's obligations and the unique facts and circumstances involved in each particular agreement. Historically, payments made by the Company under these types of agreements have not had a material effect on its business, consolidated results of operations or financial condition.

Investments in Affiliated Entit

Investments in Affiliated Entities	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Investments in Affiliated Entities	Investments in Affiliated Entities The Company held 1,644,155 common shares, representing a 7.5% and 7.8% ownership interest in GeneOne as of December 31, 2019 and 2018 , respectively, and 395,758 common shares, representing a 15.0% and 15.1% ownership interest in PLS as of December 31, 2019 and 2018 , respectively. Please see further information as discussed in Note 2 and Note 6.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes In accordance with the guidance pursuant to accounting for income taxes, a deferred tax asset or liability is determined based on the difference between the financial statement and tax basis of assets and liabilities as measured by the enacted tax rates which will be in effect when these differences reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax asset will be realized. The components of the provision for income taxes are presented in the following table: Year Ended December 31, 2019 2018 2017 Current: Federal $ 4,000 $ — $ — State 2,000 — — Foreign — 2,170,000 — 6,000 2,170,000 — Deferred: Federal (263,000 ) — State — — — Foreign — — — (263,000 ) — — $ (257,000 ) $ 2,170,000 $ — The reconciliation of income taxes attributable to continuing operations computed at the statutory tax rates to income tax expense (benefit), using a 21% statutory tax rate for December 31, 2019 and 2018 , and 35% statutory tax rate for December 31, 2017, is as follows: Year Ended December 31, 2019 2018 2017 Income (benefit) taxes at statutory rates $ (25,370,000 ) $ (19,908,000 ) $ (30,872,000 ) State income tax, net of federal benefit — (4,000 ) (4,000 ) Foreign income taxes — 2,170,000 — Change in valuation allowance 25,457,000 20,898,000 (20,965,000 ) Research and development tax credits (3,838,000 ) (3,170,000 ) (3,456,000 ) Change in fair value of warrants — (76,000 ) (282,000 ) Stock-based compensation 1,114,000 1,094,000 2,332,000 Uncertain tax positions 1,537,000 1,268,000 846,000 Expired NOLs and credits 616,000 2,176,000 454,000 Limited NOLs and credits (616,000 ) (2,176,000 ) (165,000 ) Change in tax rates 12,000 — 50,019,000 Other 831,000 (102,000 ) 2,093,000 $ (257,000 ) $ 2,170,000 $ — The income tax benefit recorded during the year ended December 31, 2019 of $0.3 million is principally due to a requirement under Accounting Standards Codification ("ASC") 740, Accounting for Income Taxes , that a company must consider all sources of income in order to determine the tax benefit resulting from a loss from continuing operations. As a result of the requirement under ASC 740-20-45-7, the pretax income which the Company generated from other comprehensive income was a source of income which resulted in the partial realization of the current year loss from continuing operations. Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2019 and 2018 are shown below: As of December 31, 2019 2018 Deferred tax assets: Capitalized research expense $ 6,300,000 $ 7,408,000 NOL carryforwards 110,788,000 89,399,000 Research and development and other tax credits 11,737,000 9,432,000 Deferred revenue 1,506,000 985,000 Deferred rent — 2,013,000 Stock-based compensation 3,255,000 3,408,000 Acquired intangibles 889,000 912,000 Derivative liability 1,852,000 — Interest expense 1,122,000 — Investment in affiliated entity 645,000 — Lease liability 4,722,000 — Other 2,413,000 2,693,000 145,229,000 116,250,000 Valuation allowance (137,159,000 ) (115,007,000 ) Total deferred tax assets 8,070,000 1,243,000 Deferred tax liabilities: Acquired intangibles (160,000 ) (142,000 ) Investment in affiliated entity — (4,000 ) Right of use asset (2,894,000 ) — Note discount (2,862,000 ) — Convertible note (1,381,000 ) — Fixed assets (805,000 ) (1,121,000 ) Net deferred tax liabilities $ (32,000 ) $ (24,000 ) As of December 31, 2019 , the Company had federal, California and Pennsylvania tax net operating loss (NOL) carryforwards of $483.3 million , $68.6 million and $80.5 million , respectively, net of the net operating losses that will expire due to IRC Section 382 limitations. The federal net operating loss generated in 2018 and 2019 of $186.6 million will carryforward indefinitely and be available to offset up to 80% of future taxable income each year. The federal NOL carryforward began to expire in 2020 , and the California and Pennsylvania NOL carryforwards will begin to expire in 2028 and 2021 , respectively, unless previously utilized. In addition, as of December 31, 2019, the Company had federal and state research and development (R&D) tax credit carryforwards of $17.3 million and $3.2 million , respectively. The federal tax credit carryforwards will begin to expire in 2029. The California research tax credits do not expire. Based upon statute, federal and state losses and credits are expected to expire as follows (in millions): Expiration Date: Federal NOLs State NOLs Federal R&D State R&D 2020 $ 1.6 $ — $ — $ — 2021 2.3 0.3 — — 2022 6.0 0.3 — — 2023 4.5 0.4 — — 2024 and thereafter 282.3 148.1 17.3 — Indefinite 186.6 — — 3.2 $ 483.3 $ 149.1 $ 17.3 $ 3.2 Pursuant to Internal Revenue Code (IRC) Sections 382 and 383, annual use of the Company’s NOL and R&D credit carryforwards may be limited in the event that a cumulative change in ownership of more than 50% occurs within a three-year period. The Company has completed an IRC Section 382/383 analysis, regarding the limitation of NOL and R&D credit carryforwards as of December 31, 2019. As a result of the analysis, the Company estimates that approximately $10.6 million of tax benefits related to NOL and R&D carryforwards will expire unused. Accordingly, the related NOL and R&D credit carryforwards have been removed from deferred tax assets, accompanied by a corresponding reduction of the valuation allowance. Due to the existence of the valuation allowance, limitations created by current and future ownership changes, if any, related to the Company's operations in the United States will not impact its effective tax rate. Any additional ownership changes may further limit the ability to use the NOL and R&D carryforwards. The following table summarizes the activity related to the Company's unrecognized tax benefits: Year ended December 31, 2019 2018 2017 Balance at beginning of the year $ 9,632,000 $ 8,313,000 $ 6,855,000 Increases related to current year tax positions 1,575,000 1,319,000 1,532,000 Increases (decreases) related to prior year tax positions (3,000 ) — (74,000 ) Balance at end of the year $ 11,204,000 $ 9,632,000 $ 8,313,000 The amount of unrecognized tax benefits that, if recognized and realized, would affect the effective tax rate was $9.9 million , $8.3 million and $7.1 million as of December 31, 2019 , 2018 and 2017 , respectively, subject to valuation allowances. The Company has not recorded any interest and penalties on the unrecognized tax positions as the Company has continued to generate net operating losses after accounting for the unrecognized tax benefits. The Company does not anticipate that the total amount of unrecognized tax benefits will significantly increase or decrease within twelve months of the reporting date. The Company and its subsidiaries are subject to U.S. federal income tax as well as income tax in multiple state jurisdictions. With few exceptions, the Company is no longer subject to United States federal income tax examinations for years before 2016 and state and local income tax examinations before 2015. However, to the extent allowed by law, the tax authorities may have the right to examine prior periods where net operating losses were generated and carried forward, and make adjustments up to the amount of the NOL carryforward amount. The Company is not currently under Internal Revenue Service (“IRS”), state or local tax examination.

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
401(k) Plan	401(k) Plan The Company has adopted a 401(k) Profit Sharing Plan covering substantially all of its employees. The defined contribution plan allows the employees to contribute a percentage of their compensation each year. The Company currently matches 50% of its employees’ contributions, up to 6% of their annual compensation. The Company’s contributions are recorded as expense in the accompanying consolidated statements of operations and totaled $1.2 million , $1.2 million and $822,000 for the years ended December 31, 2019 , 2018 and 2017 , respectively.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2019
Related Party Transaction, Due from (to) Related Party [Abstract]
Related Party Transactions	Related Party Transactions GeneOne Life Sciences The Company owned 1,644,155 shares of common stock in GeneOne as of December 31, 2019 and one of the Company's directors, Dr. David B. Weiner, acts as a consultant to GeneOne. In 2010, the Company entered into a collaboration and license agreement (the “GeneOne Agreement”) with GeneOne. Under the GeneOne Agreement, the Company granted GeneOne an exclusive license to the Company's SynCon ® universal influenza vaccine delivered with electroporation to be developed in certain countries in Asia (the “Product”). As consideration for the license granted to GeneOne, the Company received an upfront payment of $3.0 million , and is entitled to receive research support, annual license maintenance fees and royalties on net Product sales. The GeneOne Agreement also provides the Company with exclusive rights to supply devices for clinical and commercial purposes (including single use components) to GeneOne for use in the Product. The term of the GeneOne Agreement commenced upon execution and will extend on a country by country basis until the last to expire of all Royalty Periods for the territory (as such term is defined in the GeneOne Agreement) for any Product in that country, unless the GeneOne Agreement is terminated earlier in accordance with its provisions as a result of breach, by mutual agreement, or by GeneOne's right to terminate without cause upon prior written notice. In 2011, the Company entered into a collaborative development and license agreement (the “Hep Agreement”) with GeneOne. Under the Hep Agreement, as originally executed, the Company and GeneOne agreed to co-develop the Company’s SynCon ® therapeutic vaccines for hepatitis B and C infections (the “Hep Products”). Under the terms of the Hep Agreement, GeneOne will receive marketing rights for the Products in Asia, excluding Japan, and in return will fully fund IND-enabling and initial Phase 1 and 2 clinical studies with respect to the Hep Products. The Company will receive from GeneOne payments based on the achievement of clinical milestones and royalties based on sales of the Hep Products in the licensed territories, retaining all commercial rights to the Hep Products in all other territories. In 2013, the Company amended the Hep Agreement to grant back to the Company the SynCon ® therapeutic vaccines targeting hepatitis B, along with all associated rights, from the collaboration in return for certain remuneration including a percentage of license fees. In 2013, the Company further amended the Hep Agreement to in part provide exclusive patent rights to IL-28 technology for use with the Hep Products in Asia, excluding Japan. The Hep Agreement shall terminate upon the later of the expiration or abandonment of the last patent that is a component of the rights or 20 years after the effective date. In May 2015, the Company entered into a Collaborative Development Agreement with GeneOne to co-develop a DNA vaccine for MERS through Phase 1 clinical trials. Under the terms of the agreement, GeneOne will be responsible for funding all preclinical and clinical studies through Phase 1. In return, GeneOne will receive up to a 35% milestone-based ownership interest in the MERS immunotherapy asset upon achievement of the last milestone event of completion of the Phase 1 safety and immunogenicity study. The collaborative research program shall terminate upon the completion of activities under the development plan, unless sooner terminated. In January 2016, the Company and GeneOne amended the Collaborative Development Agreement for MERS to expand the agreement to test and advance the Company's DNA-based vaccine for preventing and treating Zika virus. GeneOne will be responsible for funding all preclinical and clinical studies through Phase 1. In return, GeneOne will receive up to a 35% milestone-based ownership interest in the Zika immunotherapy asset upon achievement of the last milestone event of the completion of the Phase 1 safety and immunogenicity study. All other agreement terms remain the same. In December 2017, the Company completed the sale of certain assets related to its compound VGX-1027 to GeneOne for a purchase price of $1.0 million . Revenue recognized from GeneOne for the years ended December 31, 2019 , 2018 and 2017 consisting of patent, device maintenance and licensing fees was $127,000 , $342,000 and $551,000 , respectively. Operating expenses recorded from transactions with GeneOne relate primarily to biologics manufacturing and were $2.5 million , $7.0 million and $2.3 million for the years ended December 31, 2019 , 2018 and 2017 , respectively. At December 31, 2019 and 2018 , the Company had an accounts receivable balance of $128,000 and $0 , respectively, and an accounts payable and accrued liability balance of $511,000 and $372,000 , respectively, related to GeneOne and its subsidiaries. At December 31, 2019 and 2018 , $284,000 and $381,000 , respectively, of prepayments made to GeneOne were classified as long-term other assets on the consolidated balance sheets. Plumbline Life Sciences, Inc. The Company owned 395,758 shares of common stock in Plumbline Life Sciences, Inc. ("PLS") as of December 31, 2019 and one of the Company's directors, Dr. David B. Weiner, acts as a consultant to PLS. Revenue recognized from PLS consists of license fees. For the years ended December 31, 2019 and 2018 , the Company recognized revenue from PLS of $111,000 and $107,000 , respectively. At December 31, 2019 and 2018 , the Company had an accounts receivable balance of $589,000 and $478,000 , respectively, related to PLS. The Wistar Institute Two of the Company's directors as of December 31, 2019, Dr. David B. Weiner and Dr. Morton Collins, were directors of the Vaccine Center of The Wistar Institute ("Wistar"). Dr. Weiner is also the Executive Vice President of Wistar. Dr. Collins retired from the Company's Board of Directors effective January 14, 2020. In March 2016, the Company entered into collaborative research agreements with Wistar for preventive and therapeutic DNA-based immunotherapy applications and products developed by Dr. Weiner and Wistar for the treatment of cancers and infectious diseases. Under the terms of the agreement, the Company will reimburse Wistar for all direct and indirect costs incurred in the conduct of the collaborative research, not to exceed $3.1 million during the five -year term of the agreement. The Company will have the exclusive right to in-license new intellectual property developed in this agreement. In November 2016, the Company received a $6.1 million sub-grant through Wistar to develop a DNA-based monoclonal antibody against the Zika infection, with funding through July 2020. The Company is also a collaborator with Wistar on an Integrated Preclinical/Clinical AIDS Vaccine Development grant from the NIAID, with funding through February 2020. A grant funding liability recognized from Wistar and recorded as contra-research and development expense is related to work performed by the Company on the research sub-contract agreements. For the years ended December 31, 2019 and 2018 , the Company recorded $2.2 million and $3.3 million , respectively, as contra-research and development expense from Wistar. Research and development expenses recorded from Wistar relate primarily to the collaborative research agreements and sub-contract agreements related to the Bill and Melinda Gates Foundation and CEPI (see Note 4). Research and development expenses recorded from Wistar for the years ended December 31, 2019 and 2018 were $1.5 million and $1.8 million, respectively. At December 31, 2019 and 2018 , the Company had an accounts receivable balance of $616,000 and $258,000 , respectively, and an accounts payable and accrued liability balance of $219,000 and $554,000 , respectively, related to Wistar. As of December 31, 2019 , the Company had $843,000 recorded as grant funding liability on its consolidated balance sheet related to Wistar.

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited) The following is a summary of the quarterly results of operations of the Company for the years ended December 31, 2019 and 2018 (unaudited): Quarter Ended Quarter Ended Quarter Ended Quarter Ended December 31, September 30, June 30, March 31, Consolidated Statements of Operations: Revenues: Revenue under collaborative research and development arrangements $ 184,523 $ 617,427 $ 64,283 $ 2,770,712 Revenue under collaborative research and development arrangements with affiliated entities 55,665 53,014 71,390 55,579 Miscellaneous revenue, including from affiliated entities 39,300 196,422 — 3,614 Total revenues 279,488 866,863 135,673 2,829,905 Operating Expenses: Research and development 22,003,955 19,137,209 22,486,266 24,389,888 General and administrative 8,696,586 5,681,441 5,850,101 6,975,029 Total operating expenses 30,700,541 24,818,650 28,336,367 31,364,917 Loss from operations (30,421,053 ) (23,951,787 ) (28,200,694 ) (28,535,012 ) Interest income 587,679 637,438 755,330 625,535 Interest expense (2,668,837 ) (2,428,671 ) (2,194,783 ) (656,248 ) Change in fair value of derivative liability (4,315,105 ) 2,551,453 — — Loss on investment in affiliated entities (1,681,401 ) (485,841 ) (173,212 ) (750,103 ) Other income (expense), net 263,571 140,956 127,512 (35,839 ) Net loss before income tax benefit $ (38,235,146 ) $ (23,536,452 ) $ (29,685,847 ) $ (29,351,667 ) Income tax benefit 87,764 — 106,771 62,800 Net loss $ (38,147,382 ) $ (23,536,452 ) $ (29,579,076 ) $ (29,288,867 ) Net loss attributable to non-controlling interest 485,344 445,759 191,850 69,605 Net loss attributable to Inovio Pharmaceuticals, Inc. $ (37,662,038 ) $ (23,090,693 ) $ (29,387,226 ) $ (29,219,262 ) Net loss per share Basic $ (0.38 ) $ (0.23 ) $ (0.30 ) $ (0.30 ) Diluted $ (0.38 ) $ (0.25 ) $ (0.30 ) $ (0.30 ) Quarter Ended Quarter Ended Quarter Ended Quarter Ended December 31, September 30, June 30, March 31, Consolidated Statements of Operations: Revenues: Revenue under collaborative research and development arrangements $ 2,372,600 $ 1,813,287 $ 24,385,852 $ 1,289,046 Revenue under collaborative research and development arrangements with affiliated entity 56,207 184,990 60,319 148,008 Miscellaneous revenue 73,817 2,591 2,590 92,590 Total revenues 2,502,624 2,000,868 24,448,761 1,529,644 Operating Expenses: Research and development 26,365,647 21,851,858 22,462,620 24,577,751 General and administrative 5,636,141 6,791,693 7,189,310 9,698,015 Total operating expenses 32,001,788 28,643,551 29,651,930 34,275,766 Loss from operations (29,499,164 ) (26,642,683 ) (5,203,169 ) (32,746,122 ) Interest and other income, net (169,300 ) 380,987 396,681 312,523 Change in fair value of common stock warrants — 228,665 259,971 (127,841 ) Gain (loss) from investment in affiliated entities (3,293,741 ) 1,017,359 (2,092,608 ) 2,380,423 Net loss before provision for income taxes (32,962,205 ) (25,015,672 ) (6,639,125 ) (30,181,017 ) Provision for income taxes — — — (2,169,811 ) Net loss (32,962,205 ) (25,015,672 ) (6,639,125 ) (32,350,828 ) Net loss per share Basic $ (0.34 ) $ (0.27 ) $ (0.07 ) $ (0.36 ) Diluted $ (0.34 ) $ (0.27 ) $ (0.08 ) $ (0.36 )

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On February 7, 2020, the Company entered into an amendment to the Sales Agreement, which amendment increased the amount of common stock that could be sold by the Company under the Sales Agreement from an aggregate offering price of up to $100.0 million to an aggregate offering price of up to $200.0 million . On March 9, 2020, the Company entered into a second amendment to the Sales Agreement, which amendment increased the amount of common stock that could be sold by the Company under the Sales Agreement from an aggregate offering price of up to $200.0 million to an aggregate offering price of up to $250.0 million . Under the Sales Agreement, as amended, the Company set the parameters for the sale of shares, including the number of shares to be issued, the time period during which sales were requested to be made, limitation on the number of shares that could be sold in any one trading day and any minimum price below which sales could not be made. The Sales Agreement provided that the Placement Agent is entitled to compensation for its services in an amount equal to up to 3.0% of the gross proceeds from the sales of shares sold through the Placement Agent under the Sales Agreement. From January 1, 2020 through March 11, 2020 , the Company sold 43,148,952 shares of common stock under its Sales Agreement for net proceeds of $208.2 million. The sales were made at a weighted average price of $4.92 per share. As of the date these financial statements were issued, there is no remaining capacity under the Sales Agreement, as amended. On February 20, 2020, the Company entered into a Debt and Share Subscription Agreement with PLS under which the Company will receive shares of PLS common stock in exchange for a portion of the outstanding accounts receivable balance due from PLS. Following the issuance of these shares, the Company will hold a 19.9% ownership interest in PLS.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Inovio incurred a net loss attributable to common stockholders of $119.4 million for the year ended December 31, 2019 . Inovio had working capital of $62.2 million and an accumulated deficit of $739.8 million as of December 31, 2019 . The Company has incurred losses in each year since its inception and expects to continue to incur significant expenses and operating losses for the foreseeable future in connection with the research and preclinical and clinical development of its product candidates. During the year ended December 31, 2019, the Company received net proceeds of $75.7 million from a private placement of $78.5 million aggregate principal amount of its 6.50% convertible senior notes due 2024 (the “Notes”), net proceeds of $14.5 million from the private placement of 18 billion Korean Won (KRW) (approximately USD $15.0 million based on the exchange rate on the date of issuance) aggregate principal amount of its 1.0% convertible bonds due August 2024 (the "August 2019 Bonds"), net proceeds of $4.0 million from the private placement of 4.7 billion KRW (approximately USD $4.1 million based on the exchange rate on the date of issuance) aggregate principal amount of its 1.0% convertible bonds due December 2024 (the "December 2019 Bonds" and, collectively with the August 2019 Bonds, the “Bonds”) and net proceeds of $9.1 million from sales of common stock under its At-the-Market Equity Offering Sales Agreement with Stifel, Nicolaus & Company (the “Sales Agreement”). As described in Note 19 below, the Sales Agreement was amended subsequent to December 31, 2019. From January 1, 2020 through March 11, 2020 , the Company sold 43,148,952 shares of common stock under the Sales Agreement, as amended, for net proceeds of $208.2 million. These proceeds, in addition to the Company’s cash, cash equivalents and short-term investments of $ 89.5 million and long-term investments of $ 6.3 million as of December 31, 2019 , are sufficient to support the Company's operations for a period of at least 12 months from the date it issued these financial statements. In order to continue to fund future research and development activities, the Company will need to seek additional capital. This may occur through strategic alliance and licensing arrangements and/or future public or private debt or equity financings including use of its Sales Agreement. However, sufficient funding may not be available in the future, or if available, may be on terms that significantly dilute or otherwise adversely affect the rights of existing stockholders. If adequate funds are not available, the Company may need to delay, reduce the scope of or put on hold one or more of its clinical and/or preclinical programs. In July 2019, the Company announced a strategic organizational restructuring. In order to reduce operating expenses and conserve cash resources, the Company reduced its workforce by approximately 28% and discontinued its Phase 1/2 clinical trial of its immuno-oncology product candidate INO-5401 in patients with advanced bladder cancer. In the third quarter of 2019, the Company incurred a personnel-related restructuring charge of $2.2 million in connection with one-time employee termination costs, including severance and other benefits, all of which have been paid as of December 31, 2019. The Company’s ability to continue its operations is dependent upon its ability to obtain additional capital in the future and achieve profitable operations. The Company expects to continue to rely on outside sources of financing to meet its capital needs and the Company may never achieve positive cash flow. These consolidated financial statements do not include any adjustments to the specific amounts and classifications of assets and liabilities, which might be necessary should Inovio be unable to continue as a going concern. Inovio’s consolidated financial statements as of and for the year ended December 31, 2019 have been prepared on a going concern basis, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business for the foreseeable future. The Company has evaluated subsequent events after the balance sheet date through the date it issued these financial statements.
Consolidation	Consolidation These consolidated financial statements include the accounts of Inovio Pharmaceuticals, Inc. and its subsidiaries. The Company consolidates its wholly-owned subsidiaries Genetronics, Inc. and VGX Pharmaceuticals Inc. ("VGX"), and records a non-controlling interest for 39% of its subsidiary Geneos Therapeutics, Inc. ("Geneos") as well as 15% of VGX Animal Health, Inc., a subsidiary of VGX. All intercompany accounts and transactions have been eliminated upon consolidation.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one segment operating primarily within the United States.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosures of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and short-term investments. The Company limits its exposure to credit loss by placing its cash and investments with high credit quality financial institutions. Additionally, the Company has established guidelines regarding diversification of its investments and their maturities which are designed to maintain principal and maximize liquidity.
Fair value of Financial Instruments	Fair value of Financial Instruments The Company’s financial instruments consist principally of cash equivalents, short-term investments and investments in affiliated entities. The carrying amounts of cash equivalents approximate the related fair values due to the short-term maturities of these instruments. Investments are recorded at fair value, based on current market valuations. After the adoption of Accounting Standards Update ("ASU") No. 2016-01 on January 1, 2018, unrealized gains and losses on the Company's equity investment in its affiliated entity Plumbline Life Sciences, Inc. ("PLS") are reported in the consolidated statement of operations as a gain (loss) on investment in affiliated entities. The Company’s investment in GeneOne, an affiliated entity, is accounted for at fair value on a recurring basis, with changes in fair value recorded on the consolidated statements of operations within gain (loss) from investment in affiliated entity. The Company carries convertible notes and bonds at face value less unamortized debt discount and issuance costs on its consolidated balance sheet, and it presents the fair value of such convertible notes and bonds for disclosure purposes only.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents are considered by the Company to be highly liquid investments purchased with original maturities of three months or less from the date of purchase. Cash and cash equivalents included certain money market accounts at December 31, 2019 and 2018 .
Investments	Investments The Company defines investments as income-yielding securities that can be readily converted into cash or equity investments classified as available-for-sale. Investments included mutual funds and equity investments in the Company’s affiliated entities, PLS and GeneOne, at December 31, 2019 . Investments included mutual funds, United States corporate debt securities and an equity investment in the Company's affiliated entities, PLS and GeneOne, at December 31, 2018 .
Accounts Receivable	Accounts Receivable Accounts receivable are recorded at invoiced amounts and do not bear interest. The Company performs ongoing credit evaluations of its customers’ financial condition. Credit is extended to customers as deemed necessary and generally does not require collateral. Management believes that the risk of loss is significantly reduced due to the quality and financial position of the Company's customers.
Fixed Assets	Fixed Assets Property and equipment are stated at cost and depreciated using the straight-line method over the estimated useful life of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the remaining term of the related leases or the estimated economic useful lives of the improvements. Repairs and maintenance are expensed as incurred.
Long-Lived Assets	Long-Lived Assets All long-lived assets are reviewed for impairment in value when changes in circumstances dictate, based upon undiscounted future operating cash flows, and appropriate losses are recognized and reflected in current earnings, to the extent the carrying amount of an asset exceeds its estimated fair value determined by the use of appraisals, discounted cash flow analyses or comparable fair values of similar assets.
Valuation of Intangible Assets and Goodwill	Valuation of Intangible Assets and Goodwill Intangible assets are amortized over their estimated useful lives ranging from two to 18 years . Acquired intangible assets are continuously being developed for the future economic viability contemplated at the time of acquisition. The Company is concurrently conducting preclinical studies and clinical trials using the acquired intangibles and has entered into licensing agreements for the use of these acquired intangibles. Historically, the Company has recorded patents at cost and amortized these costs using the straight-line method over the expected useful lives of the patents or 17 years , whichever is less. Patent cost consists of the consideration paid for patents and related legal costs. Effective as of the acquisition of VGX in 2009, all new patent costs are expensed as incurred, with patent costs capitalized as of that date continuing to be amortized over the expected life of the patent. License costs are recorded based on the fair value of consideration paid and are amortized using the straight-line method over the shorter of the expected useful life of the underlying patents or the term of the related license agreement to the extent the license has an alternative future use. As of December 31, 2019 and 2018, the Company’s intangible assets resulting from the acquisition of VGX, as well as the acquisitions of two other companies, Inovio AS and Bioject Medical Technologies, Inc. ("Bioject"), and additional intangibles including previously capitalized patent costs and license costs, net of accumulated amortization, totaled $3.7 million and $4.8 million , respectively. The determination of the value of intangible assets requires management to make estimates and assumptions that affect the Company’s consolidated financial statements. The Company assesses potential impairments to intangible assets when there is evidence that events or changes in circumstances indicate that the carrying amount of an asset may not be recovered. The Company’s judgments regarding the existence of impairment indicators and future cash flows related to intangible assets are based on operational performance of its acquired businesses, market conditions and other factors. If impairment is indicated, the Company will reduce the carrying value of the intangible asset to fair value. While current and historical operating and cash flow losses are potential indicators of impairment, the Company believes the future cash flows to be received from its intangible assets will exceed the intangible assets’ carrying value, and accordingly, the Company has not recognized any impairment losses through December 31, 2019. Goodwill represents the excess of acquisition cost over the fair value of the net assets of acquired businesses. Goodwill is reviewed for impairment at least annually at November 30, or more frequently if an event occurs indicating the potential for impairment. During its goodwill impairment review, the Company may assess qualitative factors to determine whether it is more likely than not that the fair value of its reporting unit is less than its carrying amount, including goodwill. The qualitative factors include, but are not limited to, macroeconomic conditions, industry and market considerations, and the overall financial performance of the Company. If, after assessing the totality of these qualitative factors, the Company determines that it is not more likely than not that the fair value of its reporting unit is less than its carrying amount, then no additional assessment is deemed necessary. Otherwise, the Company proceeds to perform the two-step test for goodwill impairment. The first step involves comparing the estimated fair value of the reporting unit with its carrying value, including goodwill. If the carrying amount of the reporting unit exceeds its fair value, the Company performs the second step of the goodwill impairment test to determine the amount of loss, which involves comparing the implied fair value of the goodwill to the carrying value of the goodwill. The Company may also elect to bypass the qualitative assessment in a period and elect to proceed to perform the first step of the goodwill impairment test. The Company performed its annual assessment for goodwill impairment as of November 30, 2019, identifying no impairment. Although there are inherent uncertainties in this assessment process, the estimates and assumptions the Company is using are consistent with its internal planning. If these estimates or their related assumptions change in the future, the Company may be required to record an impairment charge on all or a portion of its goodwill and intangible assets. Furthermore, the Company cannot predict the occurrence of future impairment triggering events nor the impact such events might have on its reported asset values. Future events could cause the Company to conclude that impairment indicators exist and that goodwill or other intangible assets associated with its acquired businesses are impaired. Any resulting impairment loss could have an adverse impact on the Company’s results of operations.
Income Taxes	Income Taxes The Company recognizes deferred tax assets and liabilities for temporary differences between the financial reporting basis and the tax basis of the Company’s assets and liabilities along with net operating loss and tax credit carry forwards. The Company records a valuation allowance against its deferred tax assets to reduce the net carrying value to an amount that it believes is more likely than not to be realized. When the Company establishes or reduces the valuation allowance against its deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made. Valuation allowances against the Company’s deferred tax assets were $137.2 million and $115.0 million at December 31, 2019 and 2018 , respectively. Changes in the valuation allowances, when they are recognized in the provision for income taxes, are included as a component of the estimated annual effective tax rate.
Collaboration Agreements	Collaboration Agreements The Company assesses whether its collaboration agreements are subject to Accounting Standards Codification ("ASC") 808: Collaborative Arrangements (“Topic 808”) based on whether they involve joint operating activities and whether both parties have active participation in the arrangement and are exposed to significant risks and rewards. To the extent that the arrangement falls within the scope of Topic 808, the Company assesses whether the payments between the Company and the collaboration partner are subject to other accounting literature. If payments from the collaboration partner to the Company represent consideration from a customer, then the Company accounts for those payments within the scope of Topic 606. However, if the Company concludes that its collaboration partner is not a customer for certain activities, such as for certain collaborative research and development activities, the Company presents such payments as a reduction of research and development expense.
Revenue Recognition	Revenue Recognition Effective January 1, 2018, the Company adopted ASU 2014-09, Revenue from Contracts with Customers (“Topic 606”) using the modified retrospective method which consisted of applying and recognizing the cumulative effect of Topic 606 at the date of initial application. The Company recognizes revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. To determine revenue recognition for contracts with customers, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Company satisfies its performance obligations. At contract inception, the Company assesses the goods or services agreed upon within each contract and assess whether each good or service is distinct and determine those that are performance obligations. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Collaborative Arrangements The Company enters into collaborative arrangements with partners that typically include payment of one or more of the following: (i) license fees; (ii) product supply services; (iii) milestone payments related to the achievement of developmental, regulatory, or commercial goals; and (iv) royalties on net sales of licensed products. Where a portion of non-refundable, upfront fees or other payments received are allocated to continuing performance obligations under the terms of a collaborative arrangement, they are recorded as deferred revenue and recognized as revenue when (or as) the underlying performance obligation is satisfied. As part of the accounting for these arrangements, the Company must develop estimates and assumptions that require judgment of management to determine the underlying stand-alone selling price for each performance obligation which determines how the transaction price is allocated among the performance obligation. The standalone selling price may include items such as forecasted revenues, development timelines, discount rates and probabilities of technical and regulatory success. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. License Fees If a license to intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Product Supply Services Arrangements that include a promise for future supply of drug product for either clinical development or commercial supply at the licensee’s discretion are generally considered as options. The Company assesses if these options provide a material right to the licensee and if so, they are accounted for as separate performance obligations. The Company evaluates whether it is the principal or agent in the arrangement. The Company had determined that it is the principal in the current arrangements as the Company controls the product supply before it is transferred to the customer. Milestone Payments At the inception of each arrangement that includes milestone payments (variable consideration), the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company's or its collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achieving such milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Royalties For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and for which the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaborative arrangements.
Grants	Grants The Company has determined that as of January 1, 2018, accounting for the Company’s various grant agreements falls under the contributions guidance under Subtopic 958-605, Not-for-Profit Entities-Revenue Recognition , which is outside the scope of Topic 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. Beginning on January 1, 2018, all contributions received from current grant agreements are recorded as a contra- expense as opposed to revenue on the consolidated statement of operations.
Derivative Liabilities	Derivative Liabilities The Company evaluates its debt and equity issuances to determine if those contracts or embedded components of those contracts qualify as derivatives requiring separate recognition in the Company's financial statements. The result of this accounting treatment is that the fair value of the embedded derivative is revalued at each balance sheet date and recorded as a liability, and the change in fair value during the reporting period is recorded in other income (expense) in the consolidated statements of operations. In circumstances where the embedded conversion option in a convertible instrument is required to be bifurcated and there are also other embedded derivative instruments in the convertible instrument that are required to be bifurcated, the bifurcated derivative instruments are accounted for as a single, compound derivative instrument. The classification of derivative instruments, including whether such instruments should be recorded as liabilities or as equity, is reassessed at the end of each reporting period. Derivative instrument liabilities are classified in the balance sheet as current or non-current based on whether or not net-cash settlement of the derivative instrument is expected within twelve months of the balance sheet date.
Foreign Currency Transactions	Foreign Currency Transactions The functional and presentation currency of the Company is the U.S. dollar. Transactions denominated in a currency other than the functional currency are recorded on the initial recognition at the exchange rate at the date of the transaction. After initial recognition, monetary assets and liabilities denominated in foreign currency are remeasured at the end of each reporting period into the functional currency at the exchange rate at that date. Exchange differences are included in general and administrative expenses in the consolidated statement of operations. Non-monetary assets and liabilities measured at cost are remeasured at the exchange rate at the date of the transaction.
Research and Development Expenses	Research and Development Expenses The Company’s activities have largely consisted of research and development efforts related to developing electroporation delivery technologies and DNA immunotherapies and vaccines. Research and development expenses consist of expenses incurred in performing research and development activities including salaries and benefits, facilities and other overhead expenses, clinical trials, contract services and other outside expenses. Research and development expenses are charged to operations as they are incurred. These expenses result from the Company's independent research and development efforts as well as efforts associated with collaborations and licensing arrangements. The Company reviews and accrues clinical trial expense based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of studies and other events. The Company follows this method since reasonably dependable estimates of the costs applicable to various stages of a research agreement or clinical trial can be made. Accrued clinical trial costs are subject to revisions as trials progress. Revisions are charged to expense in the period in which the facts that give rise to the revision become known. Historically, revisions have not resulted in material changes to research and development expense; however, a modification in the protocol of a clinical trial or cancellation of a trial could result in a charge to the Company's results of operations.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss for the year by the weighted average number of common shares outstanding during the year. Diluted net loss per share is calculated in accordance with the treasury stock method for the outstanding stock options, restricted stock units and warrants and reflects the potential dilution that would occur if securities or other contracts to issue common stock were exercised or converted to common stock. For the year ended December 31, 2019, the dilutive impact of the outstanding Notes and Bonds issued by the Company (discussed in Note 10) has been considered using the "if-converted" method. The calculation of diluted net loss per share requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the options or other securities and the presumed exercise of such securities are dilutive to net loss per share for the period, an adjustment to net loss used in the calculation is required to remove the change in fair value of such securities from the numerator for the period. Likewise, an adjustment to the denominator is required to reflect the related dilutive shares, if any.
Leases	Leases The Company adopted ASU 2016‑02, Leases (Topic 842) (“Topic 842”) on January 1, 2019. For long-term operating leases, the Company recognized an operating lease right-of-use asset and an operating lease liability on its consolidated balance sheets. The lease liability is determined as the present value of future lease payments using an estimated rate of interest that the Company would pay to borrow equivalent funds on a collateralized basis at the lease commencement date. The right-of-use asset is based on the liability adjusted for any prepaid or deferred rent. The Company determined the lease term at the commencement date by considering whether renewal options and termination options are reasonably assured of exercise. Fixed rent expense for the Company's operating leases is recognized on a straight-line basis over the term of the lease and is included in operating expenses on the consolidated statements of operations. Variable lease payments including lease operating expenses are recorded as incurred. Prior period amounts continue to be reported in accordance with the historic accounting under the previous lease guidance, ASC 840, Leases (Topic 840). See “Recent Accounting Pronouncements - Recently Adopted” below, for more information about the impact of the adoption of Topic 842.
Stock-Based Compensation	Stock-Based Compensation The Company incurs stock-based compensation expense related to restricted stock units and stock options. The fair value of restricted stock is determined by the closing price of the Company's common stock reported on the Nasdaq Global Select Market on the date of grant. The Company estimates the fair value of stock options granted using the Black-Scholes option pricing model. The Black-Scholes option pricing model was developed for use in estimating the fair value of traded options, which have no vesting restrictions and are fully transferable. In addition, option valuation models require the input of subjective assumptions, including the expected stock price volatility and expected option life. The Company amortizes the fair value of the awards on a straight-line basis over the requisite vesting period of the awards. Expected volatility is based on historical volatility. The expected life of options granted is based on historical expected life. The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant. The dividend yield is based on the fact that no dividends have been paid historically and none are currently expected to be paid in the foreseeable future. The Company recognizes forfeitures as they occur.
Recent Accounting Pronouncements - Recently Adopted, Recent Accounting Pronouncements	Recent Accounting Pronouncements - Recently Adopted The recent accounting pronouncements below may have a significant effect on the Company's financial statements. Recent accounting pronouncements that are not anticipated to have an impact on or are unrelated to the Company's financial condition, results of operations, or related disclosures are not discussed. ASU No. 2016-02 . In February 2016, the FASB issued Topic 842, which requires lessees to recognize most leases on the balance sheet as lease liabilities with corresponding right-of-use assets and to disclose key information about leasing arrangements. The Company adopted the new lease standard on January 1, 2019 using the modified retrospective approach. The Company elected the available package of practical expedients upon adoption, which allowed the Company to carry forward its historical assessment of whether existing agreements contained a lease and the classification of its existing operating leases. Upon adoption, the Company recognized an operating right-of use asset and operating lease liability in its consolidated balance sheet of approximately $14.6 million and $24.2 million , respectively. The Company also classified deferred rent of $9.6 million as an offset to the Company’s operating right-of-use asset upon adoption. There were no adjustments to the Company’s opening accumulated deficit balance upon adoption. The impact of the adoption of Topic 842 on the consolidated balance sheets as of January 1, 2019 was as follows: ASC 840 Topic 842 January 1, 2019 Impact of Adoption January 1, 2019 Deferred rent, current portion $ 1,065,387 $ (1,065,387 ) $ — Deferred rent, non-current portion $ 8,518,207 $ (8,518,207 ) $ — Operating right-of-use assets $ — $ 14,634,769 $ 14,634,769 Operating lease liability, current portion $ — $ 1,733,600 $ 1,733,600 Operating lease liability, non-current portion $ — $ 22,484,763 $ 22,484,763 ASU No. 2018-07 . In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718), Improvements to Nonemployee Share-Based Payment Accounting, that simplifies the accounting for stock-based payments granted to non-employees for services by generally aligning it with the accounting for stock-based payments granted to employees. The Company adopted the standard on January 1, 2019 and there was no material impact to its consolidated financial statements. ASU No. 2018-13 . In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement Disclosure Framework-Changes to the Disclosure Requirements for Fair Value Measurement , which amends certain disclosure requirements over Level 1, Level 2 and Level 3 fair value measurements (see Note 6 for more information about the Company’s fair value classifications). ASU 2018-13 is effective for fiscal years beginning after December 15, 2019 and interim periods within those fiscal years. Early adoption is permitted. The Company does not expect the adoption of this standard to have a material impact on its disclosures. Recent Accounting Pronouncements - Not Yet Adopted ASU No. 2016-13 . In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments (Topic 326) , which amends the impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables and available for sale debt securities. ASU 2016-13 is effective beginning in the first quarter of 2020, with early adoption permitted. The Company is currently evaluating the impact of this ASU on its consolidated financial statements. This standard includes the Company's financial instruments, such as accounts receivable and investments that are generally of high credit quality. Previously, when credit losses were measured under GAAP, an entity generally only considered past events and current conditions in measuring the incurred loss. The new guidance requires the Company to identify, analyze, document and support new methodologies for quantifying expected credit loss estimates for its financial instruments, using information such as historical experience and current economic conditions, plus the use of reasonable supportable forecast information. ASU No. 2018-18 . In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 , which clarified the interaction between Topic 808, Collaborative Arrangements , and Topic 606, Revenue from Contracts with Customers . ASU 2018-18 is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption is permitted. The adoption of this standard is not expected to have a material impact on the financial statements. ASU 2017-04. In January 2017, the FASB issued ASU 2017-04, Intangibles - Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment ("ASU 2017-04"). ASU 2017-04 simplifies the recognition and measurement of a goodwill impairment loss by eliminating Step 2 of the quantitative goodwill impairment test. The guidance requires a one-step impairment test in which an entity compares the fair value of a reporting unit with its carrying amount and recognizes an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value, if any. ASU 2017-04 is effective for fiscal years beginning after December 15, 2019 and should be applied on a prospective basis. The Company adopted this guidance on January 1, 2020, and it believes the adoption of this guidance will not have a material impact on its consolidated financial statements or related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following tables reconcile the components of the numerator and denominator included in the calculations of diluted net loss per share: Year Ended December 31, 2019 2018 2017 Numerator Net loss attributable to Inovio Pharmaceuticals, Inc. (numerator for use in basic net loss per share) $ (119,359,219 ) $ (96,967,830 ) $ (88,205,772 ) Adjustment for decrease in fair value of warrant liability — — (806,819 ) Numerator for use in diluted net loss per share $ (119,359,219 ) $ (96,967,830 ) $ (89,012,591 ) Denominator Weighted average number of common shares outstanding (denominator for use in basic net loss per share) 98,717,999 92,539,997 81,777,493 Effect of dilutive potential common shares — — 140,529 Denominator for use in diluted net loss per share 98,717,999 92,539,997 81,918,022 Net loss per share, diluted $ (1.21 ) $ (1.05 ) $ (1.09 ) Net loss per share, basic $ (1.21 ) $ (1.05 ) $ (1.08 )
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect	The following table summarizes potential shares of common stock that were excluded from diluted net loss per share calculation because of their anti-dilutive effect: Year Ended December 31, 2019 2018 2017 Options to purchase common stock 9,265,390 8,752,677 7,694,870 Restricted stock units 2,069,936 1,688,017 1,234,168 Convertible preferred stock 8,456 8,456 8,456 Convertible notes 14,585,653 — — August 2019 Bonds 3,799,071 — — December 2019 Bonds 1,009,450 — — Total 30,737,956 10,449,150 8,937,494
Summary of assumptions used to estimate the fair value of stock options	The weighted average assumptions used in the Black-Scholes model for option grants to employees and directors are presented below: Year Ended December 31, 2019 2018 2017 Risk-free interest rate 2.42% 2.73% 2.20% Expected volatility 70% 72% 73% Expected life in years 6 6 6 Dividend yield — — — The weighted average assumptions used in the Black-Scholes model for option grants to non-employees are presented below: Year Ended December 31, 2019 2018 2017 Risk-free interest rate 2.45% 2.71% 2.42% Expected volatility 88% 78% 99% Expected life in years 10 9 9 Dividend yield — — —
Schedule of New Accounting Pronouncements and Changes in Accounting Principles	The impact of the adoption of Topic 842 on the consolidated balance sheets as of January 1, 2019 was as follows: ASC 840 Topic 842 January 1, 2019 Impact of Adoption January 1, 2019 Deferred rent, current portion $ 1,065,387 $ (1,065,387 ) $ — Deferred rent, non-current portion $ 8,518,207 $ (8,518,207 ) $ — Operating right-of-use assets $ — $ 14,634,769 $ 14,634,769 Operating lease liability, current portion $ — $ 1,733,600 $ 1,733,600 Operating lease liability, non-current portion $ — $ 22,484,763 $ 22,484,763

Short-term Investments (Tables)

Short-term Investments (Tables)	12 Months Ended
	Dec. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Summary of investments	The following is a summary of available-for-sale securities as of December 31, 2019 and 2018 : As of December 31, 2019 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 66,599,219 $ 754,709 $ (15,911 ) $ 67,338,017 As of December 31, 2018 Contractual Maturity (in years) Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Mutual funds --- $ 57,842,955 $ — $ (528,084 ) $ 57,314,871 US corporate debt securities Less than 2 224,633 — (652 ) 223,981 Total investments $ 58,067,588 $ — $ (528,736 ) $ 57,538,852

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Financial assets and liabilities measured at fair value on a recurring basis	The following table presents the Company’s assets and liabilities that are measured at fair value on a recurring basis, and are determined using the following inputs as of December 31, 2019 : Fair Value Measurements at December 31, 2019 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 2,349,729 $ 2,349,729 $ — $ — Mutual funds 67,338,017 — 67,338,017 — Investments in affiliated entities 6,315,356 6,315,356 — — Total assets $ 76,003,102 $ 8,665,085 $ 67,338,017 $ — Liabilities: Derivative liability (Note 10) $ 8,819,023 $ — $ — $ 8,819,023 Total liabilities $ 8,819,023 $ — $ — $ 8,819,023 The following table presents the Company’s assets that are measured at fair value on a recurring basis, and are determined using the following inputs as of December 31, 2018 : Fair Value Measurements at December 31, 2018 Total Quoted Prices in Active Markets (Level 1) Significant Other Unobservable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Money market funds $ 9,646,507 $ 9,646,507 $ — $ — Mutual funds 57,314,871 — 57,314,871 — US corporate debt securities 223,981 — 223,981 — Investments in affiliated entities 9,405,913 9,405,913 — — Total assets $ 76,591,272 $ 19,052,420 $ 57,538,852 $ —
Changes in fair value of the financial liabilities	The following table presents the changes in fair value of the derivative liability for the year ended December 31, 2019 : Balance at December 31, 2018 $ — Initial fair value upon issuance of the August 2019 Bonds 7,055,371 Change in fair value 1,763,652 Balance at December 31, 2019 $ 8,819,023 There were no Level 3 liabilities held as of December 31, 2018 .

Major Customers and Concentra_2

Major Customers and Concentration of Credit Risk (Tables)	12 Months Ended
	Dec. 31, 2019
Risks and Uncertainties [Abstract]
Schedule of major customers and concentration risks	Customer 2019 Revenue % of Total Revenue 2018 Revenue % of Total Revenue 2017 Revenue % of Total Revenue ApolloBio $ — — % $ 23,000,000 75 % $ — — % AstraZeneca 3,194,877 78 6,850,424 23 22,269,773 53 DARPA — — — — 9,983,927 24 Roche — — — — 6,107,254 14 All other, including affiliated entities 917,053 22 631,473 2 3,859,132 9 Total revenue $ 4,111,930 100 % $ 30,481,897 100 % $ 42,220,086 100 %

Fixed Assets (Tables)

Fixed Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Schedule of fixed assets	Fixed assets at December 31, 2019 and 2018 consist of the following: Cost Accumulated Depreciation and Amortization Net Book Value As of December 31, 2019 Leasehold improvements $ 15,007,935 $ (4,996,777 ) $ 10,011,158 Laboratory equipment 4,102,467 (3,229,357 ) 873,110 Office furniture and fixtures 3,048,053 (1,944,293 ) 1,103,760 Computer equipment and other 3,781,020 (2,996,031 ) 784,989 $ 25,939,475 $ (13,166,458 ) $ 12,773,017 As of December 31, 2018 Leasehold improvements $ 14,909,341 $ (3,464,444 ) $ 11,444,897 Laboratory equipment 4,031,965 (2,425,854 ) 1,606,111 Office furniture and fixtures 3,198,803 (1,767,653 ) 1,431,150 Computer equipment and other 3,808,824 (2,341,968 ) 1,466,856 $ 25,948,933 $ (9,999,919 ) $ 15,949,014

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Summary of intangible assets by major asset class	The following sets forth goodwill and intangible assets by major asset class: December 31, 2019 December 31, 2018 Weighted Average Useful Life (Yrs) Gross Accumulated Amortization Net Book Value Gross Accumulated Amortization Net Book Value Indefinite lived: Goodwill(a) $ 10,513,371 $ — $ 10,513,371 $ 10,513,371 $ — $ 10,513,371 Definite lived: Patents 10 5,802,528 (5,802,528 ) — 5,802,528 (5,742,079 ) 60,449 Licenses 10 1,323,761 (1,248,104 ) 75,657 1,323,761 (1,219,357 ) 104,404 CELLECTRA ® (b) 8 8,106,270 (8,106,270 ) — 8,106,270 (7,679,190 ) 427,080 GHRH(b) 11 335,314 (335,314 ) — 335,314 (303,630 ) 31,684 Bioject (c) 12 5,100,000 (2,175,556 ) 2,924,444 5,100,000 (1,882,222 ) 3,217,778 Other(d) 18 4,050,000 (3,356,250 ) 693,750 4,050,000 (3,131,250 ) 918,750 Total intangible assets 11 24,717,873 (21,024,022 ) 3,693,851 24,717,873 (19,957,728 ) 4,760,145 Total goodwill and intangible assets $ 35,231,244 $ (21,024,022 ) $ 14,207,222 $ 35,231,244 $ (19,957,728 ) $ 15,273,516 (a) Goodwill was recorded from the Inovio AS acquisition in January 2005, the acquisition of VGX in June 2009 and the acquisition of Bioject in April 2016 for $3.9 million , $6.2 million and $400,000 , respectively. (b) CELLECTRA ® and GHRH are developed technologies which were recorded from the acquisition of VGX. (c) Bioject intangible assets represent the estimated fair value of developed technology and intellectual property which were recorded from the Bioject asset acquisition. (d) Other intangible assets represent the estimated fair value of acquired intellectual property from the Inovio AS acquisition.
Schedule of finite-lived intangible assets, future amortization expense	Amortization expense related to intangible assets at December 31, 2019 is expected to be incurred as follows: Year ending December 31, 2020 $ 547,081 2021 520,414 2022 492,818 2023 275,760 2024 253,333 Thereafter 1,604,445 $ 3,693,851

Convertible Debt (Tables)

Convertible Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Convertible Debt	The balance of the Notes at December 31, 2019 is as follows: Principal amount $ 78,500,000 Unamortized debt discount on the liability component (14,082,302 ) Unamortized debt issuance cost (1,938,206 ) Accrued interest 1,700,833 Net carrying amount $ 64,180,325 The balance of the August 2019 Bonds at December 31, 2019 is as follows: Principal amount $ 15,578,211 Unamortized debt discount (6,764,346 ) Unamortized debt issuance cost (255,185 ) Accretion of premium associated with the August 2019 Bonds 227,322 Accrued interest 38,946 Net carrying amount $ 8,824,948 The balance of the December 2019 Bonds at December 31, 2019 is as follows: Principal amount $ 4,067,644 Unamortized debt issuance cost (50,000 ) Accretion of premium associated with the December 2019 Bonds — Accrued interest — Net carrying amount $ 4,017,644
Schedule of Maturities of Long-term Debt	As of December 31, 2019 , future minimum payments due under the Company's convertible debt instruments are as follows: Year ending December 31, Convertible Notes (1) August 2019 Bonds (2) December 2019 Bonds (2) Total 2020 $ 5,103,000 $ 156,000 $ 31,000 $ 5,290,000 2021 5,103,000 156,000 41,000 5,300,000 2022 5,103,000 156,000 41,000 5,300,000 2023 5,103,000 156,000 41,000 5,300,000 2024 81,051,000 20,021,000 5,236,000 106,308,000 Total $ 101,463,000 $ 20,645,000 $ 5,390,000 $ 127,498,000 (1) Amounts represent contractual amounts due under the Notes, including interest based on the fixed rate of 6.5% per year. (2) Amounts represent contractual amounts due under the August 2019 and December 2019 Bonds, including interest based on the fixed rate of 1% per year plus a premium on such bonds to provide an internal rate of return with respect to such Bonds of 6% at maturity.

Accounts Payable and Accrued _2

Accounts Payable and Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2019
Payables and Accruals [Abstract]
Schedule of accounts payable and accrued expenses	Accounts payable and accrued expenses at December 31, 2019 and 2018 consist of the following: As of December 31, 2019 2018 Trade accounts payable $ 6,919,081 $ 10,043,816 Accrued compensation 8,967,897 9,466,821 Accrued subcontract costs 273,508 83,812 Other accrued expenses 2,076,772 3,540,284 $ 18,237,258 $ 23,134,733

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Stockholders' Equity Note [Abstract]
Summary of preferred stock authorized, issued and outstanding	Shares Outstanding as of December 31, Shares Authorized Shares Issued 2019 2018 Series C Preferred Stock, par $0.001 1,091 1,091 23 23
Schedule of shares authorized under stock option plans, by exercise price range	The following table summarizes total stock options outstanding at December 31, 2019 : Options Outstanding Options Exercisable Exercise Price Shares Underlying Options Outstanding Weighted-Average Remaining Contractual Life (in Years) Weighted Average Exercise Price Shares Underlying Options Exercisable Weighted Average Exercise Price $1.48-$3.00 903,257 3.4 $ 2.29 848,969 $ 2.26 $3.01-$6.00 4,066,998 7.9 $ 3.90 1,844,977 $ 4.12 $6.01-$9.00 3,454,212 6.1 $ 7.20 3,210,448 $ 7.24 $9.01-$12.00 220,880 5.8 $ 9.83 220,880 $ 9.83 $12.01-$15.00 620,043 4.2 $ 12.96 620,043 $ 12.96 9,265,390 6.5 $ 5.72 6,745,317 $ 6.37
Schedule of stock options, activity	Stock option activity under the Company’s equity incentive plans during the year ended December 31, 2019 was as follows: Number of Shares Weighted-Average Exercise Price Balance, December 31, 2018 8,752,677 $ 6.35 Granted 2,596,468 3.39 Exercised (42,969 ) 2.62 Cancelled (2,040,786 ) 5.49 Balance, December 31, 2019 9,265,390 $ 5.72
Schedule of Share-based Compensation, Restricted Stock Units Award Activity	Restricted stock unit activity under the Company’s equity incentive plans during the year ended December 31, 2019 was as follows: Number of Shares Balance, December 31, 2018 1,688,017 Granted 1,491,771 Vested (1,003,218 ) Cancelled (106,634 ) Balance, December 31, 2019 2,069,936

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Lessee, Operating Lease, Liability, Maturity	As of December 31, 2019 , the maturities of the Company's operating lease liabilities were as follows: Year ending December 31, 2020 $ 3,891,000 2021 3,979,000 2022 4,052,000 2023 4,023,000 2024 3,001,000 Thereafter 12,951,000 Total remaining lease payments 31,897,000 Less: present value adjustment (9,412,236 ) Total operating lease liabilities 22,484,764 Less: current portion (2,074,842 ) Long-term operating lease liabilities $ 20,409,922 Weighted-average remaining lease term 8.2 years Weighted-average discount rate 8.4 %
Schedule of Annual Future Minimum Lease Payments Under Non-cancelable Operating Leases	As of December 31, 2018, prior to the adoption of Topic 842, annual future minimum lease payments under non-cancelable operating leases were as follows: Year ending December 31, 2019 $ 3,756,000 2020 3,891,000 2021 3,979,000 2022 4,052,000 2023 4,023,000 Thereafter 15,952,000 Total $ 35,653,000

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of components of income tax expense (benefit)	The components of the provision for income taxes are presented in the following table: Year Ended December 31, 2019 2018 2017 Current: Federal $ 4,000 $ — $ — State 2,000 — — Foreign — 2,170,000 — 6,000 2,170,000 — Deferred: Federal (263,000 ) — State — — — Foreign — — — (263,000 ) — — $ (257,000 ) $ 2,170,000 $ —
Schedule of effective income tax rate reconciliation	The reconciliation of income taxes attributable to continuing operations computed at the statutory tax rates to income tax expense (benefit), using a 21% statutory tax rate for December 31, 2019 and 2018 , and 35% statutory tax rate for December 31, 2017, is as follows: Year Ended December 31, 2019 2018 2017 Income (benefit) taxes at statutory rates $ (25,370,000 ) $ (19,908,000 ) $ (30,872,000 ) State income tax, net of federal benefit — (4,000 ) (4,000 ) Foreign income taxes — 2,170,000 — Change in valuation allowance 25,457,000 20,898,000 (20,965,000 ) Research and development tax credits (3,838,000 ) (3,170,000 ) (3,456,000 ) Change in fair value of warrants — (76,000 ) (282,000 ) Stock-based compensation 1,114,000 1,094,000 2,332,000 Uncertain tax positions 1,537,000 1,268,000 846,000 Expired NOLs and credits 616,000 2,176,000 454,000 Limited NOLs and credits (616,000 ) (2,176,000 ) (165,000 ) Change in tax rates 12,000 — 50,019,000 Other 831,000 (102,000 ) 2,093,000 $ (257,000 ) $ 2,170,000 $ —
Schedule of deferred tax assets and liabilities	Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2019 and 2018 are shown below: As of December 31, 2019 2018 Deferred tax assets: Capitalized research expense $ 6,300,000 $ 7,408,000 NOL carryforwards 110,788,000 89,399,000 Research and development and other tax credits 11,737,000 9,432,000 Deferred revenue 1,506,000 985,000 Deferred rent — 2,013,000 Stock-based compensation 3,255,000 3,408,000 Acquired intangibles 889,000 912,000 Derivative liability 1,852,000 — Interest expense 1,122,000 — Investment in affiliated entity 645,000 — Lease liability 4,722,000 — Other 2,413,000 2,693,000 145,229,000 116,250,000 Valuation allowance (137,159,000 ) (115,007,000 ) Total deferred tax assets 8,070,000 1,243,000 Deferred tax liabilities: Acquired intangibles (160,000 ) (142,000 ) Investment in affiliated entity — (4,000 ) Right of use asset (2,894,000 ) — Note discount (2,862,000 ) — Convertible note (1,381,000 ) — Fixed assets (805,000 ) (1,121,000 ) Net deferred tax liabilities $ (32,000 ) $ (24,000 )
Schedule of operating loss and tax credit carryforward expirations	Based upon statute, federal and state losses and credits are expected to expire as follows (in millions): Expiration Date: Federal NOLs State NOLs Federal R&D State R&D 2020 $ 1.6 $ — $ — $ — 2021 2.3 0.3 — — 2022 6.0 0.3 — — 2023 4.5 0.4 — — 2024 and thereafter 282.3 148.1 17.3 — Indefinite 186.6 — — 3.2 $ 483.3 $ 149.1 $ 17.3 $ 3.2
Schedule of unrecognized tax benefits rollforward	The following table summarizes the activity related to the Company's unrecognized tax benefits: Year ended December 31, 2019 2018 2017 Balance at beginning of the year $ 9,632,000 $ 8,313,000 $ 6,855,000 Increases related to current year tax positions 1,575,000 1,319,000 1,532,000 Increases (decreases) related to prior year tax positions (3,000 ) — (74,000 ) Balance at end of the year $ 11,204,000 $ 9,632,000 $ 8,313,000

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Schedule of quarterly financial information (unaudited)	The following is a summary of the quarterly results of operations of the Company for the years ended December 31, 2019 and 2018 (unaudited): Quarter Ended Quarter Ended Quarter Ended Quarter Ended December 31, September 30, June 30, March 31, Consolidated Statements of Operations: Revenues: Revenue under collaborative research and development arrangements $ 184,523 $ 617,427 $ 64,283 $ 2,770,712 Revenue under collaborative research and development arrangements with affiliated entities 55,665 53,014 71,390 55,579 Miscellaneous revenue, including from affiliated entities 39,300 196,422 — 3,614 Total revenues 279,488 866,863 135,673 2,829,905 Operating Expenses: Research and development 22,003,955 19,137,209 22,486,266 24,389,888 General and administrative 8,696,586 5,681,441 5,850,101 6,975,029 Total operating expenses 30,700,541 24,818,650 28,336,367 31,364,917 Loss from operations (30,421,053 ) (23,951,787 ) (28,200,694 ) (28,535,012 ) Interest income 587,679 637,438 755,330 625,535 Interest expense (2,668,837 ) (2,428,671 ) (2,194,783 ) (656,248 ) Change in fair value of derivative liability (4,315,105 ) 2,551,453 — — Loss on investment in affiliated entities (1,681,401 ) (485,841 ) (173,212 ) (750,103 ) Other income (expense), net 263,571 140,956 127,512 (35,839 ) Net loss before income tax benefit $ (38,235,146 ) $ (23,536,452 ) $ (29,685,847 ) $ (29,351,667 ) Income tax benefit 87,764 — 106,771 62,800 Net loss $ (38,147,382 ) $ (23,536,452 ) $ (29,579,076 ) $ (29,288,867 ) Net loss attributable to non-controlling interest 485,344 445,759 191,850 69,605 Net loss attributable to Inovio Pharmaceuticals, Inc. $ (37,662,038 ) $ (23,090,693 ) $ (29,387,226 ) $ (29,219,262 ) Net loss per share Basic $ (0.38 ) $ (0.23 ) $ (0.30 ) $ (0.30 ) Diluted $ (0.38 ) $ (0.25 ) $ (0.30 ) $ (0.30 ) Quarter Ended Quarter Ended Quarter Ended Quarter Ended December 31, September 30, June 30, March 31, Consolidated Statements of Operations: Revenues: Revenue under collaborative research and development arrangements $ 2,372,600 $ 1,813,287 $ 24,385,852 $ 1,289,046 Revenue under collaborative research and development arrangements with affiliated entity 56,207 184,990 60,319 148,008 Miscellaneous revenue 73,817 2,591 2,590 92,590 Total revenues 2,502,624 2,000,868 24,448,761 1,529,644 Operating Expenses: Research and development 26,365,647 21,851,858 22,462,620 24,577,751 General and administrative 5,636,141 6,791,693 7,189,310 9,698,015 Total operating expenses 32,001,788 28,643,551 29,651,930 34,275,766 Loss from operations (29,499,164 ) (26,642,683 ) (5,203,169 ) (32,746,122 ) Interest and other income, net (169,300 ) 380,987 396,681 312,523 Change in fair value of common stock warrants — 228,665 259,971 (127,841 ) Gain (loss) from investment in affiliated entities (3,293,741 ) 1,017,359 (2,092,608 ) 2,380,423 Net loss before provision for income taxes (32,962,205 ) (25,015,672 ) (6,639,125 ) (30,181,017 ) Provision for income taxes — — — (2,169,811 ) Net loss (32,962,205 ) (25,015,672 ) (6,639,125 ) (32,350,828 ) Net loss per share Basic $ (0.34 ) $ (0.27 ) $ (0.07 ) $ (0.36 ) Diluted $ (0.34 ) $ (0.27 ) $ (0.08 ) $ (0.36 )

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details)	1 Months Ended	2 Months Ended	3 Months Ended				12 Months Ended
	Jul. 31, 2019	Mar. 11, 2020USD ($)shares	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2019KRW (₩)	Dec. 26, 2019	Aug. 01, 2019	Mar. 01, 2019USD ($)	Jan. 01, 2019USD ($)
Property, Plant and Equipment [Line Items]
Net loss from operations			$ (37,662,038)	$ (23,090,693)	$ (29,387,226)	$ (29,219,262)	$ (119,359,219)	$ (96,967,830)	$ (88,205,772)
Working capital			62,200,000				62,200,000
Accumulated deficit			(739,785,655)				(739,785,655)	(620,426,436)
Proceeds from issuance of common stock							9,089,010	29,227,776	$ 94,347,922
Cash, cash equivalents, and short-term investments			89,500,000				89,500,000
Investments in affiliated entities			6,315,356				$ 6,315,356	9,405,913
Expected number of positions to be eliminated, percent	28.00%
Restructuring charges				$ 2,200,000
Number of operating segments | segment							1
Allowance for doubtful accounts			0				$ 0	0
Finite lived intangible assets, net			3,693,851				3,693,851	4,760,145
Deferred tax assets, valuation allowance			137,159,000				137,159,000	115,007,000
Operating right-of-use assets			13,783,009				13,783,009							$ 14,634,769
Total operating lease liabilities			22,484,764				$ 22,484,764
Minimum
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, useful life							3 years
Intangible asset, useful life							2 years
Maximum
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, useful life							5 years
Intangible asset, useful life							18 years
Accounting Standards Update 2016-02
Property, Plant and Equipment [Line Items]
Operating right-of-use assets														14,600,000
Total operating lease liabilities														24,200,000
Deferred rent credit														$ (9,600,000)
Sales Agreement
Property, Plant and Equipment [Line Items]
Proceeds from issuance of common stock							$ 9,100,000
6.50% Convertible Senior Notes Due 2024
Property, Plant and Equipment [Line Items]
Debt instrument, face amount			78,500,000				78,500,000						$ 78,500,000
Stated interest rate						6.50%							6.50%
August 2019 Convertible Bonds
Property, Plant and Equipment [Line Items]
Debt instrument, face amount			15,578,211				15,578,211
December 2019 Convertible Bonds
Property, Plant and Equipment [Line Items]
Debt instrument, face amount			4,067,644				4,067,644
Convertible Debt | 6.50% Convertible Senior Notes Due 2024
Property, Plant and Equipment [Line Items]
Proceeds from issuance of debt							75,700,000
Debt instrument, face amount			$ 78,500,000				$ 78,500,000						$ 78,500,000
Stated interest rate			6.50%				6.50%			6.50%
Convertible Debt | August 2019 Convertible Bonds
Property, Plant and Equipment [Line Items]
Proceeds from issuance of debt							$ 14,500,000
Debt instrument, face amount			$ 15,000,000				$ 15,000,000			₩ 18,000,000,000
Stated interest rate			1.00%				1.00%			1.00%		1.00%
Convertible Debt | December 2019 Convertible Bonds
Property, Plant and Equipment [Line Items]
Proceeds from issuance of debt							$ 4,000,000
Debt instrument, face amount			$ 4,100,000				$ 4,100,000			₩ 4,700,000,000
Stated interest rate			1.00%				1.00%			1.00%	1.00%
Geneos Therapeutics, Inc.
Property, Plant and Equipment [Line Items]
Non-controlling interest			39.00%				39.00%			39.00%
VGX Animal Health, Inc
Property, Plant and Equipment [Line Items]
Non-controlling interest			15.00%				15.00%			15.00%
Fair Value, Measurements, Recurring
Property, Plant and Equipment [Line Items]
Investments in affiliated entities			$ 6,315,356				$ 6,315,356	9,405,913
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Property, Plant and Equipment [Line Items]
Investments in affiliated entities			6,315,356				$ 6,315,356	9,405,913
Subsequent Event | Common stock | Sales Agreement
Property, Plant and Equipment [Line Items]
Proceeds from issuance of common stock		$ 208,200,000
Number of shares issued in transaction (in shares) | shares		43,148,952
Patents
Property, Plant and Equipment [Line Items]
Intangible asset, useful life							17 years
Finite lived intangible assets, net			$ 0				$ 0	$ 60,449

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Calculation of Net Loss Per Share (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator
Net loss attributable to Inovio Pharmaceuticals, Inc.	$ (37,662,038)	$ (23,090,693)	$ (29,387,226)	$ (29,219,262)					$ (119,359,219)	$ (96,967,830)	$ (88,205,772)
Adjustment for decrease in fair value of warrant liability									0	0	(806,819)
Numerator for use in diluted net loss per share									$ (119,359,219)	$ (96,967,830)	$ (89,012,591)
Denominator
Weighted average number of common shares outstanding (denominator for use in basic net loss per share) (shares)									98,717,999	92,539,997	81,777,493
Effect of dilutive potential common shares (shares)									0	0	140,529
Denominator for use in diluted loss per share (shares)									98,717,999	92,539,997	81,918,022
Net loss per share, diluted ($ per share)	$ (0.38)	$ (0.25)	$ (0.30)	$ (0.30)	$ (0.34)	$ (0.27)	$ (0.08)	$ (0.36)	$ (1.21)	$ (1.05)	$ (1.09)
Net loss per share, basic ($ per share)	$ (0.38)	$ (0.23)	$ (0.30)	$ (0.30)	$ (0.34)	$ (0.27)	$ (0.07)	$ (0.36)	$ (1.21)	$ (1.05)	$ (1.08)

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Antidilutive Securities Table (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	30,737,956	10,449,150	8,937,494
Options to purchase common stock
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	9,265,390	8,752,677	7,694,870
Restricted stock units
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	2,069,936	1,688,017	1,234,168
Convertible preferred stock
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	8,456	8,456	8,456
6.50% Convertible Senior Notes Due 2024 | Convertible Debt Securities
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	14,585,653	0	0
August 2019 Convertible Bonds | Convertible Debt Securities
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	3,799,071	0	0
December 2019 Convertible Bonds | Convertible Debt Securities
Summary of common shares that were excluded from the diluted net loss per share calculation because of their anti-dilutive effect
Total antidilutive securities (shares)	1,009,450	0	0

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Summary of Stock-Based Compensation Assumptions (Details) - Stock Options	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employees and Directors
Summary of assumptions used to estimate the fair value of stock options
Risk-free interest rate	2.42%	2.73%	2.20%
Expected volatility	70.00%	72.00%	73.00%
Expected life in years	6 years	6 years	6 years
Dividend yield	0.00%	0.00%	0.00%
Non Employee
Summary of assumptions used to estimate the fair value of stock options
Risk-free interest rate	2.45%	2.71%	2.42%
Expected volatility	88.00%	78.00%	99.00%
Expected life in years	10 years	9 years	9 years
Dividend yield	0.00%	0.00%	0.00%

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Impact of Recently Issued Accounting Standards - Impact of Adopting ASU 2016-02 (Details) - USD ($)	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred rent	$ 0		$ 1,065,387
Deferred rent, non-current portion	0		8,518,207
Operating right-of-use assets	13,783,009	$ 14,634,769
Operating lease liability	2,074,842	1,733,600	$ 0
Operating lease liability, net of current portion	$ 20,409,922	22,484,763
Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred rent		1,065,387
Deferred rent, non-current portion		8,518,207
Impact of Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred rent		(1,065,387)
Deferred rent, non-current portion		(8,518,207)
Operating right-of-use assets		14,634,769
Operating lease liability		1,733,600
Operating lease liability, net of current portion		$ 22,484,763

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 279,488	$ 866,863	$ 135,673	$ 2,829,905	$ 2,502,624	$ 2,000,868	$ 24,448,761	$ 1,529,644	$ 4,111,930	$ 30,481,897	$ 42,220,086
Revenue recognized from deferred revenue beginning balance									293,000	$ 1,300,000
AstraZeneca
Disaggregation of Revenue [Line Items]
Total revenues									3,200,000
Other Counterparty
Disaggregation of Revenue [Line Items]
Total revenues									$ 917,000

Collaborative Agreements (Detai

Collaborative Agreements (Details)	Apr. 11, 2018USD ($)	Dec. 29, 2017	Aug. 07, 2015product	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues							$ 279,488	$ 866,863	$ 135,673	$ 2,829,905	$ 2,502,624	$ 2,000,868	$ 24,448,761	$ 1,529,644	$ 4,111,930	$ 30,481,897	$ 42,220,086
Deferred grant funding							6,065,212				4,165,848				6,065,212	4,165,848
ApolloBio | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Territory expansion option period		3 years
Proceeds from collaborative agreement				$ 19,400,000
Upfront payment received				23,000,000											23,000,000
Advisory fees				960,000										$ 960,000
Additional revenue to be achieved															$ 20,000,000
Obligation period to pay royalties															10 years
Agreement period from effective date for termination															1 year
Agreement, number of days written notice before termination															90 days
AstraZeneca
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenues															$ 3,200,000
AstraZeneca | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received						$ 27,500,000											$ 27,500,000
Agreement anticipated development and regulatory event based payment receivable milestones															125,000,000
Agreement, anticipated commercial event based payment receivable milestones															115,000,000
Number of additional products | product			2
Agreement, milestone payment, revenue recognized					$ 2,000,000
Accounts receivable							200,000				$ 3,200,000				200,000	3,200,000
Coalition for Epidemic Preparedness Innovations | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront payment received															6,300,000	$ 4,300,000
Collaborative agreement, funding to be received	$ 56,000,000
Collaborative agreement, period to receive funding for research and development	5 years
Deferred grant funding							$ 5,000,000								$ 5,000,000
Foreign Tax Authority | ApolloBio | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative agreement, corporate income tax				2,200,000
Collaborative agreement, foreign non-income Taxes				$ 1,400,000

Short-term Investments - Narrat

Short-term Investments - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)investment	Dec. 31, 2018USD ($)
Investments, Debt and Equity Securities [Abstract]
Debt securities, available-for-sale, realized gain	$ 594	$ 20
Debt securities, available-for-sale, realized gain	$ 118	$ 1,300
Number of securities in a gross unrealized loss position | investment	4
Number of securities in a gross unrealized loss position for more than twelve months | investment	2
Unrealized loss	$ 11

Short-term Investments - Summar

Short-term Investments - Summary of Available-for-sale Securities (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Cost	$ 58,067,588
Gross Unrealized Gains	0
Gross Unrealized Losses	(528,736)
Fair Market Value	57,538,852
Mutual funds
Debt Securities, Available-for-sale [Line Items]
Cost	57,842,955	$ 66,599,219
Gross Unrealized Gains	0	754,709
Gross Unrealized Losses	(528,084)	(15,911)
Fair Market Value	57,314,871	$ 67,338,017
US corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Cost	224,633
Gross Unrealized Gains	0
Gross Unrealized Losses	(652)
Fair Market Value	$ 223,981
Maximum | US corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Contractual maturity	2 years

Fair Value Measurements Assets

Fair Value Measurements Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		$ 57,538,852
Investments in affiliated entities	$ 6,315,356	9,405,913
Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Derivative liability (Note 10)	7,100,000
Mutual funds
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities	67,338,017	57,314,871
Fair Value, Measurements, Recurring
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		223,981
Investments in affiliated entities	6,315,356	9,405,913
Assets, fair value	76,003,102	76,591,272
Derivative liability (Note 10)	8,819,023
Liabilities, fair value	8,819,023
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		0
Investments in affiliated entities	6,315,356	9,405,913
Assets, fair value	8,665,085	19,052,420
Derivative liability (Note 10)	0
Liabilities, fair value	0
Fair Value, Measurements, Recurring | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		223,981
Investments in affiliated entities	0	0
Assets, fair value	67,338,017	57,538,852
Derivative liability (Note 10)	0
Liabilities, fair value	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
US corporate debt securities		0
Investments in affiliated entities	0	0
Assets, fair value	0	0
Derivative liability (Note 10)	8,819,023
Liabilities, fair value	8,819,023
Fair Value, Measurements, Recurring | Money market funds
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents	2,349,729	9,646,507
Fair Value, Measurements, Recurring | Money market funds | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents	2,349,729	9,646,507
Fair Value, Measurements, Recurring | Money market funds | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents	0	0
Fair Value, Measurements, Recurring | Money market funds | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents	0	0
Fair Value, Measurements, Recurring | Mutual funds
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents	67,338,017	57,314,871
Fair Value, Measurements, Recurring | Mutual funds | Quoted Prices in Active Markets (Level 1)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents	0	0
Fair Value, Measurements, Recurring | Mutual funds | Significant Other Unobservable Inputs (Level 2)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents	67,338,017	57,314,871
Fair Value, Measurements, Recurring | Mutual funds | Significant Unobservable Inputs (Level 3)
Financial assets and liabilities that are measured at fair value on recurring basis
Cash and cash equivalents	$ 0	$ 0

Fair Value Measurements Narrati

Fair Value Measurements Narrative (Details) - Fair Value, Inputs, Level 1 $ in Millions	Dec. 31, 2019USD ($)shares
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Number of shares held in an affiliated entity (in shares)	1,644,155
Derivative liability | $	$ 7.1
Common stock
Marketable Securities and Fair Value Measurements (Textual) [Abstract]
Number of shares owned (shares)	395,758

Fair Value Measurements Marketa

Fair Value Measurements Marketable Securities and Fair Value Measurements - Fair Value of the Company's Derivative Liability (Details)	12 Months Ended
	Dec. 31, 2019USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of year	$ 0
Initial fair value upon issuance of the Bonds	7,055,371
Change in fair value	1,763,652
Balance at end of year	$ 8,819,000

Major Customers and Concentra_3

Major Customers and Concentration of Credit Risk (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Total revenues	$ 279,488	$ 866,863	$ 135,673	$ 2,829,905	$ 2,502,624	$ 2,000,868	$ 24,448,761	$ 1,529,644	$ 4,111,930	$ 30,481,897	$ 42,220,086
Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage									100.00%	100.00%	100.00%
ApolloBio
Concentration Risk [Line Items]
Total revenues									$ 0	$ 23,000,000	$ 0
ApolloBio | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage									0.00%	75.00%	0.00%
AstraZeneca
Concentration Risk [Line Items]
Total revenues									$ 3,194,877	$ 6,850,424	$ 22,269,773
Accounts receivable	161,000				$ 3,200,000				$ 161,000	$ 3,200,000
AstraZeneca | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage									78.00%	23.00%	53.00%
AstraZeneca | Accounts Receivable | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage									23.00%	98.00%
DARPA
Concentration Risk [Line Items]
Total revenues									$ 0	$ 0	$ 9,983,927
DARPA | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage									0.00%	0.00%	24.00%
Roche
Concentration Risk [Line Items]
Total revenues									$ 0	$ 0	$ 6,107,254
Roche | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage									0.00%	0.00%	14.00%
All other, including affiliated entities
Concentration Risk [Line Items]
Total revenues									$ 917,053	$ 631,473	$ 3,859,132
All other, including affiliated entities | Revenue | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage									22.00%	2.00%	9.00%
MCDC
Concentration Risk [Line Items]
Accounts receivable	$ 469,000								$ 469,000
MCDC | Accounts Receivable | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk, percentage									67.00%

Fixed Assets (Details)

Fixed Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Cost	$ 25,939,475	$ 25,948,933
Accumulated Depreciation and Amortization	(13,166,458)	(9,999,919)
Net Book Value	12,773,017	15,949,014
Depreciation	3,598,388	3,747,183	$ 1,850,376
Property, plant and equipment disposed of	6,000
Accumulated depreciation written off due to disposal of property plant and equipment	432,000
Leasehold improvements
Property, Plant and Equipment [Line Items]
Cost	15,007,935	14,909,341
Accumulated Depreciation and Amortization	(4,996,777)	(3,464,444)
Net Book Value	10,011,158	11,444,897
Laboratory equipment
Property, Plant and Equipment [Line Items]
Cost	4,102,467	4,031,965
Accumulated Depreciation and Amortization	(3,229,357)	(2,425,854)
Net Book Value	873,110	1,606,111
Office furniture and fixtures
Property, Plant and Equipment [Line Items]
Cost	3,048,053	3,198,803
Accumulated Depreciation and Amortization	(1,944,293)	(1,767,653)
Net Book Value	1,103,760	1,431,150
Computer equipment and other
Property, Plant and Equipment [Line Items]
Cost	3,781,020	3,808,824
Accumulated Depreciation and Amortization	(2,996,031)	(2,341,968)
Net Book Value	$ 784,989	$ 1,466,856

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Summary of Goodwill and Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Apr. 30, 2016	Jun. 30, 2009	Jan. 31, 2005
Indefinite lived:
Goodwill	$ 10,513,371	$ 10,513,371
Definite lived:
Intangible assets, Gross	24,717,873	24,717,873
Intangible assets, Accumulated Amortization	(21,024,022)	(19,957,728)
Intangible assets, net book value	3,693,851	4,760,145
Total goodwill and intangible assets, Gross	35,231,244	35,231,244
Total goodwill and intangible assets, Net Book Value	$ 14,207,222	15,273,516
Inovio AS
Indefinite lived:
Goodwill					$ 3,900,000
VGX
Indefinite lived:
Goodwill				$ 6,200,000
Bioject
Indefinite lived:
Goodwill			$ 400,000
Weighted Average
Schedule of intangible assets by major asset class
Intangible asset, useful life	11 years
Patents
Schedule of intangible assets by major asset class
Intangible asset, useful life	17 years
Definite lived:
Intangible assets, Gross	$ 5,802,528	5,802,528
Intangible assets, Accumulated Amortization	(5,802,528)	(5,742,079)
Intangible assets, net book value	$ 0	60,449
Patents | Weighted Average
Schedule of intangible assets by major asset class
Intangible asset, useful life	10 years
Licenses
Definite lived:
Intangible assets, Gross	$ 1,323,761	1,323,761
Intangible assets, Accumulated Amortization	(1,248,104)	(1,219,357)
Intangible assets, net book value	$ 75,657	104,404
Licenses | Weighted Average
Schedule of intangible assets by major asset class
Intangible asset, useful life	10 years
CELLECTRA
Definite lived:
Intangible assets, Gross	$ 8,106,270	8,106,270
Intangible assets, Accumulated Amortization	(8,106,270)	(7,679,190)
Intangible assets, net book value	$ 0	427,080
CELLECTRA | Weighted Average
Schedule of intangible assets by major asset class
Intangible asset, useful life	8 years
GHRH
Definite lived:
Intangible assets, Gross	$ 335,314	335,314
Intangible assets, Accumulated Amortization	(335,314)	(303,630)
Intangible assets, net book value	$ 0	31,684
GHRH | Weighted Average
Schedule of intangible assets by major asset class
Intangible asset, useful life	11 years
Bioject
Definite lived:
Intangible assets, Gross	$ 5,100,000	5,100,000
Intangible assets, Accumulated Amortization	(2,175,556)	(1,882,222)
Intangible assets, net book value	$ 2,924,444	3,217,778
Bioject | Weighted Average
Schedule of intangible assets by major asset class
Intangible asset, useful life	12 years
Other
Definite lived:
Intangible assets, Gross	$ 4,050,000	4,050,000
Intangible assets, Accumulated Amortization	(3,356,250)	(3,131,250)
Intangible assets, net book value	$ 693,750	$ 918,750
Other | Weighted Average
Schedule of intangible assets by major asset class
Intangible asset, useful life	18 years

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Schedule of Amortization Expense (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets (Textual) [Abstract]
2020	$ 547,081
2021	520,414
2022	492,818
2023	275,760
2024	253,333
Thereafter	1,604,445
Intangible assets, net book value	$ 3,693,851	$ 4,760,145

Goodwill and Intangible Asset_4

Goodwill and Intangible Assets - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 1,066,294	$ 1,249,584	$ 1,618,665
Impairment	$ 0	$ 0	$ 0

Convertible Debt Narrative (Det

Convertible Debt Narrative (Details)	Dec. 26, 2019USD ($)$ / shares	Aug. 01, 2019USD ($)$ / shares	Mar. 01, 2019USD ($)	Dec. 31, 2019USD ($)$ / shares	Sep. 30, 2019USD ($)	Jun. 30, 2019USD ($)	Mar. 31, 2019USD ($)	Dec. 31, 2019USD ($)day$ / shares	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2019KRW (₩)
Debt Instrument [Line Items]
Debt instrument, convertible, conversion price ($ per share) | $ / shares				$ 5.38				$ 5.38
Debt instrument, convertible, threshold percentage of stock price trigger								130.00%
Debt instrument, convertible, threshold trading days | day								20
Debt instrument, convertible, threshold consecutive trading days | day								30
Debt instrument, redemption price, percentage								100.00%
Long-term debt, fair value				$ 62,200,000				$ 62,200,000
Debt issuance costs, net				2,800,000				2,800,000
Debt instrument, unamortized discount				$ 18,600,000				$ 18,600,000
Debt instrument, interest rate, effective percentage				13.10%				13.10%			13.10%
Interest expense				$ 2,668,837	$ 2,428,671	$ 2,194,783	$ 656,248	$ 7,948,539	$ 0	$ 25,933
Change in fair value of derivative liability				(4,315,105)	$ 2,551,453	$ 0	$ 0	(1,763,652)	$ 0	$ 0
6.50% Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Debt instrument, face amount			$ 78,500,000	78,500,000				78,500,000
Stated interest rate			6.50%				6.50%
Proceeds from issuance of debt			$ 75,700,000
Debt issuance costs, net				1,938,206				1,938,206
Debt instrument, unamortized discount				14,082,302				14,082,302
August 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, face amount				15,578,211				15,578,211
Debt issuance costs, net				255,185				255,185
Debt instrument, unamortized discount				6,764,346				6,764,346
December 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, face amount				4,067,644				4,067,644
Debt issuance costs, net				50,000				50,000
Interest expense								0
Convertible Debt | 6.50% Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Debt instrument, face amount			$ 78,500,000	$ 78,500,000				$ 78,500,000
Stated interest rate				6.50%				6.50%			6.50%
Debt instrument, convertible, conversion ratio			0.1858045
Interest expense								$ 7,000,000
Interest expense, debt								4,400,000
Convertible Debt | August 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, face amount				$ 15,000,000				$ 15,000,000			₩ 18,000,000,000
Stated interest rate		1.00%		1.00%				1.00%			1.00%
Proceeds from issuance of debt		$ 14,500,000
Debt instrument, unamortized discount		$ 7,300,000
Debt instrument, interest rate, effective percentage				29.40%				29.40%			29.40%
Interest expense								$ 982,000
Interest expense, debt								$ 65,000
Debt instrument, convertible, internal rate of return		6.00%		6.00%				6.00%			6.00%
Debt instrument, convertible, required bondholder approval, percentage		25.00%
Debt instrument, convertible, carrying amount of equity component		$ 7,100,000
Derivative liability (Note 10)				$ 8,800,000				$ 8,800,000
Change in fair value of derivative liability								1,800,000
Convertible Debt | December 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, face amount				$ 4,100,000				$ 4,100,000			₩ 4,700,000,000
Stated interest rate	1.00%			1.00%				1.00%			1.00%
Proceeds from issuance of debt	$ 4,000,000
Debt instrument, interest rate, effective percentage				6.20%				6.20%			6.20%
Debt instrument, convertible, internal rate of return	6.00%			6.00%				6.00%			6.00%
Debt instrument, convertible, required bondholder approval, percentage	25.00%
Initial Conversion Price | Convertible Debt | August 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio		0.0002110595
Debt instrument, convertible, conversion price ($ per share) | $ / shares		$ 4
Initial Conversion Price | Convertible Debt | December 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio	0.0002147766
Debt instrument, convertible, conversion price ($ per share) | $ / shares	$ 4
After January 2, 2020 Conversion Price | Convertible Debt | August 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio		0.0003517658
Event Of Default | Convertible Debt | August 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, convertible, internal rate of return		8.00%
After July 2, 2020 Conversion Price | Convertible Debt | December 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, convertible, conversion ratio	0.0003579611
Maximum | After January 2, 2020 Conversion Price | Convertible Debt | August 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, convertible, conversion price ($ per share) | $ / shares		$ 2.40
Maximum | After July 2, 2020 Conversion Price | Convertible Debt | December 2019 Convertible Bonds
Debt Instrument [Line Items]
Debt instrument, convertible, conversion price ($ per share) | $ / shares	$ 2.40

Convertible Debt - Balance Of C

Convertible Debt - Balance Of Convertible Debt (Details) - USD ($)	Dec. 31, 2019	Mar. 01, 2019
Debt Instrument [Line Items]
Unamortized debt discount on the liability component	$ (18,600,000)
Unamortized debt issuance cost	(2,800,000)
6.50% Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Principal amount	78,500,000	$ 78,500,000
Unamortized debt discount on the liability component	(14,082,302)
Unamortized debt issuance cost	(1,938,206)
Accrued interest	1,700,833
Total	64,180,325
August 2019 Convertible Bonds
Debt Instrument [Line Items]
Principal amount	15,578,211
Unamortized debt discount on the liability component	(6,764,346)
Unamortized debt issuance cost	(255,185)
Accretion of premium associated with the bonds	227,322
Accrued interest	38,946
Total	8,824,948
December 2019 Convertible Bonds
Debt Instrument [Line Items]
Principal amount	4,067,644
Unamortized debt issuance cost	(50,000)
Accretion of premium associated with the bonds	0
Accrued interest	0
Total	$ 4,017,644

Convertible Debt - Schedule of

Convertible Debt - Schedule of Maturities (Details) - USD ($)	Dec. 31, 2019	Dec. 26, 2019	Aug. 01, 2019	Mar. 31, 2019	Mar. 01, 2019
6.50% Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
Total	$ 64,180,325
Stated interest rate				6.50%	6.50%
August 2019 Convertible Bonds
Debt Instrument [Line Items]
Total	8,824,948
December 2019 Convertible Bonds
Debt Instrument [Line Items]
Total	4,017,644
Convertible Debt
Debt Instrument [Line Items]
2020	5,290,000
2021	5,300,000
2022	5,300,000
2023	5,300,000
2024	106,308,000
Total	127,498,000
Convertible Debt | 6.50% Convertible Senior Notes Due 2024
Debt Instrument [Line Items]
2020	5,103,000
2021	5,103,000
2022	5,103,000
2023	5,103,000
2024	81,051,000
Total	$ 101,463,000
Stated interest rate	6.50%
Convertible Debt | August 2019 Convertible Bonds
Debt Instrument [Line Items]
2020	$ 156,000
2021	156,000
2022	156,000
2023	156,000
2024	20,021,000
Total	$ 20,645,000
Stated interest rate	1.00%		1.00%
Debt instrument, convertible, internal rate of return	6.00%		6.00%
Convertible Debt | December 2019 Convertible Bonds
Debt Instrument [Line Items]
2020	$ 31,000
2021	41,000
2022	41,000
2023	41,000
2024	5,236,000
Total	$ 5,390,000
Stated interest rate	1.00%	1.00%
Debt instrument, convertible, internal rate of return	6.00%	6.00%

Accounts Payable and Accrued _3

Accounts Payable and Accrued Expenses (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Trade accounts payable	$ 6,919,081	$ 10,043,816
Accrued compensation	8,967,897	9,466,821
Accrued subcontract costs	273,508	83,812
Other accrued expenses	2,076,772	3,540,284
Accounts payable and accrued liabilities	$ 18,237,258	$ 23,134,733

Stockholders' Equity Summary of

Stockholders' Equity Summary of Preferred Stock (Details) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Summary of common and preferred stock authorized, issued and outstanding
Preferred Stock, par value ($ per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (shares)	10,000,000	10,000,000
Preferred stock, shares issued (shares)	23	23
Preferred stock, shares outstanding (shares)	23	23
Series C Preferred Stock
Summary of common and preferred stock authorized, issued and outstanding
Preferred Stock, par value ($ per share)	$ 0.001
Preferred stock, shares authorized (shares)	1,091
Preferred stock, shares issued (shares)	1,091
Preferred stock, shares outstanding (shares)	23	23

Stockholders' Equity Narrative

Stockholders' Equity Narrative (Details)	Mar. 09, 2020USD ($)	Feb. 07, 2020USD ($)	May 31, 2018USD ($)	Jun. 05, 2018USD ($)$ / sharesshares	Dec. 31, 2019USD ($)dayvote$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares	Dec. 31, 2017USD ($)$ / sharesshares	Jun. 05, 2018USD ($)$ / sharesshares	Mar. 11, 2020$ / shares	Jan. 01, 2020shares	May 13, 2016shares
Class of Stock [Line Items]
Preferred stock, par value ($ per share) | $ / shares					$ 0.001	$ 0.001
Convertible preferred stock, shares issued upon conversion, conversion price ($ per share) | $ / shares					27.20
Daily market price triggering mandatory conversion ($ per share) | $ / shares					$ 72
Number of trading days | day					20
Number of consecutive trading days | day					30
Warrants exercised in period (shares) | shares						284,091
Proceeds from warrant exercises						$ 902,000
Number of warrants (shares) | shares					0	0
Share-based compensation					$ 10,901,320	$ 10,654,622	$ 13,070,962
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized					$ 3,400,000	$ 5,200,000
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized, period for recognition					1 year 7 months 31 days	1 year 8 months 12 days
Number of options outstanding to purchase common stock (shares) | shares					9,265,390	8,752,677
Aggregate intrinsic value of options outstanding					$ 918,000
Aggregate intrinsic value for options exercisable					$ 881,000
Options exercisable, remaining contractual term					5 years 8 months
Number of options expected to vest (shares) | shares					9,265,390
Options, expirations in period, weighted average exercise price ($ per share) | $ / shares					$ 6.27	$ 5.17	$ 9.67
Options, expirations in period (shares) | shares					324,502	119,091	200,501
Options, grants in period, weighted average grant date fair value ($ per share) | $ / shares					$ 2.19	$ 2.86	$ 4.33
Proceeds from stock options exercised					$ 100,000	$ 1,500,000	$ 2,300,000
Options, exercises in period, aggregate intrinsic value					25,000	910,000	519,000
Employee
Class of Stock [Line Items]
Share-based compensation					9,800,000	10,200,000	12,900,000
Research and Development Expense
Class of Stock [Line Items]
Share-based compensation					5,900,000	5,900,000	5,800,000
General and Administrative Expense
Class of Stock [Line Items]
Share-based compensation					3,900,000	4,300,000	7,100,000
Non Employee
Class of Stock [Line Items]
Allocated share-based compensation expense					$ 970,000	302,000	$ 201,000
Number of options outstanding to purchase common stock (shares) | shares					952,500
Restricted Stock Units (RSUs)
Class of Stock [Line Items]
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized					$ 4,300,000	$ 5,100,000
Employee service share-based compensation, nonvested awards, total compensation cost not yet recognized, period for recognition					1 year 6 months 31 days	1 year 8 months
Aggregate intrinsic value of unvested					$ 6,800,000
Aggregate intrinsic value of vested					$ 3,500,000
RSU's expected to vest (shares) | shares					2,069,936
Weighted average grant date fair value ($ per share) | $ / shares					$ 3.09	$ 4.31	$ 6.66
Minimum
Class of Stock [Line Items]
Average daily trading volume triggering mandatory conversion (shares) | shares					6,250
Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock, redemption price ($ per share) | $ / shares					$ 10,000
Preferred stock, par value ($ per share) | $ / shares					$ 0.001
Number of votes per share | vote					368
Convertible preferred stock, shares issued upon conversion (shares) | shares					8,456
Notice period for mandatory conversion of preferred stock					30 days
Common stock | Sales Agreement
Class of Stock [Line Items]
Authorized amount			$ 100,000,000
Agent fee			3.00%		3.00%
Stock sale agreement, aggregate number of shares issued (shares) | shares					3,340,678
Sale of stock, price per share ($ per share) | $ / shares					$ 2.78
Stock sale agreement, aggregate proceeds from issuance of stock					$ 9,100,000
Stock sales agreement, remaining authorized sales amount					$ 62,800,000
Common stock | ATM Sales Agreement
Class of Stock [Line Items]
Stock sale agreement, aggregate number of shares issued (shares) | shares				314,950			2,937,406	3,911,104
Sale of stock, price per share ($ per share) | $ / shares				$ 5.07			$ 8.41	$ 5.07
Stock sale agreement, aggregate proceeds from issuance of stock				$ 1,600,000			$ 24,200,000	$ 32,100,000
2016 Incentive Plan
Class of Stock [Line Items]
Reserved number of shares under the Incentive Plan (shares) | shares					16,000,000						16,000,000
Number of potential shares authorized for issuance under a share-based compensation plan (shares) | shares											2,000,000
Number of shares available for grants under the Incentive Plan (shares) | shares					8,214,032
Number of shares of vested restricted stock outstanding under the plan (shares) | shares					2,069,936
Number of common stock shares outstanding under the Incentive Plan (shares) | shares					4,497,736
Vesting period of incentive plan					3 years
Contractual year term of incentive plan					10 years
2007 Incentive Plan
Class of Stock [Line Items]
Number of common stock shares outstanding under the Incentive Plan (shares) | shares					4,767,654
Vesting period of incentive plan					3 years
Contractual year term of incentive plan					10 years
Subsequent Event | Common stock | Sales Agreement
Class of Stock [Line Items]
Authorized amount	$ 250,000,000	$ 200,000,000
Sale of stock, price per share ($ per share) | $ / shares									$ 4.92
Subsequent Event | 2016 Incentive Plan
Class of Stock [Line Items]
Increase in number of shares authorized (shares) | shares										2,000,000

Stockholders' Equity Summary _2

Stockholders' Equity Summary of Stock Options Outstanding (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Options outstanding (shares) | shares	9,265,390
Weighted-Average Remaining Contractual Life (in Years)	6 years 5 months 31 days
Weighted average exercise price ($ per share)	$ 5.72
Options exercisable (shares) | shares	6,745,317
Weighted-average exercise price ($ per share)	$ 6.37
$1.48-$3.00
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower range limit ($ per share)	1.48
Exercise price, upper range limit ($ per share)	$ 3
Options outstanding (shares) | shares	903,257
Weighted-Average Remaining Contractual Life (in Years)	3 years 4 months 31 days
Weighted average exercise price ($ per share)	$ 2.29
Options exercisable (shares) | shares	848,969
Weighted-average exercise price ($ per share)	$ 2.26
$3.01-$6.00
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower range limit ($ per share)	3.01
Exercise price, upper range limit ($ per share)	$ 6
Options outstanding (shares) | shares	4,066,998
Weighted-Average Remaining Contractual Life (in Years)	7 years 10 months 30 days
Weighted average exercise price ($ per share)	$ 3.90
Options exercisable (shares) | shares	1,844,977
Weighted-average exercise price ($ per share)	$ 4.12
$6.01-$9.00
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower range limit ($ per share)	6.01
Exercise price, upper range limit ($ per share)	$ 9
Options outstanding (shares) | shares	3,454,212
Weighted-Average Remaining Contractual Life (in Years)	6 years 31 days
Weighted average exercise price ($ per share)	$ 7.20
Options exercisable (shares) | shares	3,210,448
Weighted-average exercise price ($ per share)	$ 7.24
$9.01-$12.00
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower range limit ($ per share)	9.01
Exercise price, upper range limit ($ per share)	$ 12
Options outstanding (shares) | shares	220,880
Weighted-Average Remaining Contractual Life (in Years)	5 years 9 months 30 days
Weighted average exercise price ($ per share)	$ 9.83
Options exercisable (shares) | shares	220,880
Weighted-average exercise price ($ per share)	$ 9.83
$12.01-$15.00
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price, lower range limit ($ per share)	12.01
Exercise price, upper range limit ($ per share)	$ 15
Options outstanding (shares) | shares	620,043
Weighted-Average Remaining Contractual Life (in Years)	4 years 2 months 28 days
Weighted average exercise price ($ per share)	$ 12.96
Options exercisable (shares) | shares	620,043
Weighted-average exercise price ($ per share)	$ 12.96

Stockholders' Equity Summary _3

Stockholders' Equity Summary of Stock Option Activity Under Equity Incentive Plan (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Number of Shares
Beginning Balance (shares) | shares	8,752,677
Granted (shares) | shares	2,596,468
Exercised (shares) | shares	(42,969)
Cancelled (shares) | shares	(2,040,786)
Ending Balance (shares) | shares	9,265,390
Weighted-Average Exercise Price
Beginning Balance ($ per share) | $ / shares	$ 6.35
Granted ($ per share) | $ / shares	3.39
Exercised ($ per share) | $ / shares	2.62
Cancelled ($ per share) | $ / shares	5.49
Ending Balance ($ per share) | $ / shares	$ 5.72

Stockholders' Equity Summary _4

Stockholders' Equity Summary of RSU Activity Under Equity Incentive Plan (Details) - Restricted stock units	12 Months Ended
	Dec. 31, 2019shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Beginning balance (shares)	1,688,017
Granted (shares)	1,491,771
Vested (shares)	(1,003,218)
Cancelled (shares)	(106,634)
Ending balance (shares)	2,069,936

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019ft²lease	Dec. 31, 2019USD ($)ft²	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Mar. 31, 2019
Operating Leased Assets [Line Items]
Lessee, operating lease, area of land under lease	13,500
Weighted-average remaining lease term	8 years 2 months	8 years 2 months
Lease, cost | $		$ 3.2	$ 3.4	$ 2.5
Number of lease agreements entered into | lease	2
Minimum
Operating Leased Assets [Line Items]
Weighted-average remaining lease term					3 years 10 months 31 days
Maximum
Operating Leased Assets [Line Items]
Weighted-average remaining lease term					9 years 10 months 19 days
San Diego, California
Operating Leased Assets [Line Items]
Lessee, operating lease, area of land under lease		82,200
Plymouth Meeting, Pennsylvania
Operating Leased Assets [Line Items]
Lessee, operating lease, area of land under lease		57,360

Leases - Summary of Maturities

Leases - Summary of Maturities of Operating Lease Payments (Details) - USD ($)	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Leases [Abstract]
2020	$ 3,891,000
2021	3,979,000
2022	4,052,000
2023	4,023,000
2024	3,001,000
Thereafter	12,951,000
Total remaining lease payments	31,897,000
Less: present value adjustment	(9,412,236)
Total operating lease liabilities	22,484,764
Less: current portion	(2,074,842)	$ (1,733,600)	$ 0
Long-term operating lease liabilities	$ 20,409,922	$ 22,484,763
Weighted-average remaining lease term	8 years 2 months
Weighted-average discount rate	8.40%

Leases - Summary of Future Mini

Leases - Summary of Future Minimum Lease Payments Before Adoption of Topic 842 (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
2019	$ 3,756
2020	3,891
2021	3,979
2022	4,052
2023	4,023
Thereafter	15,952
Total	$ 35,653

Investments in Affiliated Ent_2

Investments in Affiliated Entities (Details) - shares	Dec. 31, 2019	Dec. 31, 2018
GeneOne Life Sciences
Related Party Transaction [Line Items]
Number of shares owned (shares)	1,644,155
Percentage of ownership	7.50%	7.80%
GeneOne Life Sciences | Common stock
Related Party Transaction [Line Items]
Number of shares owned (shares)	1,644,155	1,644,155
Plumbline Life Sciences
Related Party Transaction [Line Items]
Percentage of ownership	15.00%	15.10%
Plumbline Life Sciences | Common stock
Related Party Transaction [Line Items]
Number of shares owned (shares)	395,758	395,758

Income Taxes Summary of the Pro

Income Taxes Summary of the Provision for Income Taxes (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal									$ 4,000	$ 0	$ 0
State									2,000	0	0
Foreign									0	2,170,000	0
Current income tax expense (benefit)									6,000	2,170,000	0
Deferred:
Federal									(263,000)	0
State									0	0	0
Foreign									0	0	0
Deferred income tax expense (benefit)									(263,000)	0	0
Income tax expense (benefit)	$ (87,764)	$ 0	$ (106,771)	$ (62,800)	$ 0	$ 0	$ 0	$ 2,169,811	$ (257,335)	$ 2,169,811	$ 0

Income Taxes Reconciliation of

Income Taxes Reconciliation of Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Income (benefit) taxes at statutory rates	$ (25,370)	$ (19,908)	$ (30,872)
State income tax, net of federal benefit	0	(4)	(4)
Foreign income taxes	0	2,170	0
Change in valuation allowance	25,457	20,898	(20,965)
Research and development tax credits	(3,838)	(3,170)	(3,456)
Change in fair value of warrants	0	(76)	(282)
Stock-based compensation	1,114	1,094	2,332
Uncertain tax positions	1,537	1,268	846
Expired NOLs and credits	616	2,176	454
Limited NOLs and credits	(616)	(2,176)	(165)
Change in tax rates	12	0	50,019
Other	831	(102)	2,093
Income tax expense (benefit)	$ (257)	$ 2,170	$ 0

Income Taxes Narrative (Details

Income Taxes Narrative (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Income tax expense (benefit)	$ (87,764)	$ 0	$ (106,771)	$ (62,800)	$ 0	$ 0	$ 0	$ 2,169,811	$ (257,335)	$ 2,169,811	$ 0
Tax benefits expired	10,600,000								10,600,000
Unrecognized tax benefits that would impact effective tax rate	9,900,000				$ 8,300,000				9,900,000	$ 8,300,000	$ 7,100,000
Federal
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards that will expire due to IRC Section 382 limitations	483,300,000								483,300,000
Net operating loss carryforwards	186,600,000								186,600,000
State
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	149,100,000								149,100,000
California
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards that will expire due to IRC Section 382 limitations	68,600,000								68,600,000
Pennsylvania
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards that will expire due to IRC Section 382 limitations	80,500,000								80,500,000
Research Tax Credit Carryforward | Federal
Operating Loss Carryforwards [Line Items]
Tax credit carryforward amount	17,300,000								17,300,000
Research Tax Credit Carryforward | State
Operating Loss Carryforwards [Line Items]
Tax credit carryforward amount	$ 3,200,000								$ 3,200,000

Income Taxes Significant Compon

Income Taxes Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Capitalized research expense	$ 6,300	$ 7,408
NOL carryforwards	110,788	89,399
Research and development and other tax credits	11,737	9,432
Deferred revenue	1,506	985
Deferred rent	0	2,013
Stock-based compensation	3,255	3,408
Acquired intangibles	889	912
Derivative liability	1,852	0
Interest expense	1,122	0
Investment in affiliated entity	645	0
Lease liability	4,722	0
Other	2,413	2,693
Deferred tax assets, gross	145,229	116,250
Valuation allowance	(137,159)	(115,007)
Total deferred tax assets	8,070	1,243
Deferred tax liabilities:
Acquired intangibles	(160)	(142)
Investment in affiliated entity	0	(4)
Right of use asset	(2,894)	0
Note discount	(2,862)	0
Convertible note	(1,381)	0
Fixed assets	(805)	(1,121)
Net deferred tax liabilities	$ (32)	$ (24)

Income Taxes Expected Expiratio

Income Taxes Expected Expirations of Federal and State Losses and Credits (Details) $ in Millions	Dec. 31, 2019USD ($)
Federal
Expirations of Operating Loss Carryforwards, Components [Abstract]
2020	$ 1.6
2021	2.3
2022	6
2023	4.5
2024	282.3
Indefinite	186.6
Total	483.3
State
Expirations of Operating Loss Carryforwards, Components [Abstract]
2020	0
2021	0.3
2022	0.3
2023	0.4
2024	148.1
Indefinite	0
Total	149.1
Research Tax Credit Carryforward | Federal
Expirations of Tax Credit Carryforwards [Abstract]
2020	0
2021	0
2022	0
2023	0
2024	17.3
Indefinite	0
Total	17.3
Research Tax Credit Carryforward | State
Expirations of Tax Credit Carryforwards [Abstract]
2020	0
2021	0
2022	0
2023	0
2024	0
Indefinite	3.2
Total	$ 3.2

Income Taxes Unrecognized Tax B

Income Taxes Unrecognized Tax Benefits Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of the year	$ 9,632	$ 8,313	$ 6,855
Increases related to current year tax positions	1,575	1,319	1,532
Increases (decreases) related to prior year tax positions	(3)	0	(74)
Balance at end of the year	$ 11,204	$ 9,632	$ 8,313

401(k) Plan (Details)

401(k) Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Employer matching contribution, percent	50.00%
Maximum annual contribution per employee, percent	6.00%
Company's contribution to 401(k) plan	$ 1,200	$ 1,200	$ 822

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	1 Months Ended					12 Months Ended
	Dec. 31, 2017	Nov. 30, 2016	Mar. 31, 2016	Jan. 31, 2016	May 31, 2015	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2013	Dec. 31, 2010
Related Party Transaction [Line Items]
Full payment						$ 0	$ 0	$ 1,000,000
Long-term other assets						$ 2,672,024	2,669,998
GeneOne (affiliated entity)
Related Party Transaction [Line Items]
Number of shares owned (shares)						1,644,155
Payment received for license granted										$ 3,000,000
Term									20 years
Ownership target				35.00%	35.00%
Full payment	$ 1,000,000
Revenue from related parties						$ 127,000	342,000	551,000
Operating expenses related to affiliated entity						2,500,000	7,000,000	$ 2,300,000
Accounts payable/accrued liability						511,000	372,000
Long-term other assets						284,000	381,000
Accounts receivable						$ 128,000	0
PLS (affiliated entity)
Related Party Transaction [Line Items]
Number of shares owned (shares)						395,758
Revenue from related parties						$ 111,000	107,000
Accounts receivable						589,000	478,000
The Wistar Institute
Related Party Transaction [Line Items]
Term			5 years
Operating expenses related to affiliated entity						1,500,000	1,800,000
Accounts receivable						616,000	258,000
Expenses to reimburse			$ 3,100,000
Proceeds from sub-grant		$ 6,100,000
Grant proceeds received						2,200,000	3,300,000
Due to related parties						219,000	$ 554,000
Deferred grant funding from affiliate						$ 843,000

Quarterly Financial Informati_3

Quarterly Financial Information (Unaudited) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 279,488	$ 866,863	$ 135,673	$ 2,829,905	$ 2,502,624	$ 2,000,868	$ 24,448,761	$ 1,529,644	$ 4,111,930	$ 30,481,897	$ 42,220,086
Research and development	22,003,955	19,137,209	22,486,266	24,389,888	26,365,647	21,851,858	22,462,620	24,577,751	88,017,319	95,257,876	98,572,618
General and administrative	8,696,586	5,681,441	5,850,101	6,975,029	5,636,141	6,791,693	7,189,310	9,698,015	27,203,156	29,315,159	28,290,369
Total operating expenses	30,700,541	24,818,650	28,336,367	31,364,917	32,001,788	28,643,551	29,651,930	34,275,766	115,220,475	124,573,035	125,862,987
Loss from operations	(30,421,053)	(23,951,787)	(28,200,694)	(28,535,012)	(29,499,164)	(26,642,683)	(5,203,169)	(32,746,122)	(111,108,545)	(94,091,138)	(83,642,901)
Interest income	587,679	637,438	755,330	625,535					2,605,981	2,264,747	1,836,451
Interest expense	(2,668,837)	(2,428,671)	(2,194,783)	(656,248)					(7,948,539)	0	(25,933)
Interest and other income, net					(169,300)	380,987	396,681	312,523
Change in fair value of common stock warrants					0	228,665	259,971	(127,841)	0	360,795	806,819
Change in fair value of derivative liability	(4,315,105)	2,551,453	0	0					(1,763,652)	0	0
Loss on investment in affiliated entities	(1,681,401)	(485,841)	(173,212)	(750,103)	(3,293,741)	1,017,359	(2,092,608)	2,380,423	(3,090,557)	(1,988,567)	(6,982,664)
Other income (expense), net	263,571	140,956	127,512	(35,839)					496,200	(1,343,856)	(197,544)
Net loss before income tax benefit/(provision for income tax)	(38,235,146)	(23,536,452)	(29,685,847)	(29,351,667)	(32,962,205)	(25,015,672)	(6,639,125)	(30,181,017)	(120,809,112)	(94,798,019)	(88,205,772)
Income tax benefit	87,764	0	106,771	62,800	0	0	0	(2,169,811)	257,335	(2,169,811)	0
Net loss	(38,147,382)	(23,536,452)	(29,579,076)	(29,288,867)	$ (32,962,205)	$ (25,015,672)	$ (6,639,125)	$ (32,350,828)	(120,551,777)	(96,967,830)	(88,205,772)
Net loss attributable to non-controlling interest	485,344	445,759	191,850	69,605					1,192,558	0	0
Net loss attributable to Inovio Pharmaceuticals, Inc.	$ (37,662,038)	$ (23,090,693)	$ (29,387,226)	$ (29,219,262)					$ (119,359,219)	$ (96,967,830)	$ (88,205,772)
Net loss per share
Basic ($ per share)	$ (0.38)	$ (0.23)	$ (0.30)	$ (0.30)	$ (0.34)	$ (0.27)	$ (0.07)	$ (0.36)	$ (1.21)	$ (1.05)	$ (1.08)
Diluted ($ per share)	$ (0.38)	$ (0.25)	$ (0.30)	$ (0.30)	$ (0.34)	$ (0.27)	$ (0.08)	$ (0.36)	$ (1.21)	$ (1.05)	$ (1.09)
Revenue under collaborative research and development arrangements
Disaggregation of Revenue [Line Items]
Total revenues	$ 184,523	$ 617,427	$ 64,283	$ 2,770,712	$ 2,372,600	$ 1,813,287	$ 24,385,852	$ 1,289,046	$ 3,636,945	$ 29,860,785	$ 28,407,388
Revenue under collaborative research and development arrangements with affiliated entities
Disaggregation of Revenue [Line Items]
Total revenues	55,665	53,014	71,390	55,579	56,207	184,990	60,319	148,008	$ 235,649	$ 449,524	$ 765,828
Miscellaneous revenue, including from affiliated entities
Disaggregation of Revenue [Line Items]
Total revenues	$ 39,300	$ 196,422	$ 0	$ 3,614	$ 73,817	$ 2,591	$ 2,590	$ 92,590

Subsequent Events (Details)

Subsequent Events (Details) - USD ($)	Mar. 09, 2020	Feb. 07, 2020	May 31, 2018	Mar. 11, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 20, 2020
Subsequent Event [Line Items]
Proceeds from issuance of common stock					$ 9,089,010	$ 29,227,776	$ 94,347,922
Sales Agreement
Subsequent Event [Line Items]
Proceeds from issuance of common stock					$ 9,100,000
Sales Agreement | Common stock
Subsequent Event [Line Items]
Authorized amount			$ 100,000,000
Agent fee			3.00%		3.00%
Sale of stock, price per share ($ per share)					$ 2.78
Sales Agreement | Common stock | Subsequent Event
Subsequent Event [Line Items]
Authorized amount	$ 250,000,000	$ 200,000,000
Number of shares issued in transaction (in shares)				43,148,952
Proceeds from issuance of common stock				$ 208,200,000
Sale of stock, price per share ($ per share)				$ 4.92
Plumbline Life Sciences
Subsequent Event [Line Items]
Percentage of ownership					15.00%	15.10%
Plumbline Life Sciences | Subsequent Event
Subsequent Event [Line Items]
Percentage of ownership								19.90%

Uncategorized Items - ino-20191

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 0	[1]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	0	[2]
AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(231,366)	[2]
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	(312,310)	[1]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	231,366	[2]
Additional Paid-in Capital [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 312,310	[1]
[1]	Upon adoption of ASU 2016-09 on January 1, 2017, the Company elected to remove the forfeiture rate from the calculation of stock-based compensation and recorded a cumulative catch-up adjustment to accumulated deficit with a corresponding offset to additional paid-in-capital of $312,000.
[2]	Upon adoption of ASU 2016-01 on January 1, 2018, the Company began to measure and record equity investments, except those accounted for under the equity method of accounting that have a readily determinable fair value, at fair value and began to recognize the changes in fair value in its consolidated statements of operations, instead of recognizing unrealized gains and losses through accumulated other comprehensive income (loss), as done under the previous guidance. The Company recorded a $231,000 cumulative effect adjustment to reclassify the cumulative unrealized gain, net of tax effect, from its investment in PLS from accumulated other comprehensive loss to accumulated deficit.