Exelixis (EXEL) 10-Q 4 May 16 2016 Q1 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2016	Apr. 28, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Apr. 1, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q1
Trading Symbol	exel
Entity Registrant Name	EXELIXIS, INC.
Entity Central Index Key	939,767
Entity Filer Category	Large Accelerated Filer
Current Fiscal Year End Date	--12-30
Entity Common Stock, Shares Outstanding		228,739,657

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	[1]
Current assets:
Cash and cash equivalents	$ 276,882	$ 141,634
Short-term investments	45,235	25,426
Trade and other receivables	10,088	5,183
Inventory	2,472	2,616
Prepaid expenses and other current assets	4,791	3,806
Total current assets	339,468	178,665
Long-term investments	82,850	83,600
Long-term restricted cash and investments	2,650	2,650
Property and equipment, net	1,813	1,434
Goodwill	63,684	63,684
Other long-term assets	2,068	2,309
Total assets	492,533	332,342
Current liabilities:
Accounts payable	5,657	6,401
Accrued clinical trial liabilities	16,135	18,071
Accrued collaboration liability	14,674	10,938
Accrued compensation and benefits	6,042	3,629
Other accrued liabilities	13,671	10,007
Current portion of convertible notes	27,500	0
Current portion of deferred revenue	14,371	0
Current portion of restructuring	3,017	3,205
Total current liabilities	101,067	52,251
Long-term portion of convertible notes	281,156	301,435
Term loan payable	80,000	80,000
Long-term portion of deferred revenue	184,431	0
Long-term portion of restructuring	516	1,385
Other long-term liabilities	1,317	1,575
Total liabilities	$ 648,487	$ 436,646
Commitments
Stockholders’ deficit:
Preferred stock	$ 0	$ 0
Common stock, $0.001 par value; 400,000,000 shares authorized; issued and outstanding: 228,681,197 and 227,960,943 shares at March 31, 2016 and December 31, 2015, respectively	228	228
Additional paid-in capital	1,842,248	1,832,741
Accumulated other comprehensive loss	(42)	(232)
Accumulated deficit	(1,998,388)	(1,937,041)
Total stockholders’ deficit	(155,954)	(104,304)
Total liabilities and stockholders’ deficit	$ 492,533	$ 332,342
[1]	The condensed consolidated balance sheet as of December 31, 2015 has been derived from the audited financial statements as of that date.

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Common stock, par value, in dollars per share	$ 0.001	$ 0.001
Common stock, shares authorized	400,000,000	400,000,000
Common stock, shares issued	228,681,197	227,960,943
Common stock, shares outstanding	228,681,197	227,960,943

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues:
Net product revenues	$ 9,099	$ 9,388
License and contract revenues	6,328	0
Total revenues	15,427	9,388
Operating expenses:
Cost of goods sold	685	766
Research and development	28,926	22,282
Selling, general and administrative	34,857	9,531
Restructuring charge (recovery)	94	(431)
Total operating expenses	64,562	32,148
Loss from operations	(49,135)	(22,760)
Other income (expense), net:
Interest income and other, net	202	(7)
Interest expense	(12,414)	(12,403)
Total other income (expense), net	(12,212)	(12,410)
Net loss	$ (61,347)	$ (35,170)
Net loss per share, basic and diluted, in dollars per share	$ (0.27)	$ (0.18)
Shares used in computing basic and diluted net loss per share, in shares	228,304	195,904

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net loss		$ (61,347)	$ (35,170)
Other comprehensive income	[1]	190	60
Comprehensive loss		$ (61,157)	$ (35,110)
[1]	Other comprehensive income consisted solely of unrealized losses or gains, net on available for sale securities arising during the periods presented. There were no reclassification adjustments to net loss resulting from realized losses or gains on the sale of securities and there was no income tax expense related to other comprehensive income during those periods.

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015
Cash flows from operating activities:
Net loss	$ (61,347)		$ (35,170)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	229		297
Stock-based compensation expense	11,185		1,660
Accretion of debt discount	5,285		7,675
Accrual of interest paid in kind	1,936		0
Gain on sale of equity investment	0		(95)
Change in the fair value of warrants	0		549
Other	(1,474)		637
Changes in assets and liabilities:
Trade and other receivables	(4,938)		1,292
Inventory	144		(212)
Prepaid expenses and other current assets	(985)		(1,731)
Other long term assets	241		(115)
Accounts payable, accrued compensation and benefits, and other accrued liabilities	5,333		(6,382)
Clinical trial liabilities	(1,936)		(10,569)
Accrued collaboration liability	3,736		2,966
Restructuring liability	(1,057)		(3,024)
Other long-term liabilities	(258)		(288)
Deferred revenue	198,802		(2,576)
Net cash provided by (used in) operating activities	154,896		(45,086)
Cash flows from investing activities:
Purchases of property and equipment	(682)		(31)
Proceeds from sale of property and equipment	107		639
Proceeds from equity investment	0		95
Proceeds from maturities of restricted cash and investments	2,004		10,748
Purchase of restricted cash and investments	(2,004)		(2,684)
Proceeds from sale of investments	17		0
Proceeds from maturities of investments	30,108		54,410
Purchases of investments	(49,235)		(13,282)
Net cash (used in) provided by investing activities	(19,685)		49,895
Cash flows from financing activities:
Proceeds from issuance of common stock, net	37		0
Principal payments on debt	0		(217)
Net cash provided by (used in) financing activities	37		(217)
Net increase in cash and cash equivalents	135,248		4,592
Cash and cash equivalents at beginning of period	141,634	[1]	80,395
Cash and cash equivalents at end of period	$ 276,882		$ 84,987
[1]	The condensed consolidated balance sheet as of December 31, 2015 has been derived from the audited financial statements as of that date.

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Summary of Significant Accounting Policies	ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization Exelixis, Inc. (“Exelixis,” “we,” “our” or “us”) is a biopharmaceutical company committed to the discovery, development and commercialization of new medicines with the potential to improve care and outcomes for people with cancer. Since its founding in 1994, three medicines discovered at Exelixis have progressed through clinical development to receive regulatory approval. Currently, we are focused on advancing cabozantinib, an inhibitor of multiple tyrosine kinases including MET, AXL and VEGF receptors, which has shown clinical anti-tumor activity in more than 20 forms of cancer and is the subject of a broad clinical development program. Two separate formulations of cabozantinib have received regulatory approval to treat certain forms of kidney and thyroid cancer and are marketed for those purposes as CABOMETYX™ tablets in the United States and COMETRIQ ® capsules in both the Unites States and European Union, respectively. Another Exelixis-discovered compound, cobimetinib, a selective inhibitor of MEK marketed as COTELLIC™ has been approved in major territories including the United States and European Union, and is being evaluated for further potential indications by Roche and Genentech (a member of the Roche Group) under a collaboration with Exelixis. Basis of Consolidation The condensed consolidated financial statements include the accounts of Exelixis and those of our wholly-owned subsidiaries. These entities’ functional currency is the U.S. dollar. All intercompany balances and transactions have been eliminated. Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. In our opinion, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation of the results of operations and cash flows for the period presented have been included. We adopted a 52- or 53-week fiscal year that generally ends on the Friday closest to December 31st. Fiscal year 2016 will end on December 30, 2016, and fiscal year 2015, ended on January 1, 2016. For convenience, references in this report as of and for the fiscal periods ended April 1, 2016 and March 28, 2015, and as of and for the fiscal years ended December 30, 2016 and January 1, 2016, are indicated as being as of and for the periods ended March 31, 2016, March 31, 2015, December 31, 2016, and December 31, 2015, respectively. Operating results for the three months ended March 31, 2016 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2016 or for any future period. These financial statements and notes should be read in conjunction with the consolidated financial statements and notes thereto for the year ended December 31, 2015 , included in our Annual Report on Form 10-K filed with the SEC on February 29, 2016 . Segment Information We operate as a single reportable segment. Use of Estimates The preparation of our consolidated financial statements is in conformity with accounting principles generally accepted in the United States which requires management to make judgments, estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, and related disclosures. On an ongoing basis, management evaluates its estimates including, but not limited to, those related to revenue recognition, including for deductions from revenues (such as rebates, chargebacks, sales returns and sales allowances) and the period of performance, identification of deliverables and evaluation of milestones with respect to our collaborations , recoverability of inventory, certain accrued liabilities including clinical trial and collaboration liability accruals, and share-based compensation. We base our estimates on historical experience and on various other market-specific and other relevant assumptions that we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates. Limited Sources of Revenues and the Need to Raise Additional Capital We have incurred net losses since inception through March 31, 2016 , with the exception of the 2011 fiscal year. We anticipate net losses for the foreseeable future. For the three months ended March 31, 2016 , we incurred a net loss of $61.3 million and as of March 31, 2016 , we had an accumulated deficit of $2.0 billion . These losses have had, and will continue to have, an adverse effect on our stockholders’ deficit and working capital. Because of the numerous risks and uncertainties associated with developing drugs, we are unable to predict the extent of any future losses or whether or when we will become profitable, if at all. Excluding fiscal 2011, our research and development expenditures and selling, general and administrative expenses have exceeded our revenues for each fiscal year, and we expect to spend significant additional amounts to fund the continued development and commercialization of cabozantinib. As a result, we expect to continue to incur substantial operating expenses and, consequently, we will need to generate significant additional revenues to achieve future profitability. We launched COMETRIQ for the treatment of progressive, metastatic medullary thyroid cancer (“MTC”) in the United States in January 2013, and from the commercial launch through March 31, 2016 , we have generated $83.4 million in net revenues from the sale of COMETRIQ. Other than revenues from COMETRIQ, we have derived substantially all of our revenues since inception from collaborative research and development agreements, which depend on research funding, the achievement of milestones, and royalties we earn from any future products developed from the collaborative research. Furthermore, while CABOMETYX was approved by the FDA for the treatment of advanced renal cell carcinoma (“RCC”) on April 25, 2016, and was shipped to wholesalers and pharmacies within three days of such approval, we have only just begun to generate revenue from the sale of CABOMETYX. The amount of our net losses will depend, in part, on: the level of sales of CABOMETYX in the U.S. for the treatment of advanced RCC; our sales of COMETRIQ; achievement of clinical, regulatory and commercial milestones and the amount of royalties, if any, from sales of cabozantinib under our collaboration with Ipsen Pharma SAS (“Ipsen”); our share of the net profits and losses for the commercialization of COTELLIC in the U.S. under our collaboration with Genentech (a member of the Roche group); the amount of royalties from COTELLIC sales outside the U.S. under our collaboration with Genentech; other license and contract revenues; and, the level of our expenses, primarily with respect to expanded commercialization activities for cabozantinib. As of March 31, 2016 , we had $407.6 million in cash and investments, which included $323.3 million available for operations, $81.6 million of compensating balance investments that we are required to maintain on deposit with Silicon Valley Bank, and $2.7 million of long-term restricted investments. We anticipate that our current cash and cash equivalents, and short-term investments available for operations, and product revenues, will enable us to maintain our operations for a period of at least 12 months following the filing date of this report. Our capital requirements will depend on many factors, and we may need to use available capital resources and raise additional capital significantly earlier than we currently anticipate. Revenue Recognition We recognize revenue from product sales and from license fees, milestones, contingent payments and royalties earned on research, collaboration and license arrangements. See “Note 1 - Organization and Summary of Significant Accounting Policies” to our Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2015 for a description of our revenue recognition policies for product sales discounts and allowances, license and contract revenues under our collaboration agreement with Genentech, Inc. and our Patient Assistance Program. Net Product Revenues We recognize revenue when it is both realized or realizable and earned, meaning persuasive evidence of an arrangement exists, delivery has occurred, title has transferred, the price is fixed or determinable, there are no remaining customer acceptance requirements, and collectability of the resulting receivable is reasonably assured. For product sales in the United States, this generally occurs upon delivery of the product to the specialty pharmacy. For product sales in Europe, this generally occurs when our European distribution partner, Swedish Orphan Biovitrum (“Sobi”), has accepted the product. We sell our product, COMETRIQ, in the United States to a specialty pharmacy that benefits from customer incentives and has a right of return. Prior to 2015, COMETRIQ had limited sales history and we could not reliably estimate expected future returns, discounts and rebates of the product at the time the product was sold to the specialty pharmacy, therefore we recognized revenue when the specialty pharmacy provided the product to a patient based on the fulfillment of a prescription, frequently referred to as the “sell-through” revenue recognition model. We have established sufficient historical experience and data to reasonably estimate expected future returns of the product and the discounts and rebates due to payors at the time of shipment to the specialty pharmacy. Accordingly, beginning in January 2015 we began to recognize revenue upon delivery to our U.S. specialty pharmacy. This approach is frequently referred to as the “sell-in” revenue recognition model. In connection with the change in the timing of recognition of U.S. COMETRIQ sales, we recorded a one-time adjustment to recognize revenue and related costs that had previously been deferred under the “sell-through” revenue recognition model, resulting in the additional recognition of gross product revenues of $2.6 million and a nominal amount of cost of goods sold for the three months ended March 31, 2015 ; there were no such additional amounts recorded during the comparable period in 2016 . We also utilize the “sell-in” revenue recognition model for sales to Sobi for all periods presented. Once Sobi has accepted the product, the product is generally no longer subject to return; therefore, we record revenue at the time Sobi has accepted the product. As described further in “Note 2 - Research and Collaboration Agreements”, we are required to provide Sobi with notice of termination under the terms of our collaboration and license agreement with Ipsen for the commercialization and further development of cabozantinib. Pursuant to our commercialization agreement with Sobi, we expect to repurchase the remaining product on hand from Sobi at the termination of that agreement. During the three months ended March 31, 2016 , we recorded reserves for expected future returns from Sobi and our specialty pharmacy in the United States totaling $0.5 million ; there were no such reserves recorded during the comparable period in 2015 . License and Contract Revenues We enter into corporate collaboration and license agreements under which we may obtain upfront license fees, research funding, and contingent, milestone and royalty payments. Our deliverables under these arrangements may include intellectual property rights, distribution rights, delivery of manufactured product, participation on joint steering committees and/or research and development services. In order to account for the multiple-element arrangements, we identify the deliverables included within the arrangement and evaluate whether the delivered elements under these arrangements have value to our collaboration partner on a stand-alone basis and represent separate units of accounting. Analyzing the arrangement to identify deliverables requires the use of judgment, and each deliverable may be an obligation to deliver future goods or services, a right or license to use an asset, or another performance obligation. If we determine that multiple deliverables exist, the consideration is allocated to one or more units of accounting based upon the best estimate of the selling price of each deliverable. The selling price used for each deliverable will be based on vendor-specific objective evidence, if available, third-party evidence if vendor-specific objective evidence is not available, or estimated selling price if neither vendor-specific or third-party evidence is available. A delivered item or items that do not qualify as a separate unit of accounting within the arrangement shall be combined with the other applicable undelivered items within the arrangement. The allocation of arrangement consideration and the recognition of revenue then shall be determined for those combined deliverables as a single unit of accounting. For a combined unit of accounting, non-refundable upfront fees are recognized in a manner consistent with the final deliverable, which has generally been ratably over the period of continued involvement. Amounts received in advance of performance are recorded as deferred revenue. Upfront fees are classified as license revenues in our consolidated statements of operations. We consider sales-based contingent payments to be royalty revenue which is generally recognized at the date the contingency is achieved. Royalties are classified as license revenues in our consolidated statements of operations. For certain contingent payments under collaboration and license arrangements, we recognize revenue using the milestone method. Under the milestone method a payment that is contingent upon the achievement of a substantive milestone is recognized in its entirety in the period in which the milestone is achieved. A milestone is an event: (i) that can be achieved based in whole or in part on either our performance or on the occurrence of a specific outcome resulting from our performance, (ii) for which there is substantive uncertainty at the date the arrangement is entered into that the event will be achieved and (iii) that would result in additional payments being due to us. The determination that a milestone is substantive requires estimation and judgment and is made at the inception of the arrangement. Milestones are considered substantive when the consideration earned from the achievement of the milestone is: (i) commensurate with either our performance to achieve the milestone or the enhancement of value of the item delivered as a result of a specific outcome resulting from our performance to achieve the milestone, (ii) relates solely to past performance and (iii) reasonable relative to all deliverables and payment terms in the arrangement. In making the determination as to whether a milestone is substantive or not, we consider all facts and circumstances relevant to the arrangement, including factors such as the scientific, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required to achieve the respective milestone and whether any portion of the milestone consideration is related to future performance or deliverables. Recently Issued Accounting Pronouncements In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2016-09, Improvements to Employee Share-Based Payment Accounting , ( “ ASU 2016-09”) . ASU 2016-09 is aimed at the simplification of several aspects of the accounting for employee share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for all interim and annual reporting periods beginning after December 15, 2016. Early adoption is permitted. We are currently evaluating the impact that the adoption of ASU 2016-09 will have on our consolidated financial statements and related disclosures. In April 2015, the FASB issued Accounting Standards Update No. 2015-05, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement , ( “ ASU 2015-05”) . ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 was effective for all interim and annual reporting periods beginning after December 15, 2015 and therefore we adopted ASU 2015-05 in the three months ended March 31, 2016 on a prospective basis. The adoption of ASU 2015-05 did not have a material impact on our Condensed Consolidated Statements of Operations for the three months ended March 31, 2016 and is not expected to have a material effect on our Consolidated Financial Statements in future periods.

Research and Collaboration Agre

Research and Collaboration Agreements	3 Months Ended
	Mar. 31, 2016
Research And Collaboration Agreements [Abstract]
Research and Collaboration Agreements	RESEARCH AND COLLABORATION AGREEMENTS Ipsen Collaboration On February 29, 2016, we entered into a collaboration and license agreement (the “Agreement”) with Ipsen for the commercialization and further development of cabozantinib. Pursuant to the terms of the Agreement, Ipsen will have exclusive commercialization rights for current and potential future cabozantinib indications outside of the United States, Canada and Japan. We have agreed to collaborate on the development of cabozantinib for current and potential future indications. In consideration for the exclusive license and other rights contained in the Agreement, Ipsen paid us an upfront nonrefundable payment of $200.0 million in March 2016. We will be eligible to receive development and regulatory milestones, totaling up to $252.5 million , including a $60.0 million milestone payment upon approval of cabozantinib by the EMA in second-line RCC, milestone payments of $10.0 million and $40.0 million upon the filing and the approval of cabozantinib in second-line hepatocellular carcinoma, and additional milestones for other future indications. We will also be eligible to receive two $10.0 million milestone payments upon the launch of the product in the first two of the following countries: Germany, France, Italy, Spain and the United Kingdom. The Agreement also provides that we will be eligible to receive contingent payments of up to $525.0 million associated with the achievement of specified sales volumes. We will also receive royalties on net sales of cabozantinib outside of the United States, Canada and Japan. We will receive a 2% royalty on the initial $50.0 million of net sales, and a 12% royalty on the next $100.0 million of net sales. After the initial $150.0 million of sales, we will receive a tiered royalty of 22% to 26% on annual net sales; these tiers will reset each calendar year. We are primarily responsible for funding cabozantinib related development costs for existing trials; global development costs for potential future trials will be shared between the parties, with Ipsen to reimburse us for 35% of such costs. Pursuant to the terms of the Agreement, we will remain responsible for the manufacture and supply of cabozantinib for all development and commercialization activities under the Agreement. As part of the Agreement, we entered into a supply agreement which provides that through the end of the second quarter of 2018, we will supply finished, labeled product to Ipsen for distribution in the territories outside of the United States, Canada and Japan, and from the end of the second quarter of 2018 forward, we will supply primary packaged bulk tablets to Ipsen. No manufacturing rights were granted to Ipsen. The agreement contains multiple elements, and the deliverables under the Agreement consist of intellectual property licenses, delivery of cabozantinib to Ipsen for all development and commercial activities, research and development services, and participation on the joint steering and development committees (as defined in the Agreement) with Ipsen. These deliverables are non-contingent in nature. The Company determined that these deliverables do not have stand-alone value, because each one of them has value only if the Company meets its obligation to provide Ipsen with cabozantinib, which the Company deems to be the predominant deliverable under the Agreement. The Company also determined that the level of effort required of the Company to meet its obligations under the Agreement is not expected to vary significantly over the life of the Agreement. Accordingly, the Company combined these deliverables into a single unit of accounting and allocated the entire arrangement consideration to that combined unit of accounting. As a result, the upfront payment of $200.0 million , received in the first quarter of 2016 is being recognized ratably over the effective term of the agreement, which is early 2030, the current estimated patent expiration of cabozantinib in the European Union. We have also determined that the $60.0 million milestone payment we are eligible to receive upon the approval of cabozantinib by the EMA in second-line RCC is not substantive due to the relatively low degree of uncertainty and relatively low amount of effort required on our part to achieve the milestone as of the date the agreement; Upon achieving the milestone, the $60.0 million to which we are contractually entitled will be deferred and recognized ratably over the remaining term of the Agreement. We have determined that the remaining development and regulatory milestones are substantive and will be recognized as revenue in the periods in which they are achieved. We consider the contingent payments due to us upon the achievement of specified sales volumes to be similar to royalty payments. During the three months ended March 31, 2016 , we have recognized $1.2 million in license revenue under the Agreement. As of March 31, 2016 , short- and long-term deferred revenue relating to the Agreement was $14.4 million and $184.4 million , respectively. In connection with the establishment of the Agreement with Ipsen, we are required to provide Sobi with notice of termination as Ipsen will become responsible for the continued distribution and commercialization of COMETRIQ for the approved MTC indication in territories supported by Sobi. Pursuant to our commercialization agreement with Sobi we are required to pay a termination fee. During the three months ended March 31, 2016 , we recorded a $2.8 million accrual for the estimated termination fee to be paid to Sobi, which is included in Selling, general and administrative expenses in the accompanying Condensed Consolidated Statements of Operations. Additionally, pursuant to our commercialization agreement with Sobi, we expect to repurchase unsold product from Sobi and have recorded a returns reserve of $0.4 million during the three months ended March 31, 2016 , which is included in Net product revenues in the accompanying Condensed Consolidated Statements of Operations. Genentech Collaboration In December 2006, we out-licensed the development and commercialization of cobimetinib to Genentech (a member of the Roche group) pursuant to a worldwide collaboration agreement. We discovered cobimetinib internally and advanced the compound to investigational new drug (“IND”) status. Genentech paid upfront and milestone payments of $25.0 million in December 2006 and $15.0 million in January 2007 upon signing of the collaboration agreement and with the submission of the IND application for cobimetinib. Under the terms of the agreement, we were responsible for developing cobimetinib through the determination of the maximum-tolerated dose in a phase 1 clinical trial, and Genentech had the option to co-develop cobimetinib, which Genentech could exercise after receipt of certain phase 1 data from us. In March 2008, Genentech exercised its option to co-develop cobimetinib. In March 2009, we granted to Genentech an exclusive worldwide revenue-bearing license to cobimetinib, at which point Genentech became responsible for completing the phase 1 clinical trial and subsequent clinical development. The U.S. Food and Drug Administration approved cobimetinib in the United States under the brand name COTELLIC on November 10, 2015. It is indicated in combination with vemurafenib as a treatment for patients with BRAF V600E or V600K mutation-positive advanced melanoma. COTELLIC in combination with vemurafenib has also been approved in multiple other territories including the European Union and Canada. Under the terms of our collaboration agreement with Genentech for cobimetinib, we are entitled to a share of U.S. profits and losses for cobimetinib. The profit and loss share has multiple tiers: we are entitled to 50% of profits and losses from the first $200.0 million of U.S. actual sales, decreasing to 30% of profits and losses from U.S. actual sales in excess of $400.0 million . We are entitled to low double-digit royalties on ex-U.S. net sales. In November 2013, we exercised an option under the collaboration agreement to co-promote in the United States, if commercialized. Following the approval of COTELLIC in the United States in November 2015, we began fielding 25% of the sales force promoting COTELLIC in combination with vemurafenib as a treatment for patients with BRAF V600E or V600K mutation-positive advanced melanoma. We recorded net losses of $7.3 million and $3.0 million under the collaboration agreement during the three months ended March 31, 2016 and 2015, respectively; those costs are included in Selling, general and administrative expenses on the accompanying Condensed Consolidated Statements of Operations. A portion of the liability for those costs, identified as Accrued collaboration liability on the accompanying Condensed Consolidated Balance Sheets, includes commercialization expenses that Genentech has allocated to the collaboration but are in dispute. To date, we believe Genentech’s cost and revenue allocations for COTELLIC, as determined exclusively by Genentech, have been contrary to the applicable terms of the collaboration agreement. We have raised this concern with Genentech, along with other material concerns regarding Genentech’s performance under the collaboration agreement, but thus far have been unable to come to resolution on any of these issues. Accordingly, on May 3, 2016, we issued a formal notice of dispute to Genentech, per the collaboration agreement’s dispute resolution procedures. This notice asserts claims against Genentech related to its clinical development, pricing and commercialization of COTELLIC, and cost and revenue allocations arising from COTELLIC’s commercialization in the United States. If the dispute is not resolved within thirty days of Genentech’s receipt of this notice, we intend to initiate an arbitration. We also recognized license revenues of $0.1 million for royalties on ex-U.S. net sales of COTELLIC during the three months ended March 31, 2016 . We recognized no such royalties during the same period in 2015. Other Collaborations During the three months ended March 31, 2016 , we recognized $5.0 million in contract revenues from a contingent payment received from Merck related to its worldwide license of our PI3K-delta program. See “Note 2 - Research and Collaboration Agreements” to our Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2015 for a description of our existing collaboration agreements.

Restructurings

Restructurings	3 Months Ended
	Mar. 31, 2016
Restructuring Charges [Abstract]
Restructurings	RESTRUCTURINGS Between March 2010 and May 2013, we implemented five restructurings (which we refer to collectively as the “2010 Restructurings”) to manage costs and as a consequence of our decision in 2010 to focus our proprietary resources and development efforts on the development and commercialization of cabozantinib. In September 2014, as a consequence of the failure of COMET-1, one of our two phase 3 pivotal trials of cabozantinib in metastatic castration-resistant prostate cancer, we initiated a restructuring (which we refer to as the “2014 Restructuring”) to enable us to focus our financial resources on the phase 3 pivotal trials of cabozantinib in advanced renal cell carcinoma and advanced hepatocellular carcinoma. See “Note 3 - Restructurings” to our Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2015 for additional information about the restructurings. For the three months ended March 31, 2016 and 2015 , we recorded a restructuring charge of $0.1 million and a recovery of $0.4 million , respectively, for the restructurings. Both periods included the effect of the passage of time on our discounted cash flow computations (“accretion expense”) for the exit, in prior periods, of certain of our South San Francisco buildings. During the three months ended March 31, 2015 we recorded $0.9 million in recoveries related to the sale of fully depreciated assets, net of asset impairments, which was partially offset by $0.3 million in additional charges due to changes in assumptions regarding anticipated sublease activities. The total outstanding restructuring liability is included in the current and long-term portion of restructuring on the accompanying Condensed Consolidated Balance Sheets. The changes of these liabilities, which related primarily to facility charges during the three months ended March 31, 2016 , are summarized in the following table (in thousands): 2010 Restructurings 2014 Restructuring Total Restructuring liability as of December 31, 2015 $ 4,087 $ 503 $ 4,590 Restructuring charge 87 7 94 Proceeds from sale of assets — 34 34 Cash payments, net (846 ) (305 ) (1,151 ) Other items — (34 ) (34 ) Restructuring liability as of March 31, 2016 $ 3,328 $ 205 $ 3,533 We expect to pay accrued facility charges of $3.5 million , net of cash received from our subtenants, through the end of our lease terms of the buildings, the last of which ends in 2017. We expect to incur additional restructuring charges of approximately $0.2 million relating to the effect of accretion expense through to the end of the building lease terms.

Cash and Investments

Cash and Investments	3 Months Ended
	Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Cash and Investments	CASH AND INVESTMENTS All of our cash equivalents and investments are classified as available-for-sale. The following tables summarize cash and cash equivalents, investments, and restricted cash and investments by balance sheet line item as of March 31, 2016 and December 31, 2015 (in thousands): March 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash and cash equivalents $ 276,881 $ 1 $ — $ 276,882 Short-term investments 45,179 74 (18 ) 45,235 Long-term investments 82,841 9 82,850 Long-term restricted cash and investments 2,650 — 2,650 Total cash and investments $ 407,551 $ 84 $ (18 ) $ 407,617 December 31, 2015 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash and cash equivalents $ 141,634 $ — $ — $ 141,634 Short-term investments 25,484 5 (63 ) 25,426 Long-term investments 83,665 2 (67 ) 83,600 Long-term restricted cash and investments 2,650 — — 2,650 Total cash and investments $ 253,433 $ 7 $ (130 ) $ 253,310 Under our loan and security agreement with Silicon Valley Bank, we are required to maintain compensating balances on deposit in one or more investment accounts with Silicon Valley Bank or one of its affiliates. The total collateral balances were $81.6 million as of both March 31, 2016 and December 31, 2015 and are reflected in our Condensed Consolidated Balance Sheets in short- and long-term investments. See “Note 7 - Debt” to our Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2015 , for more information regarding the collateral balance requirements under our Silicon Valley Bank loan and security agreement. The following tables summarize our cash equivalents and investments by security type as of March 31, 2016 and December 31, 2015 . The amounts presented exclude cash, but include investments classified as cash equivalents (in thousands): March 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 129,887 $ — $ — $ 129,887 Commercial paper 177,934 1 — 177,935 Corporate bonds 68,297 46 (18 ) 68,325 U.S. Treasury and government sponsored enterprises 29,073 37 — 29,110 Total investments $ 405,191 $ 84 $ (18 ) $ 405,257 December 31, 2015 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 72,000 $ — $ — $ 72,000 Commercial paper 78,155 — — 78,155 Corporate bonds 72,205 4 (118 ) 72,091 U.S. Treasury and government sponsored enterprises 28,434 1 (12 ) 28,423 Marketable equity security 16 2 — 18 Total investments $ 250,810 $ 7 $ (130 ) $ 250,687 During the three months ended March 31, 2016 , we sold a single marketable equity security; we realized a loss on the sale of less than $1,000 . There were no other sales of investments during the three months ended March 31, 2016 and 2015 . All of our investments are subject to a quarterly impairment review. During the three months ended March 31, 2016 and 2015 , we did not record any other-than-temporary impairment charges on our available-for-sale securities. As of March 31, 2016 , there were 19 investments in an unrealized loss position with gross unrealized losses of $18 thousand and an aggregate fair value $37.9 million . Investments in an unrealized loss position are primarily comprised of corporate bonds. The unrealized losses were not attributed to credit risk, but rather associated with the changes in interest rates. Based on the scheduled maturities of our investments, we concluded that the unrealized losses in our investment securities are not other-than-temporary, as it is more likely than not that we will hold these investments for a period of time sufficient for a recovery of our cost basis. The following table summarizes the fair value of securities classified as available-for-sale by contractual maturity as of March 31, 2016 (in thousands): Mature within One Year After One Year through Two Years Fair Value Money market funds $ 129,887 $ — $ 129,887 Commercial paper 177,935 — 177,935 Corporate bonds 66,323 2,002 68,325 U.S. Treasury and government sponsored enterprises 27,860 1,250 29,110 Total investments $ 402,005 $ 3,252 $ 405,257 Cash is excluded from the table above. The classification of certain compensating balances and restricted investments are dependent upon the term of the underlying restriction on the asset and not the maturity date of the investment. Therefore, certain long-term investments and long-term restricted cash and investments have contractual maturities within one year.

Inventory

Inventory	3 Months Ended
	Mar. 31, 2016
Inventory Disclosure [Abstract]
Inventory	INVENTORY Inventory consists of the following (in thousands): March 31, December 31, Raw materials $ 1,032 $ 1,037 Work in process 1,720 2,251 Finished goods 734 583 Total 3,486 3,871 Less: non-current portion included in Other assets (1,014 ) (1,255 ) Inventory $ 2,472 $ 2,616 We generally relieve inventory on a first-expiry, first-out basis. Write-downs related to expiring inventory are charged to cost of goods sold. Such write-downs were nominal for three months ended March 31, 2016 and 2015 . The non-current portion of inventory recorded as other assets consists of raw materials and a portion of the active pharmaceutical ingredient which is included in work in process. There were no other write-downs for obsolete or excess inventory.

Debt

Debt	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Debt	DEBT The amortized carrying amount of our debt consists of the following (in thousands): March 31, December 31, Convertible Senior Subordinated Notes due 2019 $ 203,900 $ 198,708 Secured Convertible Notes due 2018 104,756 102,727 Term loan payable 80,000 80,000 Total debt 388,656 381,435 Less: current portion (27,500 ) — Long-term debt $ 361,156 $ 381,435 See “Note 7 - Debt” to our Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2015 , for additional information on the terms of our debt, including a description of the conversion features of the of 4.25% Convertible Senior Subordinated Notes due 2019 (the “2019 Notes”) and our Secured Convertible Notes due June 2018 (the “Deerfield Notes”). Convertible Senior Subordinated Notes due 2019 In August 2012, we issued and sold $287.5 million aggregate principal amount of the 2019 Notes. As of both March 31, 2016 and December 31, 2015 , $287.5 million of aggregate principal amount of the 2019 Notes remains outstanding. The 2019 Notes bear interest at a rate of 4.25% per annum, payable semi-annually in arrears on February 15 and August 15 of each year. The following is a summary of the liability component of the 2019 Notes (in thousands): March 31, December 31, Net carrying amount of the liability component $ 203,900 $ 198,708 Unamortized discount of the liability component 83,600 88,792 Face amount of the 2019 Notes $ 287,500 $ 287,500 The debt discount and debt issuance costs will be amortized as interest expense through August 2019. The following is a summary of interest expense for the 2019 Notes (in thousands): Three Months Ended March 31, 2016 2015 Stated coupon interest $ 3,055 $ 3,055 Amortization of debt discount and debt issuance costs 5,191 4,721 Total interest expense $ 8,246 $ 7,776 The balance of unamortized fees and costs was $2.4 million and $2.6 million as of March 31, 2016 and December 31, 2015 , respectively, which is recorded as a reduction of the carrying amount of the 2019 Notes on the accompanying Condensed Consolidated Balance Sheets. Secured Convertible Notes due June 2018 As of March 31, 2016 and December 31, 2015 , the outstanding principal balance on the Deerfield Notes was $105.8 million and $103.8 million , respectively, which, subject to certain limitations, is payable in cash or in stock at our discretion. Beginning on July 2, 2015, the outstanding principal amount of the Deerfield Notes bears interest at the rate of 7.5% per annum to be paid in cash, quarterly in arrears, and 7.5% per annum to be paid in kind, quarterly in arrears, for a total interest rate of 15% per annum. Through July 1, 2015, the outstanding principal amount of the Deerfield Notes bore interest in the annual amount of $6.0 million , payable quarterly in arrears. The following is a summary of interest expense for the Deerfield Notes (in thousands): Three Months Ended March 31, 2016 2015 Stated coupon interest paid in cash $ 1,936 $ 1,479 Amortization of debt discount, debt issuance costs and accrual of interest paid in kind 2,029 2,947 Total interest expense $ 3,965 $ 4,426 The balance of unamortized fees and costs was $0.6 million and $0.7 million as of March 31, 2016 and December 31, 2015 , respectively, which is recorded as a reduction of the carrying amount of the Deerfield Notes on the accompanying Condensed Consolidated Balance Sheets. Effective March 4, 2015, upon notification of our election to extend the maturity date to July 1, 2018, we began to amortize the remaining unamortized discount, fees and costs through July 1, 2018 using the effective interest method and an effective interest rate of 15.3% . We were required to make an additional mandatory prepayment on the Deerfield Notes in January 2015 and 2016 equal to 15% of certain revenues from collaborative arrangements, which we refer to as Development/Commercialization Revenue, received during the prior fiscal year, subject to a maximum prepayment amount of $27.5 million . We made no such mandatory prepayments due to the fact that we received no such revenues during the fiscal year ended December 31, 2014 and Deerfield’s election not to receive the mandatory prepayment in January 2016. As a result of the extension of the maturity date of the Deerfield Notes to July 1, 2018, our obligation to make annual mandatory prepayments equal to 15% of Development/Commercialization Revenue received by us during the prior fiscal year will continue to apply in January 2017 and January 2018. However, we will only be obligated to make any such annual mandatory prepayment if the note holders provide notice to us of their election to receive the prepayment. Pursuant to this requirement, we may be required make a mandatory prepayment of $27.5 million in January 2017 as a result of the upfront payment of $200.0 million received in March 2016 in consideration for the exclusive license and other rights contained in the collaboration and license agreement with Ipsen. That portion of the Deerfield Notes is included in current liabilities. The definition of “Development/Commercialization Revenue” expressly excludes any sale or distribution of drug or pharmaceutical products in the ordinary course of our business, and any proceeds from any Intellectual Property Sale, but would include our share of the net profits from the commercialization of cobimetinib in the U.S. and the receipt of royalties from cobimetinib sales outside the U.S., if any.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS The following table sets forth the fair value of our financial assets and liabilities that were measured and recorded on a recurring basis as of March 31, 2016 and December 31, 2015 . We did not have any financial liabilities that were measured and recorded on a recurring basis or Level 3 investments as of March 31, 2016 . The amounts presented exclude cash, but include investments classified as cash equivalents (in thousands): March 31, 2016 Level 1 Level 2 Total Money market funds $ 129,887 $ — $ 129,887 Commercial paper — 177,935 177,935 Corporate bonds — 68,325 68,325 U.S. Treasury and government sponsored enterprises — 29,110 29,110 Total financial assets $ 129,887 $ 275,370 $ 405,257 December 31, 2015 Level 1 Level 2 Total Money market funds $ 72,000 $ — $ 72,000 Commercial paper — 78,155 78,155 Corporate bonds — 72,091 72,091 U.S. Treasury and government sponsored enterprises — 28,423 28,423 Marketable equity securities 18 — 18 Total financial assets $ 72,018 $ 178,669 $ 250,687 The estimated fair value of our financial instruments that are carried at amortized cost for which it is practicable to determine a fair value was as follows (in thousands) : March 31, 2016 December 31, 2015 Carrying Amount Fair Value Carrying Amount Fair Value 2019 Notes $ 203,900 $ 286,149 $ 198,708 $ 336,260 Deerfield Notes $ 104,756 $ 105,166 $ 102,727 $ 101,096 Term loan payable $ 80,000 $ 79,929 $ 80,000 $ 79,815 The carrying amounts of cash, trade and other receivables, accounts payable, accrued clinical trial liabilities, accrued compensation and benefits, accrued collaboration liability, and other accrued liabilities approximate their fair values and are excluded from the tables above. The following methods and assumptions were used to estimate the fair value of each class of financial instrument for which it is practicable to estimate a value: • When available, we value investments based on quoted prices for those financial instruments, which is a Level 1 input. Our remaining investments are valued using third-party pricing sources, which use observable market prices, interest rates and yield curves observable at commonly quoted intervals of similar assets as observable inputs for pricing, which is a Level 2 input. • The 2019 Notes are valued using a third-party pricing model that is based in part on average trading prices, which is a Level 2 input. The 2019 Notes are not marked-to-market and are shown at their initial fair value less the unamortized discount; the portion of the value allocated to the conversion option is included in Stockholders’ deficit on the accompanying Condensed Consolidated Balance Sheets. • We estimate the fair value of our other debt instruments, where possible, using the net present value of the payments. For the term loan, we use an interest rate that is consistent with money-market rates that would have been earned on our non-interest-bearing compensating balances as our discount rate, which is a Level 2 input. For the Deerfield Notes, we used a discount rate of 16.1% , which we estimate as our current borrowing rate for similar debt as of March 31, 2016 , which is a Level 3 input.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2016
Share-based Compensation [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION We recorded and allocated employee stock-based compensation expense for our equity incentive plans and our 2000 Employee Stock Purchase Plan (“ESPP”) as follows (in thousands): Three Months Ended March 31, 2016 2015 Research and development expense $ 5,564 $ 627 Selling, general and administrative expense 5,621 1,033 Total employee stock-based compensation expense $ 11,185 $ 1,660 We use the Black-Scholes Merton option pricing model to value our stock options. The weighted average grant-date fair value of our stock options and ESPP purchases was as follows: Three Months Ended March 31, 2016 2015 Stock options $ 2.51 $ 1.35 ESPP $ 2.31 $ 0.70 The fair value of employee stock option awards and ESPP purchases was estimated using the following assumptions: Stock Options Three Months Ended March 31, 2016 2015 Risk-free interest rate 1.16 % 1.20 % Dividend yield — % — % Volatility 79 % 95 % Expected life 4.3 years 4.5 years Employee Stock Purchase Plan Three Months Ended March 31, 2016 2015 Risk-free interest rate 0.51 % 0.11 % Dividend yield — % — % Volatility 81 % 96 % Expected life 6 months 6 months The expected life computation is based on historical exercise patterns and post-vesting termination behavior. We considered implied volatility as well as our historical volatility in developing our estimate of expected volatility. A summary of all stock option activity for the three months ended March 31, 2016 is presented below (dollars in thousands , except per share amounts): Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Options outstanding at December 31, 2015 27,425,854 $ 4.22 Granted 2,062,850 $ 4.17 Exercised (21,500 ) $ 1.70 Forfeited (116,788 ) $ 3.26 Options outstanding at March 31, 2016 29,350,416 $ 4.22 4.97 years $ 28,038 Exercisable at March 31, 2016 18,979,572 $ 4.23 4.34 years $ 20,380 As of March 31, 2016 , a total of 3,439,435 shares were available for grant under our stock option plans. As of March 31, 2016 , $18.0 million of total unrecognized compensation expense related to employee stock options was expected to be recognized over a weighted-average period of 2.82 years . On March 7, 2016, as a result of the FDA’s acceptance of our NDA submission, the Compensation Committee of the Board of Directors of Exelixis convened to determine we had met certain performance objectives related to performance-based stock options granted to employees in 2014 and 2015. As a result of this determination, 2,955,464 performance-based stock options vested on March 7, 2016. Previously, we had expensed $3.3 million in employee stock-based compensation expense related to those options, and we recorded an additional $0.4 million during the three months ended March 31, 2016 . We have an additional 2,914,839 outstanding unvested stock options as of March 31, 2016 with an estimated grant date fair value of $3.7 million which were granted to employees in 2014 and 2015 and are subject to performance objectives set by the Compensation Committee of our Board of Directors. As of March 31, 2016 , we considered the achievement of the performance objectives was probable and had, therefore, recorded $3.4 million of stock-based compensation expense in connection with such awards. On April 28, 2016, as a result of the FDA’s approval of our NDA submission, the Compensation Committee of the Board of Directors of Exelixis convened to determine we had met those performance objectives. The remaining $0.3 million of the expense for these awards will be recognized during the three months ended June 30, 2016. A summary of all restricted stock unit (“RSU”) activity for the three months ended March 31, 2016 is presented below (dollars in thousands , except per share amounts): Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Awards outstanding at December 31, 2015 1,002,188 $ 5.16 Awarded 1,996,441 $ 4.23 Released (1,110,549 ) $ 4.25 Forfeited (3,559 ) $ 5.87 Awards outstanding at March 31, 2016 1,884,521 $ 4.71 1.80 years $ 7,632 As of March 31, 2016 , $4.1 million of total unrecognized compensation expense related to employee RSUs was expected to be recognized over a weighted-average period of 2.92 years . During the three months ended March 31, 2016 , we made a bonus payment made to our employees in the form of 1,072,833 shares of fully-vested restricted stock units which have a grant date fair value of $4.5 million .

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Net Loss Per Share	NET LOSS PER SHARE The following table sets forth a reconciliation of basic and diluted net loss per share (in thousands, except per share amounts): Three Months Ended March 31, 2016 2015 Numerator: Net loss $ (61,347 ) $ (35,170 ) Denominator: Shares used in computing basic and diluted net loss per share 228,304 195,904 Net loss per share, basic and diluted $ (0.27 ) $ (0.18 ) The following table sets forth outstanding potentially dilutive shares of common stock that are not included in the computation of diluted net loss per share because, to do so would be anti-dilutive (in thousands): March 31 2016 2015 Convertible Senior Subordinated Notes due 2019 54,118 54,118 Secured Convertible Notes due 2018 33,890 33,890 Outstanding stock options, unvested RSUs and ESPP contributions 31,364 29,591 Warrants 1,000 1,000 Total potentially dilutive shares 120,372 118,599 The warrants are participating securities and the warrant holders do not have a contractual obligation to share in our losses.

Concentrations of Credit Risk

Concentrations of Credit Risk	3 Months Ended
	Mar. 31, 2016
Risks and Uncertainties [Abstract]
Concentrations of Credit Risk	CONCENTRATIONS OF CREDIT RISK Financial instruments that potentially subject us to concentrations of credit risk are primarily trade and other receivables and investments. Investments consist of money market funds, taxable commercial paper, corporate bonds with high credit quality, U.S. Treasury and government sponsored enterprises, and municipal bonds. All investments are maintained with financial institutions that management believes are creditworthy. Trade and other receivables are unsecured and are concentrated in the pharmaceutical and biotechnology industries. Accordingly, we may be exposed to credit risk generally associated with pharmaceutical and biotechnology companies. We have incurred no bad debt expense since inception. As of March 31, 2016 , 40% of our trade receivables are with the specialty pharmacy that sells COMETRIQ in the United States and 4% are with our European distribution partner. Both of these customers pay promptly and within their respective payment terms. All of our long-lived assets are located in the United States. We have operations primarily in the United States, while some of our collaboration partners have headquarters outside of the United States and some of our clinical trials for cabozantinib are also conducted outside of the United States. The following table shows the percentage of revenues earned in the United States and European Union. Three Months Ended March 31, 2016 2015 Percentage of revenues earned in the United States 88 % 86 % Percentage of revenues earned in the European Union 12 % 14 % We recorded a $0.2 million loss and a $0.2 million gain relating to foreign exchange fluctuations for three months ended March 31, 2016 and 2015 , respectively. The following table sets forth the percentage of revenues recognized by customer that represent 10% or more of total revenues: Three Months Ended March 31, 2016 2015 Product sales: Diplomat Specialty Pharmacy 55 % 86 % Swedish Orphan Biovitrum 4 % 14 % Collaboration agreements: Merck 32 % — %

Organization and Summary of S17

Organization and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	Organization Exelixis, Inc. (“Exelixis,” “we,” “our” or “us”) is a biopharmaceutical company committed to the discovery, development and commercialization of new medicines with the potential to improve care and outcomes for people with cancer. Since its founding in 1994, three medicines discovered at Exelixis have progressed through clinical development to receive regulatory approval. Currently, we are focused on advancing cabozantinib, an inhibitor of multiple tyrosine kinases including MET, AXL and VEGF receptors, which has shown clinical anti-tumor activity in more than 20 forms of cancer and is the subject of a broad clinical development program. Two separate formulations of cabozantinib have received regulatory approval to treat certain forms of kidney and thyroid cancer and are marketed for those purposes as CABOMETYX™ tablets in the United States and COMETRIQ ® capsules in both the Unites States and European Union, respectively. Another Exelixis-discovered compound, cobimetinib, a selective inhibitor of MEK marketed as COTELLIC™ has been approved in major territories including the United States and European Union, and is being evaluated for further potential indications by Roche and Genentech (a member of the Roche Group) under a collaboration with Exelixis.
Basis of Consolidation	Basis of Consolidation The condensed consolidated financial statements include the accounts of Exelixis and those of our wholly-owned subsidiaries. These entities’ functional currency is the U.S. dollar. All intercompany balances and transactions have been eliminated.
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (“SEC”). Accordingly, they do not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements. In our opinion, all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation of the results of operations and cash flows for the period presented have been included.
Fiscal Period	We adopted a 52- or 53-week fiscal year that generally ends on the Friday closest to December 31st. Fiscal year 2016 will end on December 30, 2016, and fiscal year 2015, ended on January 1, 2016. For convenience, references in this report as of and for the fiscal periods ended April 1, 2016 and March 28, 2015, and as of and for the fiscal years ended December 30, 2016 and January 1, 2016, are indicated as being as of and for the periods ended March 31, 2016, March 31, 2015, December 31, 2016, and December 31, 2015, respectively.
Segment Information	Segment Information We operate as a single reportable segment.
Use of Estimates	Use of Estimates The preparation of our consolidated financial statements is in conformity with accounting principles generally accepted in the United States which requires management to make judgments, estimates and assumptions that affect the reported amounts of assets, liabilities, revenue and expenses, and related disclosures. On an ongoing basis, management evaluates its estimates including, but not limited to, those related to revenue recognition, including for deductions from revenues (such as rebates, chargebacks, sales returns and sales allowances) and the period of performance, identification of deliverables and evaluation of milestones with respect to our collaborations , recoverability of inventory, certain accrued liabilities including clinical trial and collaboration liability accruals, and share-based compensation. We base our estimates on historical experience and on various other market-specific and other relevant assumptions that we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates.
Revenue Recognition	Revenue Recognition We recognize revenue from product sales and from license fees, milestones, contingent payments and royalties earned on research, collaboration and license arrangements. See “Note 1 - Organization and Summary of Significant Accounting Policies” to our Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2015 for a description of our revenue recognition policies for product sales discounts and allowances, license and contract revenues under our collaboration agreement with Genentech, Inc. and our Patient Assistance Program. Net Product Revenues We recognize revenue when it is both realized or realizable and earned, meaning persuasive evidence of an arrangement exists, delivery has occurred, title has transferred, the price is fixed or determinable, there are no remaining customer acceptance requirements, and collectability of the resulting receivable is reasonably assured. For product sales in the United States, this generally occurs upon delivery of the product to the specialty pharmacy. For product sales in Europe, this generally occurs when our European distribution partner, Swedish Orphan Biovitrum (“Sobi”), has accepted the product. We sell our product, COMETRIQ, in the United States to a specialty pharmacy that benefits from customer incentives and has a right of return. Prior to 2015, COMETRIQ had limited sales history and we could not reliably estimate expected future returns, discounts and rebates of the product at the time the product was sold to the specialty pharmacy, therefore we recognized revenue when the specialty pharmacy provided the product to a patient based on the fulfillment of a prescription, frequently referred to as the “sell-through” revenue recognition model. We have established sufficient historical experience and data to reasonably estimate expected future returns of the product and the discounts and rebates due to payors at the time of shipment to the specialty pharmacy. Accordingly, beginning in January 2015 we began to recognize revenue upon delivery to our U.S. specialty pharmacy. This approach is frequently referred to as the “sell-in” revenue recognition model. In connection with the change in the timing of recognition of U.S. COMETRIQ sales, we recorded a one-time adjustment to recognize revenue and related costs that had previously been deferred under the “sell-through” revenue recognition model, resulting in the additional recognition of gross product revenues of $2.6 million and a nominal amount of cost of goods sold for the three months ended March 31, 2015 ; there were no such additional amounts recorded during the comparable period in 2016 . We also utilize the “sell-in” revenue recognition model for sales to Sobi for all periods presented. Once Sobi has accepted the product, the product is generally no longer subject to return; therefore, we record revenue at the time Sobi has accepted the product. As described further in “Note 2 - Research and Collaboration Agreements”, we are required to provide Sobi with notice of termination under the terms of our collaboration and license agreement with Ipsen for the commercialization and further development of cabozantinib. Pursuant to our commercialization agreement with Sobi, we expect to repurchase the remaining product on hand from Sobi at the termination of that agreement. During the three months ended March 31, 2016 , we recorded reserves for expected future returns from Sobi and our specialty pharmacy in the United States totaling $0.5 million ; there were no such reserves recorded during the comparable period in 2015 .
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2016-09, Improvements to Employee Share-Based Payment Accounting , ( “ ASU 2016-09”) . ASU 2016-09 is aimed at the simplification of several aspects of the accounting for employee share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. ASU 2016-09 is effective for all interim and annual reporting periods beginning after December 15, 2016. Early adoption is permitted. We are currently evaluating the impact that the adoption of ASU 2016-09 will have on our consolidated financial statements and related disclosures. In April 2015, the FASB issued Accounting Standards Update No. 2015-05, Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement , ( “ ASU 2015-05”) . ASU 2015-05 provides guidance to customers about whether a cloud computing arrangement includes a software license. If a cloud computing arrangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 was effective for all interim and annual reporting periods beginning after December 15, 2015 and therefore we adopted ASU 2015-05 in the three months ended March 31, 2016 on a prospective basis. The adoption of ASU 2015-05 did not have a material impact on our Condensed Consolidated Statements of Operations for the three months ended March 31, 2016 and is not expected to have a material effect on our Consolidated Financial Statements in future periods.

Restructurings (Tables)

Restructurings (Tables)	3 Months Ended
	Mar. 31, 2016
Restructuring Charges [Abstract]
Summary Of Components Of Restructuring Liability	The changes of these liabilities, which related primarily to facility charges during the three months ended March 31, 2016 , are summarized in the following table (in thousands): 2010 Restructurings 2014 Restructuring Total Restructuring liability as of December 31, 2015 $ 4,087 $ 503 $ 4,590 Restructuring charge 87 7 94 Proceeds from sale of assets — 34 34 Cash payments, net (846 ) (305 ) (1,151 ) Other items — (34 ) (34 ) Restructuring liability as of March 31, 2016 $ 3,328 $ 205 $ 3,533

Cash and Investments (Tables)

Cash and Investments (Tables)	3 Months Ended
	Mar. 31, 2016
Investments, Debt and Equity Securities [Abstract]
Schedule of Available-for-Sale Securities	The following tables summarize cash and cash equivalents, investments, and restricted cash and investments by balance sheet line item as of March 31, 2016 and December 31, 2015 (in thousands): March 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash and cash equivalents $ 276,881 $ 1 $ — $ 276,882 Short-term investments 45,179 74 (18 ) 45,235 Long-term investments 82,841 9 82,850 Long-term restricted cash and investments 2,650 — 2,650 Total cash and investments $ 407,551 $ 84 $ (18 ) $ 407,617 December 31, 2015 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Cash and cash equivalents $ 141,634 $ — $ — $ 141,634 Short-term investments 25,484 5 (63 ) 25,426 Long-term investments 83,665 2 (67 ) 83,600 Long-term restricted cash and investments 2,650 — — 2,650 Total cash and investments $ 253,433 $ 7 $ (130 ) $ 253,310
Summary of Cash and Investments by Security Type	The amounts presented exclude cash, but include investments classified as cash equivalents (in thousands): March 31, 2016 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 129,887 $ — $ — $ 129,887 Commercial paper 177,934 1 — 177,935 Corporate bonds 68,297 46 (18 ) 68,325 U.S. Treasury and government sponsored enterprises 29,073 37 — 29,110 Total investments $ 405,191 $ 84 $ (18 ) $ 405,257 December 31, 2015 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value Money market funds $ 72,000 $ — $ — $ 72,000 Commercial paper 78,155 — — 78,155 Corporate bonds 72,205 4 (118 ) 72,091 U.S. Treasury and government sponsored enterprises 28,434 1 (12 ) 28,423 Marketable equity security 16 2 — 18 Total investments $ 250,810 $ 7 $ (130 ) $ 250,687
Summary of Available-for-Sale Securities by Contractual Maturity	The following table summarizes the fair value of securities classified as available-for-sale by contractual maturity as of March 31, 2016 (in thousands): Mature within One Year After One Year through Two Years Fair Value Money market funds $ 129,887 $ — $ 129,887 Commercial paper 177,935 — 177,935 Corporate bonds 66,323 2,002 68,325 U.S. Treasury and government sponsored enterprises 27,860 1,250 29,110 Total investments $ 402,005 $ 3,252 $ 405,257

Inventory (Tables)

Inventory (Tables)	3 Months Ended
	Mar. 31, 2016
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consists of the following (in thousands): March 31, December 31, Raw materials $ 1,032 $ 1,037 Work in process 1,720 2,251 Finished goods 734 583 Total 3,486 3,871 Less: non-current portion included in Other assets (1,014 ) (1,255 ) Inventory $ 2,472 $ 2,616

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2016
Debt Disclosure [Abstract]
Schedule Of Debt	The amortized carrying amount of our debt consists of the following (in thousands): March 31, December 31, Convertible Senior Subordinated Notes due 2019 $ 203,900 $ 198,708 Secured Convertible Notes due 2018 104,756 102,727 Term loan payable 80,000 80,000 Total debt 388,656 381,435 Less: current portion (27,500 ) — Long-term debt $ 361,156 $ 381,435
Summary Of The Liability Component Notes	The following is a summary of the liability component of the 2019 Notes (in thousands): March 31, December 31, Net carrying amount of the liability component $ 203,900 $ 198,708 Unamortized discount of the liability component 83,600 88,792 Face amount of the 2019 Notes $ 287,500 $ 287,500 The debt discount and debt issuance costs will be amortized as interest expense through August 2019. The following is a summary of interest expense for the 2019 Notes (in thousands): Three Months Ended March 31, 2016 2015 Stated coupon interest $ 3,055 $ 3,055 Amortization of debt discount and debt issuance costs 5,191 4,721 Total interest expense $ 8,246 $ 7,776 The following is a summary of interest expense for the Deerfield Notes (in thousands): Three Months Ended March 31, 2016 2015 Stated coupon interest paid in cash $ 1,936 $ 1,479 Amortization of debt discount, debt issuance costs and accrual of interest paid in kind 2,029 2,947 Total interest expense $ 3,965 $ 4,426

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2016
Fair Value Disclosures [Abstract]
Schedule Of Fair Value Of Financial Assets Measured On A Recurring Basis	The amounts presented exclude cash, but include investments classified as cash equivalents (in thousands): March 31, 2016 Level 1 Level 2 Total Money market funds $ 129,887 $ — $ 129,887 Commercial paper — 177,935 177,935 Corporate bonds — 68,325 68,325 U.S. Treasury and government sponsored enterprises — 29,110 29,110 Total financial assets $ 129,887 $ 275,370 $ 405,257 December 31, 2015 Level 1 Level 2 Total Money market funds $ 72,000 $ — $ 72,000 Commercial paper — 78,155 78,155 Corporate bonds — 72,091 72,091 U.S. Treasury and government sponsored enterprises — 28,423 28,423 Marketable equity securities 18 — 18 Total financial assets $ 72,018 $ 178,669 $ 250,687
Schedule Of Estimated Fair Value Of Outstanding Debt	The estimated fair value of our financial instruments that are carried at amortized cost for which it is practicable to determine a fair value was as follows (in thousands) : March 31, 2016 December 31, 2015 Carrying Amount Fair Value Carrying Amount Fair Value 2019 Notes $ 203,900 $ 286,149 $ 198,708 $ 336,260 Deerfield Notes $ 104,756 $ 105,166 $ 102,727 $ 101,096 Term loan payable $ 80,000 $ 79,929 $ 80,000 $ 79,815

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2016
Share-based Compensation [Abstract]
Schedule Of Allocated Employee Stock-Based Compensation Expenses	We recorded and allocated employee stock-based compensation expense for our equity incentive plans and our 2000 Employee Stock Purchase Plan (“ESPP”) as follows (in thousands): Three Months Ended March 31, 2016 2015 Research and development expense $ 5,564 $ 627 Selling, general and administrative expense 5,621 1,033 Total employee stock-based compensation expense $ 11,185 $ 1,660
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	We use the Black-Scholes Merton option pricing model to value our stock options. The weighted average grant-date fair value of our stock options and ESPP purchases was as follows: Three Months Ended March 31, 2016 2015 Stock options $ 2.51 $ 1.35 ESPP $ 2.31 $ 0.70
Schedule Of Fair Value Of Employee Share-Based Payments Awards Estimated Using The Assumptions And Weighted Average Fair Values	The fair value of employee stock option awards and ESPP purchases was estimated using the following assumptions: Stock Options Three Months Ended March 31, 2016 2015 Risk-free interest rate 1.16 % 1.20 % Dividend yield — % — % Volatility 79 % 95 % Expected life 4.3 years 4.5 years Employee Stock Purchase Plan Three Months Ended March 31, 2016 2015 Risk-free interest rate 0.51 % 0.11 % Dividend yield — % — % Volatility 81 % 96 % Expected life 6 months 6 months
Summary Of All Stock Option Activity	A summary of all stock option activity for the three months ended March 31, 2016 is presented below (dollars in thousands , except per share amounts): Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Options outstanding at December 31, 2015 27,425,854 $ 4.22 Granted 2,062,850 $ 4.17 Exercised (21,500 ) $ 1.70 Forfeited (116,788 ) $ 3.26 Options outstanding at March 31, 2016 29,350,416 $ 4.22 4.97 years $ 28,038 Exercisable at March 31, 2016 18,979,572 $ 4.23 4.34 years $ 20,380
Summary Of All RSU Activity	A summary of all restricted stock unit (“RSU”) activity for the three months ended March 31, 2016 is presented below (dollars in thousands , except per share amounts): Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term Aggregate Intrinsic Value Awards outstanding at December 31, 2015 1,002,188 $ 5.16 Awarded 1,996,441 $ 4.23 Released (1,110,549 ) $ 4.25 Forfeited (3,559 ) $ 5.87 Awards outstanding at March 31, 2016 1,884,521 $ 4.71 1.80 years $ 7,632

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2016
Earnings Per Share [Abstract]
Schedule Of Reconciliation Of Basic And Diluted Net Income (Loss) Per Share	The following table sets forth a reconciliation of basic and diluted net loss per share (in thousands, except per share amounts): Three Months Ended March 31, 2016 2015 Numerator: Net loss $ (61,347 ) $ (35,170 ) Denominator: Shares used in computing basic and diluted net loss per share 228,304 195,904 Net loss per share, basic and diluted $ (0.27 ) $ (0.18 )
Schedule Of Potential Shares Of Common Stock Not Included In Computation Of Diluted Net Loss Per Share	The following table sets forth outstanding potentially dilutive shares of common stock that are not included in the computation of diluted net loss per share because, to do so would be anti-dilutive (in thousands): March 31 2016 2015 Convertible Senior Subordinated Notes due 2019 54,118 54,118 Secured Convertible Notes due 2018 33,890 33,890 Outstanding stock options, unvested RSUs and ESPP contributions 31,364 29,591 Warrants 1,000 1,000 Total potentially dilutive shares 120,372 118,599

Concentrations of Credit Risk (

Concentrations of Credit Risk (Tables)	3 Months Ended
	Mar. 31, 2016
Risks and Uncertainties [Abstract]
Schedules of concentration risk	The following table sets forth the percentage of revenues recognized by customer that represent 10% or more of total revenues: Three Months Ended March 31, 2016 2015 Product sales: Diplomat Specialty Pharmacy 55 % 86 % Swedish Orphan Biovitrum 4 % 14 % Collaboration agreements: Merck 32 % — % The following table shows the percentage of revenues earned in the United States and European Union. Three Months Ended March 31, 2016 2015 Percentage of revenues earned in the United States 88 % 86 % Percentage of revenues earned in the European Union 12 % 14 %

Organization and Summary of S26

Organization and Summary of Significant Accounting Policies (Details)	Apr. 25, 2016	Mar. 31, 2016USD ($)segment	Mar. 31, 2015USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Operations [Line Items]
Operating cycle		364 days	371 days
Number of operating segments | segment		1
Net income (loss)		$ (61,347,000)	$ (35,170,000)
Retained earnings (accumulated deficit)		(1,998,388,000)		$ (1,998,388,000)	$ (1,937,041,000)	[1]
Net product revenues		9,099,000	9,388,000	83,400,000
Cash and investments		407,617,000		407,617,000	253,310,000
Cash and investments available for operations		323,300,000		323,300,000
Compensating balance investments		81,600,000		81,600,000
Long-term restricted cash and investments		2,650,000		$ 2,650,000	$ 2,650,000	[1]
Reserve for returns and repurchase of unsold product		500,000	0
“Sell-In” Revenue Recognition Model [Member]
Operations [Line Items]
Net product revenues		$ 0	$ 2,600,000
Minimum [Member]
Operations [Line Items]
Operating cycle		364 days
Maximum [Member]
Operations [Line Items]
Operating cycle		371 days
Subsequent Event [Member]
Operations [Line Items]
Shipping period for newly approved product, upon initial approval	3 days
[1]	The condensed consolidated balance sheet as of December 31, 2015 has been derived from the audited financial statements as of that date.

Research and Collaboration Ag27

Research and Collaboration Agreements (Ipsen Collaboration) (Details)	Feb. 29, 2016USD ($)paymentcountry	Mar. 31, 2016USD ($)	Mar. 31, 2016USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2015USD ($)	[1]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Current portion of deferred revenue		$ 14,371,000	$ 14,371,000		$ 0
Long-term portion of deferred revenue		184,431,000	184,431,000		$ 0
Reserve for returns and repurchase of unsold product			500,000	$ 0
Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront and milestone payments		200,000,000
Eligible payment from collaboration for development and regulatory milestone achievement Under Collaborations Agreement	$ 252,500,000
Maximum amount eligible for commercial milestones under collaborations agreement	$ 525,000,000
Research and development arrangement performed for others, reimbursement for costs incurred (as a percent)	35.00%
License and contract revenue			1,200,000
Current portion of deferred revenue		14,400,000	14,400,000
Long-term portion of deferred revenue		$ 184,400,000	184,400,000
RCC [Member] | Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible payment from collaboration for development and regulatory milestone achievement Under Collaborations Agreement	$ 60,000,000
HCC Filing [Member] | Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible payment from collaboration for development and regulatory milestone achievement Under Collaborations Agreement	10,000,000
HCC Acceptance [Member] | Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Eligible payment from collaboration for development and regulatory milestone achievement Under Collaborations Agreement	$ 40,000,000
EU Country Launch [Member] | Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of payments to be received upon milestone achievement | payment	2
Maximum amount eligible for commercial milestones under collaborations agreement	$ 10,000,000
Number of countries in which entity launches product | country	2
Initial [Member] | Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percent of royalty on net sale	2.00%
Royalty tier	$ 50,000,000
Second [Member] | Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percent of royalty on net sale	12.00%
Royalty tier	$ 100,000,000
Initial and second [Member] | Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Royalty tier	$ 150,000,000
Minimum [Member] | Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percent of royalty on net sale	22.00%
Maximum [Member] | Ipsen [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percent of royalty on net sale	26.00%
Swedish Orphan Biovitrum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Termination fee			2,800,000
Reserve for returns and repurchase of unsold product			$ 400,000
[1]	The condensed consolidated balance sheet as of December 31, 2015 has been derived from the audited financial statements as of that date.

Research and Collaboration Ag28

Research and Collaboration Agreements (Genetech and Other Collaborations) (Details) - USD ($)	1 Months Ended			3 Months Ended
	Nov. 30, 2015	Jan. 31, 2007	Dec. 31, 2006	Mar. 31, 2016	Mar. 31, 2015
Genentech [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront and milestone payments		$ 15,000,000	$ 25,000,000
Profit sharing agreement, percent of total sales force	25.00%
License and contract revenue				$ 100,000	$ 0
Merck [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development milestone payments received under collaborative arrangement				$ 5,000,000
Profit Sharing Tier One [Member] | Genentech [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Profit sharing agreement (as a percent of profits)				50.00%
Profit sharing agreement, profit threshold				$ 200,000,000
Profit Sharing Tier Two [Member] | Genentech [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Profit sharing agreement (as a percent of profits)				30.00%
Profit sharing agreement, profit threshold				$ 400,000,000
Selling, general and administrative expense [Member] | Genentech [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangement, income (loss) from agreement				$ (7,300,000)	$ (3,000,000)

Restructurings (Narrative) (Det

Restructurings (Narrative) (Details) $ in Thousands	3 Months Ended		39 Months Ended
	Mar. 31, 2016USD ($)	Mar. 31, 2015USD ($)	May. 31, 2013restructuring	Dec. 31, 2015USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charge (recovery)	$ 94	$ (431)
Restructuring reserve	3,533			$ 4,590
Expected additional restructuring costs to be incurred	200
Facility Closing [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charge (recovery)		300
Recoveries related to sale of buildings		$ (900)
2010 Restructurings [Member]
Restructuring Cost and Reserve [Line Items]
Number of restructurings implemented | restructuring			5
Restructuring charge (recovery)	87
Restructuring reserve	$ 3,328			$ 4,087

Restructurings (Summary of Comp

Restructurings (Summary of Components of Restructuring Liability) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	$ 4,590
Restructuring charge	94	$ (431)
Proceeds from sale of assets	34
Cash payments, net	(1,151)
Other items	(34)
Restructuring liability, ending balance	3,533
2010 Restructurings [Member]
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	4,087
Restructuring charge	87
Proceeds from sale of assets	0
Cash payments, net	(846)
Other items	0
Restructuring liability, ending balance	3,328
2014 Restructuring [Member]
Restructuring Reserve [Roll Forward]
Restructuring liability, beginning balance	503
Restructuring charge	7
Proceeds from sale of assets	34
Cash payments, net	(305)
Other items	(34)
Restructuring liability, ending balance	$ 205

Cash and Investments (Details)

Cash and Investments (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2016USD ($)accountinvestmentsecurityaffiliate	Mar. 31, 2015USD ($)security	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 407,551,000			$ 253,433,000
Gross Unrealized Gains	84,000			7,000
Gross Unrealized Losses	(18,000)			(130,000)
Fair Value	$ 407,617,000			253,310,000
Debt collateral, number of required investment accounts | account	1
Debt collateral, number of affiliate banks | affiliate	1
Amortized Cost	$ 405,191,000			250,810,000
Gross Unrealized Gains	84,000			7,000
Gross Unrealized Losses	(18,000)			(130,000)
Fair Value	$ 405,257,000			250,687,000
Number of marketable securities sold | security	1	0
Loss on sale of investments, less than	$ 1,000	$ 1,000	$ 0
Number of investments in an unrealized loss position, less than 1 year | investment	19
Unrealized loss position, less than 1 year	$ (18,000)
Unrealized loss position, less than 1 year, fair value	37,900,000
Mature within One Year	402,005,000
After One Year through Two Years	3,252,000
Fair Value	405,257,000			250,687,000
Money market funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	129,887,000			72,000,000
Gross Unrealized Gains	0			0
Gross Unrealized Losses	0			0
Fair Value	129,887,000			72,000,000
Mature within One Year	129,887,000
After One Year through Two Years	0
Fair Value	129,887,000			72,000,000
Commercial paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	177,934,000			78,155,000
Gross Unrealized Gains	1,000			0
Gross Unrealized Losses	0			0
Fair Value	177,935,000			78,155,000
Mature within One Year	177,935,000
After One Year through Two Years	0
Fair Value	177,935,000			78,155,000
Corporate bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	68,297,000			72,205,000
Gross Unrealized Gains	46,000			4,000
Gross Unrealized Losses	(18,000)			(118,000)
Fair Value	68,325,000			72,091,000
Mature within One Year	66,323,000
After One Year through Two Years	2,002,000
Fair Value	68,325,000			72,091,000
U.S. Treasury and government sponsored enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	29,073,000			28,434,000
Gross Unrealized Gains	37,000			1,000
Gross Unrealized Losses	0			(12,000)
Fair Value	29,110,000			28,423,000
Mature within One Year	27,860,000
After One Year through Two Years	1,250,000
Fair Value	29,110,000			28,423,000
Marketable equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost				16,000
Gross Unrealized Gains				2,000
Gross Unrealized Losses				0
Fair Value				18,000
Fair Value				18,000
Silicon Valley Bank Loan And Security Agreement [Member]
Schedule of Available-for-sale Securities [Line Items]
Collateral balance	81,600,000			81,600,000
Cash and cash equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	276,881,000			141,634,000
Gross Unrealized Gains	1,000			0
Gross Unrealized Losses	0			0
Fair Value	276,882,000			141,634,000
Short-term investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	45,179,000			25,484,000
Gross Unrealized Gains	74,000			5,000
Gross Unrealized Losses	(18,000)			(63,000)
Fair Value	45,235,000			25,426,000
Long-term investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	82,841,000			83,665,000
Gross Unrealized Gains	$ 9,000			2,000
Gross Unrealized Losses				(67,000)
Fair Value	$ 82,850,000			83,600,000
Long-term restricted cash and investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,650,000			2,650,000
Gross Unrealized Gains	$ 0			0
Gross Unrealized Losses				0
Fair Value	$ 2,650,000			$ 2,650,000

Inventory (Details)

Inventory (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Inventory Disclosure [Abstract]
Raw materials	$ 1,032,000	$ 1,037,000
Work in process	1,720,000	2,251,000
Finished goods	734,000	583,000
Total	3,486,000	3,871,000
Less: non-current portion included in Other assets	(1,014,000)	(1,255,000)
Inventory	2,472,000	$ 2,616,000	[1]
Inventory Write-down	$ 0
[1]	The condensed consolidated balance sheet as of December 31, 2015 has been derived from the audited financial statements as of that date.

Debt (Schedule Of Debt) (Detail

Debt (Schedule Of Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total debt	$ 388,656	$ 381,435
Less: current portion	(27,500)	0
Long-term debt	361,156	381,435
Senior Subordinated Notes [Member] | 4.25% Convertible Senior Subordinated Notes due August 15, 2019 [Member]
Debt Instrument [Line Items]
Convertible Debt	203,900	198,708
Secured Debt [Member] | Secured Convertible Notes due 2018 [Member]
Debt Instrument [Line Items]
Convertible Debt	104,756	102,727
Term Loan [Member]
Debt Instrument [Line Items]
Term loan payable	$ 80,000	$ 80,000

Debt (Convertible Notes) (Detai

Debt (Convertible Notes) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Aug. 31, 2012
Senior Subordinated Notes [Member] | 4.25% Convertible Senior Subordinated Notes due August 15, 2019 [Member]
Debt Instrument [Line Items]
Net carrying amount of the liability component	$ 203,900,000		$ 198,708,000
Unamortized discount of the liability component	83,600,000		88,792,000
Face amount of the 2019 Notes	287,500,000		287,500,000	$ 287,500,000
Stated coupon interest	3,055,000	$ 3,055,000
Amortization of debt discount and debt issuance costs	5,191,000	4,721,000
Total interest expense	8,246,000	7,776,000
Secured Convertible Notes Due June 2018 [Member] | Deerfield Financing [Member]
Debt Instrument [Line Items]
Net carrying amount of the liability component	105,800,000		$ 103,800,000
Stated coupon interest	1,936,000	1,479,000
Amortization of debt discount and debt issuance costs	2,029,000	2,947,000
Total interest expense	$ 3,965,000	$ 4,426,000

Debt (Narrative) (Details)

Debt (Narrative) (Details) - USD ($)	Jul. 01, 2015	Mar. 31, 2016	Jan. 31, 2016	Jan. 31, 2015	Mar. 31, 2016	Dec. 31, 2015	Aug. 31, 2012
Ipsen [Member]
Debt Instrument [Line Items]
Upfront and milestone payments		$ 200,000,000
Senior Subordinated Notes [Member] | 4.25% Convertible Senior Subordinated Notes due August 15, 2019 [Member]
Debt Instrument [Line Items]
Debt, interest rate (as a percent)							4.25%
Debt, principal amount		287,500,000			$ 287,500,000	$ 287,500,000	$ 287,500,000
Balance of unamortized closing fees and expenses		2,400,000			2,400,000	2,600,000
Convertible debt		203,900,000			203,900,000	198,708,000
Secured Convertible Notes Due June 2018 [Member] | Deerfield Financing [Member]
Debt Instrument [Line Items]
Balance of unamortized closing fees and expenses		600,000			600,000	700,000
Convertible debt		$ 105,800,000			$ 105,800,000	$ 103,800,000
Debt instrument, interest rate, stated percentage after extension option election	15.00%
Annual interest	$ 6,000,000
Debt instrument, effective interest rate (as a percent)		15.30%			15.30%
Percentage of revenue payable under collaborative arrangements			15.00%	15.00%	15.00%
Maximum prepayment amount under collaborative arrangements				$ 27,500,000
Mandatory prepayment under collaborative arrangement					$ 27,500,000
Secured Convertible Notes Due June 2018 [Member] | Deerfield Financing [Member] | Coupon Interest [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage after extension option election		7.50%			7.50%
Secured Convertible Notes Due June 2018 [Member] | Deerfield Financing [Member] | Payment-in-Kind Interest [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage after extension option election		7.50%			7.50%

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule Of Fair Value Of Financial Assets Measured On A Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	$ 405,257	$ 250,687
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	129,887	72,018
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	275,370	178,669
Money market funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	129,887	72,000
Money market funds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	129,887	72,000
Money market funds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0	0
Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	177,935	78,155
Commercial paper [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0	0
Commercial paper [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	177,935	78,155
Corporate bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	68,325	72,091
Corporate bonds [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0	0
Corporate bonds [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	68,325	72,091
U.S. Treasury and government sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	29,110	28,423
U.S. Treasury and government sponsored enterprises [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	0	0
U.S. Treasury and government sponsored enterprises [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	$ 29,110	28,423
Marketable equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets		18
Marketable equity securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets		18
Marketable equity securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets		$ 0

Fair Value Measurements (Sche37

Fair Value Measurements (Schedule of Estimated Fair Value of Outstanding Debt) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Carrying Amount [Member] | Senior Subordinated Notes [Member] | 4.25% Convertible Senior Subordinated Notes due August 15, 2019 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair values of financial instruments	$ 203,900	$ 198,708
Carrying Amount [Member] | Secured Convertible Notes Due June 2018 [Member] | Deerfield Financing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair values of financial instruments	104,756	102,727
Carrying Amount [Member] | Term Loan [Member] | Silicon Valley Bank term loan and Line of Credit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair values of financial instruments	80,000	80,000
Fair Value [Member] | Senior Subordinated Notes [Member] | 4.25% Convertible Senior Subordinated Notes due August 15, 2019 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair values of financial instruments	286,149	336,260
Fair Value [Member] | Secured Convertible Notes Due June 2018 [Member] | Deerfield Financing [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair values of financial instruments	105,166	101,096
Fair Value [Member] | Term Loan [Member] | Silicon Valley Bank term loan and Line of Credit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair values of financial instruments	$ 79,929	$ 79,815

Fair Value Measurements (Sche38

Fair Value Measurements (Schedule of Assumptions Used) (Details)	3 Months Ended
	Mar. 31, 2016
Level 3 [Member] | Warrant liability [Member] | Issued On January 22, 2014 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items]
Fair value inputs, discount rate (as a percent)	16.10%

Stock-Based Compensation (Sched

Stock-Based Compensation (Schedule of Allocated Employee Stock-Based Compensation Expenses) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation expense	$ 11,185	$ 1,660
Research and development expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation expense	5,564	627
Selling, general and administrative expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total employee stock-based compensation expense	$ 5,621	$ 1,033

Stock-Based Compensation (Weigh

Stock-Based Compensation (Weighted Average Grant Date Fair Values) (Details) - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value (in dollars per share)	$ 2.51	$ 1.35
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value (in dollars per share)	$ 2.31	$ 0.70

Stock-Based Compensation (Sch41

Stock-Based Compensation (Schedule of Fair Value of Employee Share-Based Payments Awards Estimated Using the Assumptions) (Details)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.16%	1.20%
Dividend yield	0.00%	0.00%
Volatility	79.00%	95.00%
Expected life	4 years 4 months 6 days	4 years 6 months
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.51%	0.11%
Dividend yield	0.00%	0.00%
Volatility	81.00%	96.00%
Expected life	6 months	6 months

Stock-Based Compensation (Summa

Stock-Based Compensation (Summary of All Stock Option Activity) (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)$ / sharesshares
Shares [Roll Forward]
Options outstanding at beginning of period, Shares | shares	27,425,854
Granted, Shares | shares	2,062,850
Exercised, shares | shares	(21,500)
Forfeited, Shares | shares	(116,788)
Options outstanding at end of period, Shares | shares	29,350,416
Exercisable at end of period, Shares | shares	18,979,572
Weighted Average Exercise Price [Roll Forward]
Options outstanding at beginning of period, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 4.22
Granted, Weighted Average Exercise Price (in dollars per share) | $ / shares	4.17
Exercised, Weighted Average Exercise Price (in dollars per share) | $ / shares	1.70
Forfeited, Weighted Average Exercise Price (in dollars per share) | $ / shares	3.26
Options outstanding at end of period, Weighted Average Exercise Price (in dollars per share) | $ / shares	4.22
Exercisable at end of period, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 4.23
Options outstanding at end of period, Weighted Average Remaining Contractual Term	4 years 11 months 19 days
Exercisable at end of period, Weighted Average Remaining Contractual Term	4 years 4 months 2 days
Options outstanding at end of period, Aggregate Intrinsic Value, in dollars | $	$ 28,038
Exercisable at end of period, Aggregate Intrinsic Value, in dollars | $	$ 20,380

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($) $ in Thousands	Mar. 07, 2016	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense allocated		$ 11,185	$ 1,660
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant		3,439,435
Unrecognized compensation expense		$ 18,000
Unrecognized compensation expense, weighted-average period for recognition (in years)		2 years 9 months 25 days
Performance Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense		$ 300
Number of stock options vested, in shares	2,955,464
Stock-based compensation expense allocated		$ 400		$ 3,300
Additional unvested stock options outstanding, in shares		2,914,839
Grant date fair value		$ 3,700
Performance-based stock options expected to achieve performance objectives		3,400
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense		$ 4,100
Unrecognized compensation expense, weighted-average period for recognition (in years)		2 years 11 months 1 day

Stock-Based Compensation (Sum44

Stock-Based Compensation (Summary of All RSU Activity) (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2016USD ($)$ / sharesshares
Restricted Stock Units (RSUs) [Member]
Shares [Roll Forward]
RSUs outstanding at beginning of period, Shares	1,002,188
Awarded, Shares	1,996,441
Released, Shares	(1,110,549)
Forfeited, Shares	(3,559)
RSUs outstanding at end of period, Shares	1,884,521
Weighted Average Grant DateFair Value [Roll Forward]
RSUs outstanding at beginning of period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares	$ 5.16
Awarded, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares	4.23
Released, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares	4.25
Forfeited, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares	5.87
RSUs outstanding at end of period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares	$ 4.71
RSUs outstanding at end of period, Weighted Average Remaining Contractual Term	1 year 9 months 18 days
RSUs outstanding at end of period, Aggregate Intrinsic Value, in dollars | $	$ 7,632
Bonus_RSU_Grant [Member]
Shares [Roll Forward]
Awarded, Shares	1,072,833
Weighted Average Grant DateFair Value [Roll Forward]
Grant date fair value | $	$ 4,500

Net Loss Per Share (Details)

Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net loss, in dollars	$ (61,347)	$ (35,170)
Shares used in computing basic and diluted net loss per share	228,304	195,904
Net loss per share, basic and diluted, in dollars per share	$ (0.27)	$ (0.18)
Total potentially dilutive shares	120,372	118,599
Convertible debt [Member] | 4.25% Convertible Senior Subordinated Notes due August 15, 2019 [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive shares	54,118	54,118
Convertible debt [Member] | Secured Convertible Notes Due June 2018 [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive shares	33,890	33,890
Outstanding stock options, unvested RSUs and ESPP contributions [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive shares	31,364	29,591
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total potentially dilutive shares	1,000	1,000

Concentrations of Credit Risk46

Concentrations of Credit Risk (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Concentration Risk [Line Items]
Gain (loss) on foreign exchange fluctuations	$ (0.2)	$ 0.2
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Diplomat Specialty Pharmacy [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	40.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Swedish Orphan Biovitrum [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	4.00%
Customer Concentration Risk [Member] | Product Sales [Member] | Diplomat Specialty Pharmacy [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	55.00%	86.00%
Customer Concentration Risk [Member] | Product Sales [Member] | Swedish Orphan Biovitrum [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	4.00%	14.00%
Customer Concentration Risk [Member] | Collaboration Agreements [Member] | Merck [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	32.00%	0.00%
United States [Member] | Geographic Concentration Risk [Member] | Product Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	88.00%	86.00%
European Union [Member] | Geographic Concentration Risk [Member] | Product Sales [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	12.00%	14.00%