United Therapeutics (UTHR) 10-Q 31 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 24, 2018
Document and Entity Information
Entity Registrant Name	UNITED THERAPEUTICS Corp
Entity Central Index Key	1,082,554
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		43,587,178
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 656	$ 705.1
Marketable investments	581.6	222.3
Accounts receivable, no allowance for 2018 and 2017	215.2	297.1
Inventories, net	101	107.9
Other current assets	54.9	115.5
Total current assets	1,608.7	1,447.9
Marketable investments	595.9	502.7
Goodwill and other intangible assets, net	167.7	45.6
Property, plant and equipment, net	665.2	545.7
Deferred tax assets, net	112.9	113.4
Other non-current assets	261.7	224.1
Total assets	3,412.1	2,879.4
Current liabilities:
Accounts payable and accrued expenses	204.8	171.1
Share tracking awards plan	89.7	240.1
Other current liabilities	77.9	33.5
Total current liabilities	372.4	444.7
Line of credit	250	250
Other non-current liabilities	77.7	63.7
Total liabilities	700.1	758.4
Commitments and contingencies
Temporary equity	19.2	19.2
Stockholders' equity:
Common stock, par value $.01, 245,000,000 shares authorized, 70,205,250 and 69,858,840 shares issued, and 43,586,034 and 43,239,624 shares outstanding at September 30, 2018 and December 31, 2017, respectively	0.7	0.7
Additional paid-in capital	1,924	1,854.3
Accumulated other comprehensive loss	(22.2)	(19.6)
Treasury stock, 26,619,216 shares at September 30, 2018 and December 31, 2017	(2,579.2)	(2,579.2)
Retained earnings	3,369.5	2,845.6
Total stockholders' equity	2,692.8	2,101.8
Total liabilities and stockholders' equity	3,412.1	2,879.4
Preferred stock
Stockholders' equity:
Preferred stock, par value $.01, 10,000,000 shares authorized, no shares issued
Series A junior participating preferred stock
Stockholders' equity:
Preferred stock, par value $.01, 10,000,000 shares authorized, no shares issued

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Accounts receivable, allowance (in dollars)	$ 0	$ 0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	245,000,000	245,000,000
Common stock, shares issued	70,205,250	69,858,840
Common stock, shares outstanding	43,586,034	43,239,624
Treasury stock, shares	26,619,216	26,619,216
Preferred stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Series A junior participating preferred stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000	100,000
Preferred stock, shares issued	0	0

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Net product sales	$ 412.7	$ 445.5	$ 1,246.4	$ 1,260.6
Total revenues	412.7	445.5	1,246.4	1,260.6
Operating expenses:
Cost of product sales	51.9	19.5	166.8	52.7
Research and development	101.1	55	219.1	151
Selling, general and administrative	110.1	47.2	186.6	171
Loss contingency				210
Total operating expenses	263.1	121.7	572.5	584.7
Operating income	149.6	323.8	673.9	675.9
Other income (expense):
Interest income	7.9	2.2	19.9	5.7
Interest expense	(4.1)	(3.3)	(9.6)	(5.5)
Other, net	(0.9)	1.1	(4.8)	2
Impairment of investment in privately-held company	(12.4)	(3.1)	(12.4)	(49.6)
Total other expense, net	(9.5)	(3.1)	(6.9)	(47.4)
Income before income taxes	140.1	320.7	667	628.5
Income tax expense	(33.6)	(44.4)	(143.1)	(229.6)
Net income	$ 106.5	$ 276.3	$ 523.9	$ 398.9
Net income per common share:
Basic (in dollars per share)	$ 2.44	$ 6.37	$ 12.04	$ 9
Diluted (in dollars per share)	$ 2.42	$ 6.27	$ 11.91	$ 8.83
Weighted average number of common shares outstanding:
Basic (in shares)	43.6	43.4	43.5	44.3
Diluted (in shares)	44	44.1	44	45.2

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income	$ 106.5	$ 276.3	$ 523.9	$ 398.9
Other comprehensive income:
Foreign currency translation gains				0.2
Defined benefit pension plan:
Actuarial loss arising during period, net of tax				(0.1)
Amortization of actuarial gain and prior service cost included in net periodic pension cost, net of tax	0.4	0.1	1	0.4
Total defined benefit pension plan, net of tax	0.4	0.1	1	0.3
Unrealized loss on available-for-sale securities, net of tax	(0.7)	(0.3)	(3.6)	(0.5)
Other comprehensive (loss) income, net of tax	(0.3)	(0.2)	(2.6)
Comprehensive income	$ 106.2	$ 276.1	$ 521.3	$ 398.9

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 523.9	$ 398.9
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	25.4	23.3
Share-based compensation benefit	(29.2)	(45)
Impairment of investment in privately-held company	12.4	49.6
Loss contingency		210.9
Other	4.4	(9.2)
Changes in operating assets and liabilities:
Accounts receivable	81.9	(37.3)
Inventories	4.2	(17)
Accounts payable and accrued expenses	21.9	37.9
Other assets and liabilities	15.1	(52.1)
Net cash provided by operating activities	660	560
Cash flows from investing activities:
Purchases of property, plant and equipment	(132.6)	(58.5)
Proceeds from sale of property, plant and equipment		8.3
Purchases of held-to-maturity and other investments	(63.4)	(51.8)
Maturities of held-to-maturity investments	53	52.6
Purchases of available-for-sale investments	(618.5)	(452.6)
Sales/maturities of available-for-sale investments	175.2
Purchase of investment in privately-held company	(5)	(55.3)
Consolidation of variable interest entity		0.1
Acquisition, net of cash acquired	(124.1)
Net cash used in investing activities	(715.4)	(557.2)
Cash flows from financing activities:
Proceeds from line of credit	250	250
Repayment of line of credit	(250)
Payments of debt issuance costs	(13.2)	(0.7)
Payments to repurchase common stock		(250)
Proceeds from the exercise of stock options	15.5	38.2
Proceeds from the issuance of stock under employee stock purchase plan	3.9	4
Net cash provided by financing activities	6.2	41.5
Effect of exchange rate changes on cash and cash equivalents	0.1	0.2
Net (decrease) increase in cash and cash equivalents	(49.1)	44.5
Cash and cash equivalents, beginning of period	705.1	1,023
Cash and cash equivalents, end of period	656	1,067.5
Supplemental cash flow information:
Cash paid for interest	6.9	3.8
Cash paid for income taxes	52.1	250.6
Non-cash investing and financing activities:
Non-cash additions to property, plant and equipment	$ 18.2	$ 7.7

Organization and Business Descr

Organization and Business Description	9 Months Ended
	Sep. 30, 2018
Organization and Business Description
Organization and Business Description	1. Organization and Business Description United Therapeutics Corporation is a biotechnology company focused on the development and commercialization of innovative products to address the unmet medical needs of patients with chronic and life-threatening conditions. We have approval from the U.S. Food and Drug Administration (FDA) to market the following therapies: Remodulin ® (treprostinil) Injection (Remodulin), Tyvaso ® (treprostinil) Inhalation Solution (Tyvaso), Adcirca ® (tadalafil) Tablets (Adcirca), Orenitram ® (treprostinil) Extended-Release Tablets (Orenitram) and Unituxin ® (dinutuximab) Injection (Unituxin). Our only significant revenues outside the United States are derived from sales of Remodulin in Europe. As used in these notes to the consolidated financial statements, unless the context otherwise requires, the terms “we”, “us”, “our”, and similar terms refer to United Therapeutics Corporation and its consolidated subsidiaries.

Basis of Presentation

Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Basis of Presentation
Basis of Presentation	2. Basis of Presentation The accompanying unaudited consolidated financial statements have been prepared in accordance with the rules and regulations of the U.S. Securities and Exchange Commission (SEC) for interim financial information. Accordingly, they do not include all of the information required by U.S. generally accepted accounting principles (GAAP) for complete financial statements. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the accompanying notes to the consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2017, as filed with the SEC on February 21, 2018 (our “Annual Report”). In our management’s opinion, the accompanying consolidated financial statements contain all adjustments, including normal, recurring adjustments, necessary to fairly present our financial position as of September 30, 2018 and December 31, 2017, statements of operations and comprehensive income for the three- and nine-month periods ended September 30, 2018 and September 30, 2017 and statements of cash flows for the nine-month periods ended September 30, 2018 and September 30, 2017. Interim results are not necessarily indicative of results for an entire year. Significant Accounting Policies Update Our significant accounting policies are detailed in Note 2— Summary of Significant Accounting Policies to the consolidated financial statements included in our Annual Report. Significant changes to our accounting policies as a result of adopting Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) , are discussed below. Revenue Recognition On January 1, 2018, we adopted Topic 606 using the modified retrospective approach applied to those contracts in effect as of January 1, 2018. Under this transition method, results for reporting periods beginning after January 1, 2018 are presented under the new standard, while prior period amounts are not adjusted and continue to be reported in accordance with our historical accounting under Topic 605, Revenue Recognition . See the Recently Issued Accounting Standards section below for further discussion of the adoption of Topic 606, including the impact on our 2018 financial statements. To determine revenue recognition for contractual arrangements that we determine are within the scope of Topic 606, we perform the following five steps: (i) identify each contract with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to our performance obligations in the contract; and (v) recognize revenue when (or as) we satisfy the relevant performance obligation. We only apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. We generate revenues from the sale of our five commercially approved products: Remodulin, Tyvaso, Orenitram, Unituxin and Adcirca. We recognize revenue when we transfer control of our products to our distributors, as our contracts have a single performance obligation (delivery of our product). Except for Adcirca sales, the performance obligation is generally satisfied when our products are delivered to the distributor’s designated location. We recognize revenue from Adcirca sales upon shipment from an Eli Lilly and Company (Lilly) distribution center. Future revenue from delivery of our products will be based on purchase orders provided to us by our distributors. We are not required to disclose the value of unsatisfied performance obligations as our contracts have a noncancelable duration of one year or less. See Note 12— Segment Information , for information on revenues disaggregated by commercial product, geographic area and customer. Gross-to-Net Deductions As is customary in the pharmaceutical industry, our product sales are recorded net of various forms of gross-to-net deductions. These deductions vary the consideration we are entitled to in exchange for the sale of our products to our distributors, and include reserves for: (1) rebates and chargebacks; (2) prompt payment discounts; (3) allowances for product returns; and (4) distributor fees and other allowances. We estimate these reserves in the same period that we recognize revenue for product sales to distributors. The net product sales amount recognized represents the amount we believe will not be subject to a significant future reversal of revenue. Estimating gross-to-net deductions involves the use of significant assumptions and judgments, as well as information obtained from external sources. For our rebate and chargeback liabilities, in particular, the time lag experienced in the payment of the rebate or chargeback may result in revisions of these accruals in future periods. However, based on our significant history and experience estimating these accruals and our development of these accruals based on the expected value method, we do not believe there will be significant changes to our estimates recorded during the period of sale. For all types of gross-to-net deductions, for the three- and nine-month periods ended September 30, 2018, we recognized an aggregate reduction of our net product sales of $2.1 million and $3.4 million, respectively, related to revenue recognized from product sales in prior periods. These reductions were primarily due to adjustments to accruals for prior periods related to our participation in state Medicaid programs and contracts with commercial payers. Rebates and chargebacks. Allowances for rebates include mandated discounts due to our participation in various government health care programs and contracted discounts with commercial payers. We estimate our rebate liability on a product-by-product basis, considering actual revenue, contractual discount rates, expected utilization under each contract and historical payment experience. We also consider changes in our product pricing and information regarding changes in program regulations and guidelines. Our chargebacks represent contractual discounts payable to distributors for the difference between the invoice price paid to us by the distributor for a particular product and the contracted price that the distributor’s customer pays for that product. Our chargebacks primarily relate to sales of Adcirca. We estimate our chargeback liability on a product-by-product basis, primarily considering historical payment experience. Although we accrue a liability for rebates and chargebacks in the same period the product is sold, third-party reporting and payment of the rebate or chargeback amount occur on a time lag, with the majority of rebates and chargebacks paid within six months from date of sale. Our liability for rebates and chargebacks is included in accounts payable and accrued expenses on our consolidated balance sheets. Prompt payment discounts. We offer prompt pay discounts to many of our distributors, typically for payments made within 30 days. Prompt pay discounts are estimated in the period of sale based on our experience with sales to eligible distributors. Our domestic distributors have routinely taken advantage of these discounts and we expect them to continue to do so. Prompt pay discounts are recorded as a deduction to the accounts receivable balance presented on our consolidated balance sheets. Product returns. The sales terms for Adcirca and Unituxin include return rights that extend throughout the distribution channel. For Adcirca, we recognize an allowance for returns as customers have the right to return expired product for up to 12 months past the product’s expiration date. Returned product is destroyed. Regulatory exclusivity for Adcirca expired in May 2018, and a generic version of Adcirca became available for purchase in the third quarter of 2018. Due to the availability of the generic version, we expect a significant decline in Adcirca demand, which will result in inventory held by distributors and other downstream customers expiring unsold. As a result, we increased our allowance for product returns for Adcirca from $7.2 million as of December 31, 2017 to $23.0 million as of September 30, 2018. We developed our returns liability as of September 30, 2018, based on our estimates of the amount of Adcirca inventory in the downstream channel and the amount of that inventory that will not be dispensed to patients, using forecasted sales and demand estimates. The estimates were developed using reports from our distributors and third-party data, including the historical impact of generic entrants on other branded products that we deemed comparable to Adcirca. For Unituxin, we ship product with shorter expiration dates (generally nine to 14 months after the initial sale), but our historical returns have not been material and we therefore do not record a returns allowance. For sales of our other commercial products, we do not offer our customers a general right of return. We record our allowance for product returns in other current and non-current liabilities on our consolidated balance sheets. Distributor fees and other allowances. Distributor fees include distribution and other service fees paid to certain distributors. These fees are based on contractual amounts or rates applied to purchases of our product or units of service provided in a given period. Our liability for distributor fees is included in accounts payable and accrued expenses on our consolidated balance sheets. Trade Receivables We invoice and receive payment from our customers after we recognize revenue, resulting in receivables from our customers that are presented as accounts receivable on our consolidated balance sheets. Accounts receivable consist of short-term amounts due from our distributors (generally 30 to 90 days) and are stated at the amount we expect to collect. We establish an allowance for doubtful accounts based on our assessment of the collectability of specific distributor accounts. No impairment losses were recognized as of September 30, 2018 and September 30, 2017. Changes in accounts receivable are primarily due to the timing and magnitude of orders of our products, the timing of when control of our products is transferred to our distributors and the timing of cash collections. Adcirca Adcirca is manufactured for us by Lilly and distributed through its pharmaceutical wholesaler network. Specifically, Lilly handles all of the administrative functions associated with the sale of Adcirca on our behalf, including the receipt and processing of customer purchase orders, shipment to customers, and invoicing and collection of customer payments. We recognize sales of Adcirca on a gross basis (net of reserves for gross-to-net deductions) based on our determination that we are acting as a principal due to our control of the product prior to its transfer to our customers. Our control is evidenced by our substantive ownership of product inventory, the fact that we bear all inventory risks, our primary responsibility for the acceptability of the product to our customers, and our ability to influence net product sales through our contracting decisions with commercial payers and participation in governmental-funded programs. Recently Issued Accounting Standards Accounting Standards Adopted During the Period In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09). The new standard supersedes the revenue recognition requirements in Topic 605, Revenue Recognition (Topic 605) , and requires entities to recognize revenue when control of the promised goods or services is transferred to customers. Revenue is recognized at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. We adopted the new standard on January 1, 2018, using the modified retrospective approach, applied only to contracts in effect as of January 1, 2018. Upon adoption, we changed the timing of revenue recognition for sales of Adcirca to recognize revenue when control of Adcirca is transferred to a distributor upon shipment from a Lilly distribution center, which occurs at the time Adcirca is shipped. Previously, we recognized sales of Adcirca when Adcirca was delivered to distributors. This change did not result in an adjustment to amounts previously recognized as revenue under Topic 605 as all shipments had reached the distributor as of December 31, 2017. Overall, adoption of the new standard did not have a material impact on the amounts reported in our financial statements and there were no other significant changes impacting the timing or measurement of our revenue or our business processes and controls. We have included additional disclosures related to our adoption of Topic 606 above, under Revenue Recognition . In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments—Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01), which requires equity investments to be measured at fair value through net income. Equity investments that are accounted for under the equity method are not impacted. ASU 2016-01 provides a new measurement alternative for equity investments without readily determinable fair values. These investments are measured at cost, less any impairment, adjusted for observable price changes. ASU 2016-01 requires separate presentation of the financial assets and liabilities by category and form. ASU 2016-01 should be applied prospectively and is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. We adopted the new standard on January 1, 2018, with no material impact to our financial statements. Effective January 1, 2018, we elected to record our equity investments in privately-held companies that do not have readily determinable fair values using the alternative measurement method. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows—Classification of Certain Cash Receipts and Cash Payments (ASU 2016-15), which reduces existing diversity in the classification of certain cash receipts and cash payments on the statements of cash flows. ASU 2016-15 should be applied retrospectively and is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. We adopted the new standard on January 1, 2018, with no material impact to our financial statements. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes—Intra-Entity Transfers of Assets Other Than Inventory (ASU 2016-16), which requires that an entity recognize the income tax consequences of an intra-entity transfer of assets other than inventory when the transfer occurs. ASU 2016-16 is effective for annual reporting periods beginning after December 15, 2017. We adopted the new standard on January 1, 2018 using a modified retrospective approach, with no material impact to our financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations-Clarifying the Definition of a Business (ASU 2017-01). This update narrows the definition of a business by providing a screen to determine when an integrated set of assets and activities is not a business. The screen specifies that an integrated set of assets and activities is not a business if substantially all of the fair value of the gross assets acquired or disposed of is concentrated in a single asset or a group of similar identifiable assets. ASU 2017-01 should be applied prospectively and is effective for annual reporting periods beginning after December 15, 2017, and for interim periods within those fiscal years. We adopted the new standard on January 1, 2018, with no material impact to our financial statements. In March 2017, the FASB issued ASU No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost (ASU 2017-07), which requires the service cost component to be reported separately from the other components of net pension cost. Service cost will be presented in the same line item as other employer compensation costs within operating expenses. The other components of net pension cost are required to be presented outside of operations and will be presented in “Other, net” on our consolidated statements of operations. Only the service cost component will be eligible for asset capitalization. Companies are required to apply the change in income statement presentation retrospectively, and the change in capitalized benefit cost prospectively. We adopted the new standard on January 1, 2018, with no material impact to our financial statements. Accounting Standards Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (ASU 2016-02), which requires that assets and liabilities arising under leases be recognized on the balance sheet. ASU 2016-02 also requires additional quantitative and qualitative disclosures that provide the amount, timing, and uncertainty of cash flows relating to lease arrangements. ASU 2016-02 is effective for annual reporting periods beginning after December 15, 2018. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842)—Targeted Improvements (ASU 2018-11). ASU 2018-11 allows entities to elect an optional transition method, allowing for application of ASU 2016-02 at the adoption date, with recognition of a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Early adoption and the use of practical expedients to measure the effect of adoption are permitted. We have elected not to early adopt the standard, and therefore we will adopt the standard on January 1, 2019. We have identified all leases involved in the relevant timeframe. We continue to determine if we will elect to use the practical expedients permitted by the guidance and continue to gather data required to comply with the guidance. Based on the work completed to date, we are considering the implications of adopting the new standard, including the discount rate to be used in valuing new and existing leases and all applicable financial statement disclosures required by the new guidance. We are continuing to evaluate the effect of adoption and anticipate that we will recognize additional assets and corresponding liabilities related to our existing leases on our consolidated balance sheet. We are assessing any potential impacts on our internal controls, business processes, and accounting policies related to both the implementation of, and ongoing compliance with, the new guidance. In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment (ASU 2017-04), which simplifies how an entity is required to test goodwill for impairment. A goodwill impairment will be measured by the amount by which a reporting unit’s carrying value exceeds its fair value, with the amount of impairment not to exceed the carrying amount of goodwill. ASU 2017-04 is effective for goodwill impairment tests in fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years, and must be adopted on a prospective basis. Early adoption is permitted. We do not expect the adoption of this guidance to have a material impact on our financial statements. In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (ASU 2018-02). The standard provides financial statement preparers with an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in each period in which the effect (or portion thereof) of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (Tax Reform) is recorded. ASU 2018-02 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. We do not expect the adoption of this guidance to have a material impact on our financial statements. In August 2018, the FASB issued ASU No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Topic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans (ASU 2018-14). The standard modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. Early adoption is permitted. We do not expect the adoption of this guidance to have a material impact on our financial statements.

Acquisition

Acquisition	9 Months Ended
	Sep. 30, 2018
Acquisition
Acquisition	3. Acquisition SteadyMed Merger On April 29, 2018, we entered into an Agreement and Plan of Merger (Merger Agreement) with SteadyMed Ltd. (SteadyMed) and Daniel 24043 Acquisition Corp Ltd., our wholly-owned subsidiary (Merger Sub). The Merger Agreement provides for the merger of Merger Sub with and into SteadyMed (the Merger), with SteadyMed surviving the Merger as our wholly-owned subsidiary. On August 30, 2018, we completed the Merger. At the effective time of the Merger, each SteadyMed ordinary share was converted into the right to receive (i) $4.46 in cash, representing aggregate consideration payable to former holders of SteadyMed securities of approximately $141 million; and (ii) one contingent value right, representing the right to receive $2.63 in cash upon the achievement of 3,000 patients having initiated treatment using SteadyMed’s Trevyent® product on a commercial basis on or before August 30, 2023 (the Milestone). Aggregate contingent consideration of $75.0 million will become payable if the Milestone is achieved. Trevyent is a post-phase III, development-stage drug-device combination product that combines SteadyMed’s two-day, single-use, disposable PatchPump ® technology with treprostinil, for the subcutaneous treatment of pulmonary arterial hypertension (PAH). Following the acquisition, the operating results of SteadyMed have been included in our consolidated financial statements. For the period from the acquisition date through September 30, 2018, SteadyMed contributed revenues and loss before income taxes of zero and $1.7 million, respectively. Preliminary Purchase Price Allocation The Merger meets the definition of a business combination in accordance with ASC 805, Business Combinations , and as such we applied the acquisition method to account for the transaction, which requires, among other things, that assets acquired and liabilities assumed be recognized at their fair values as of the closing date. The aggregate preliminary purchase price noted above was allocated to the major categories of assets acquired and liabilities assumed based upon their estimated fair values at the closing date using primarily Level 2 and Level 3 inputs. These Level 2 and Level 3 valuation inputs include an estimate of future cash flows and discount rates. Additionally, estimated fair values are based, in part, upon third-party valuations of certain assets, including specifically-identified intangible assets. The allocation of the purchase price to the assets acquired and liabilities assumed, including the residual amount allocated to goodwill, is based upon preliminary information and is subject to change within the measurement period (up to one year from the closing date) as additional information concerning final asset and liability valuations is obtained. The primary elements of this preliminary purchase price allocation that are not yet finalized relate to the forecast of future cash flows utilized in the valuation of the acquired in-process research and development intangible asset and the contingent value right as well as our assessment of tax attributes. During the measurement period, if we obtain new information about facts and circumstances that existed as of the closing date that, if known, would have resulted in revised estimated values of those assets or liabilities as of that date, we will revise the preliminary purchase price allocation. The effect of measurement period adjustments on the estimated fair values will be reflected as if the adjustments had been completed on the closing date. The impact of all changes that do not qualify as measurement period adjustments will be included in current period earnings. The following table summarizes the consideration paid for the acquisition and the amounts of the assets acquired and liabilities assumed as of the closing date, which have been allocated on a preliminary basis. Preliminary Purchase Price Allocation Fair Value (in millions) Cash $ Intangible assets: In-process research and development Goodwill (1) Trademark Property, plant and equipment Other assets Total fair value of assets acquired $ Accounts payable and accrued expenses Other liabilities Total fair value of liabilities assumed $ Total purchase price $ (1) We expect the full amount of goodwill to be deductible for income tax purposes over the next 15 years. We determined the fair value of in-process research and development (IPR&D) using the multi-period earnings method under the income approach. This method reflects the present value of the projected cash flows that are expected to be generated by the IPR&D, less charges representing the required return on other assets to sustain those cash flows. We ascribed no value to the contingent value rights based on a probability weighted discounted cash flow model, utilizing probability adjusted expectations for achieving the Milestone. In making this determination we considered expectations regarding the timing and probability of FDA approval of Trevyent, the potential patient population, and estimates of product penetration and uptake by August 30, 2023. As of September 30, 2018, there have been no material changes in assumptions used as of the closing date and, therefore, no changes to the value of the contingent consideration. Acquisition-related costs Costs incurred to complete the Merger and integrate SteadyMed into our business were expensed as incurred and included within selling, general and administrative costs on our consolidated statements of operations. During the three and nine months ended September 30, 2018, we recognized $2.5 million and $5.0 million of acquisition-related costs, respectively. These costs represent transaction costs, legal fees and professional third-party service fees.

Investments

Investments	9 Months Ended
	Sep. 30, 2018
Investments
Investments	4. Investments Available-for-Sale Investments Marketable investments classified as available-for-sale consisted of the following (in millions): As of September 30, 2018 Amortized Gross Fair U.S. government and agency securities $ $ ) $ Corporate notes and bonds ) Total $ $ ) $ Reported under the following captions on our consolidated balance sheet: Current marketable investments Non-current marketable investments Total $ As of December 31, 2017 Amortized Gross Fair U.S. government and agency securities $ $ ) $ Corporate notes and bonds — Total $ $ ) $ Reported under the following captions on our consolidated balance sheet: Cash and cash equivalents $ Current marketable investments Non-current marketable investments Total $ The following table summarizes the contractual maturities of available-for-sale marketable investments (in millions): September 30, 2018 Amortized Fair Due in less than one year $ $ Due in one to three years Total $ $ December 31, 2017 Amortized Fair Due within one year $ $ Due in one to three years Total $ $ Investments in Privately-Held Companies As of September 30, 2018, we maintained non-controlling equity investments in privately-held companies of approximately $176.6 million in the aggregate. Upon adoption of ASU 2016-01 on January 1, 2018, we began to measure these investments using the measurement alternative because the fair values of these investments are not readily determinable. Under this alternative, the investments are measured at cost, less any impairment, adjusted for any observable price changes. During the three- and nine-month periods ended September 30, 2018, we paid zero and $5.0 million, respectively, for an investment in a privately-held company. We include our investments in privately-held companies within other non-current assets on our consolidated balance sheets. These investments are subject to a periodic impairment review and if impaired, the investment is measured and recorded at fair value in accordance with ASC 820, Fair Value Measurements . During the quarter ended September 30, 2018, one of the privately-held companies in which we have invested underwent a significant change in management and a change in business outlook and strategy, all of which triggered our review of the recoverability of our investment in the company. We determined the fair value of our investment as of September 30, 2018 considering an income approach based on the company’s discounted projected cash flows. We corroborated the implied revenue multiples from the income approach with the observed revenue multiples of comparable public companies. We concluded that the fair value of our investment as of September 30, 2018 was lower than its carrying value, resulting in an impairment charge of $12.4 million. As of September 30, 2018, the adjusted carrying value of our investment in this company was $41.1 million. During the quarter ended June 30, 2017, this same privately-held company sought to raise additional funding, which triggered our review of the recoverability of our investment in the company. We determined the non-recurring fair value of our investment as of June 30, 2017 utilizing Level 2 and 3 inputs that considered both (1) an income approach based on the company’s discounted projected cash flows; and (2) a market approach based on the revenue multiples of comparable public companies. We concluded that the fair value of our investment as of June 30, 2017 was lower than its carrying value, resulting in an impairment charge of $46.5 million. As of June 30, 2017, the adjusted carrying value of our investment in this company was $53.5 million. During the quarter ended September 30, 2017, we recorded an impairment charge of $3.1 million for our investment in a different privately-held company. Variable Interest Entity In April 2017, we made a $7.5 million minority investment in a privately-held company. In addition to our investment, we entered into an exclusive license, development and commercialization agreement (the License Agreement) with this company. The License Agreement provides us certain control rights and, as a result, we are required to consolidate the balance sheet and results of operations of this company. The control rights relate to additional research and development funding that we may provide to this company over a period of six years. We are also entitled to representation on a joint development committee that approves the company’s use of funding provided by us. For further details regarding this investment, refer to Note 4— Investments—Variable Interest Entity to the consolidated financial statements included in our Annual Report.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
Fair Value Measurements
Fair Value Measurements	5. Fair Value Measurements We account for certain assets and liabilities at fair value and classify these assets and liabilities within a fair value hierarchy (Level 1, Level 2 or Level 3). Our other current assets and other current liabilities have fair values that approximate their carrying values. Assets and liabilities subject to fair value measurements are as follows (in millions): As of September 30, 2018 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ $ — $ — $ Time deposits (2) — — U.S. government and agency securities (2) — — Corporate debt securities (2) — — Total assets $ $ $ — $ Liabilities Contingent consideration (3) — — Total liabilities $ — $ — $ $ As of December 31, 2017 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ $ — $ — $ Time deposits (2) — — U.S. government and agency securities (2) — — Corporate debt securities (2) — — Total assets $ $ $ — $ Liabilities Contingent consideration (3) — — Total liabilities $ — $ — $ $ (1) Included in cash and cash equivalents on the accompanying consolidated balance sheets. (2) Included in cash equivalents and current and non-current marketable investments on the accompanying consolidated balance sheets. The fair value of these securities is principally measured or corroborated by trade data for identical securities in which related trading activity is not sufficiently frequent to be considered a Level 1 input or comparable securities that are more actively traded. (3) Included in non-current liabilities on the accompanying consolidated balance sheets. The fair value of contingent consideration has been estimated using probability-weighted discounted cash flow models (DCFs). The DCFs incorporate Level 3 inputs including estimated discount rates that we believe market participants would consider relevant in pricing and the projected timing and amount of cash flows, which are estimated and developed, in part, based on the requirements specific to each acquisition agreement. Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable, and accrued expenses approximate fair value because of their short maturities. The fair values of our marketable investments are reported above within the fair value hierarchy. Refer to Note 4 —Investments. The carrying value of our debt is a reasonable estimate of the fair value of the outstanding debt based on the variable interest rate of the debt.

Inventories

Inventories	9 Months Ended
	Sep. 30, 2018
Inventories
Inventories	6. Inventories Inventories are stated at the lower of cost (first-in, first-out method) or net realizable value and consist of the following, net of reserves (in millions): September 30, December 31, Raw materials $ $ Work-in-progress Finished goods Total inventories $ $

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	9 Months Ended
	Sep. 30, 2018
Goodwill and Other Intangible Assets
Goodwill and Other Intangible Assets	7. Goodwill and Other Intangible Assets Goodwill and other intangible assets comprise the following (in millions): As of September 30, 2018 As of December 31, 2017 Gross Accumulated Net Gross Accumulated Net Goodwill $ $ — $ $ $ — $ Other intangible assets: Technology, patents and trade names ) ) In-process research and development — — Total $ $ ) $ $ $ ) $ For more information, refer to Note 3— Acquisition .

Debt

Debt	9 Months Ended
	Sep. 30, 2018
Debt
Debt	8. Debt Unsecured Revolving Credit Facility — 2018 Credit Agreement In June 2018, we entered into a Credit Agreement (the 2018 Credit Agreement) with Wells Fargo Bank, National Association (Wells Fargo), as administrative agent and a swingline lender, and various other lender parties, providing for (i) an unsecured revolving credit facility of up to $1.0 billion; and (ii) a second unsecured revolving credit facility of up to $500.0 million (which facilities may, at our request, be increased by up to $300 million in the aggregate subject to obtaining commitments from existing or new lenders for such increase and other conditions). The facilities will mature five years after the closing date of the 2018 Credit Agreement, subject to the lenders’ ability to extend the maturity date by one year if we request such an extension in accordance with the terms of the 2018 Credit Agreement, up to a maximum of two such extensions. At our option, amounts borrowed under the 2018 Credit Agreement bear interest at either the LIBOR rate or a fluctuating base rate, in each case, plus an applicable margin determined on a quarterly basis based on our consolidated ratio of total indebtedness to EBITDA (as calculated in accordance with the 2018 Credit Agreement). On June 27, 2018, we borrowed $250.0 million under the 2018 Credit Agreement, and used the funds to repay outstanding indebtedness under the 2016 Credit Agreement as discussed below under Unsecured Revolving Credit Facility — 2016 Credit Agreement . The 2018 Credit Agreement contains customary events of default and customary affirmative and negative covenants. As of September 30, 2018, we were in compliance with these covenants. Lung Biotechnology PBC is our only subsidiary that guarantees our obligations under the Credit Agreement though, from time to time, one or more of our other subsidiaries may be required to guarantee our obligations. In connection with the 2018 Credit Agreement, we incurred debt issuance costs of $13.2 million. We capitalized $12.6 million of these costs. As of September 30, 2018, $2.4 million is recorded in other current assets and $9.6 million in other non-current assets on our consolidated balance sheet. These debt issuance costs are being amortized to interest expense over the contractual term of the 2018 Credit Agreement. Unsecured Revolving Credit Facility — 2016 Credit Agreement In January 2016, we entered into a credit agreement (the 2016 Credit Agreement) with Wells Fargo, as administrative agent and a swingline lender, and various other lender parties, providing for an unsecured revolving credit facility of up to $1.0 billion. On June 1, 2017, we borrowed $250.0 million under this facility and used the funds to initiate an accelerated share repurchase program. Refer to Note 10 —Stockholders’ Equity—Share Repurchase. On June 27, 2018, we repaid in full all our obligations under the 2016 Credit Agreement in connection with the termination of the 2016 Credit Agreement and our entry into the 2018 Credit Agreement. There were no penalties associated with the early termination of the 2016 Credit Agreement.

Share-Based Compensation

Share-Based Compensation	9 Months Ended
	Sep. 30, 2018
Share-Based Compensation
Share-Based Compensation	9. Share-Based Compensation As of September 30, 2018, we have two shareholder-approved equity incentive plans: the United Therapeutics Corporation Amended and Restated Equity Incentive Plan (the 1999 Plan) and the United Therapeutics Corporation Amended and Restated 2015 Stock Incentive Plan (the 2015 Plan). The 2015 Plan was approved by our shareholders in June 2015 and provides for the issuance of up to 6,150,000 shares of our common stock pursuant to awards granted under the 2015 Plan. On June 26, 2018, our shareholders approved an amendment and restatement of the 2015 Plan to increase the maximum number of shares of our common stock that may be issued under the 2015 Plan by 2,900,000 shares. As a result of the approval of the 2015 Plan, no further awards have been or will be granted under the 1999 Plan. Currently, we grant equity-based awards including stock options and restricted stock units under the 2015 Plan. Refer to the sections entitled Employee Stock Options and Restricted Stock Units below. We previously issued awards under the United Therapeutics Corporation Share Tracking Awards Plan (2008 STAP) and the United Therapeutics Corporation 2011 Share Tracking Awards Plan (2011 STAP). We refer to the 2008 STAP and the 2011 STAP collectively as the “STAP” and awards granted and/or outstanding under either of these plans as “STAP awards.” Refer to the section entitled Share Tracking Awards Plans below. We discontinued the issuance of STAP awards in June 2015. In 2012, our shareholders approved the United Therapeutics Corporation Employee Stock Purchase Plan (ESPP), which is structured to comply with Section 423 of the Internal Revenue Code. Refer to the section entitled Employee Stock Purchase Plan below. The following table reflects the components of share-based compensation expense (benefit) recognized in our consolidated statements of operations (in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Stock options $ $ $ $ Restricted stock units STAP awards ) ) ) Employee stock purchase plan Total share-based compensation expense (benefit) before tax $ $ ) $ ) $ ) Employee Stock Options We estimate the fair value of stock options using the Black-Scholes-Merton valuation model, which requires us to make certain assumptions that can materially impact the estimation of fair value and related compensation expense. The assumptions used to estimate fair value include the price of our common stock, the expected volatility of our common stock, the risk-free interest rate, the expected term of stock option awards and the expected dividend yield. In March 2017, we began issuing stock options with performance vesting conditions to certain executives. These stock options have vesting conditions tied to the achievement of specified performance criteria, which have target performance levels that span from one to three years. Upon the conclusion of the performance period, the performance level achieved is measured and the ultimate number of shares that may vest is determined. Share-based compensation expense for these awards is recorded ratably over their vesting period, depending on the specific terms of the award and anticipated achievement of the specified performance criteria. During the nine-month period ended September 30, 2018, we granted 0.9 million stock options with performance vesting conditions with a total grant date fair value of $23.7 million based on achievement of target performance levels. During the three- and nine-month periods ended September 30, 2018, we recorded $11.3 million and $29.2 million of share-based compensation expense related to stock options with performance vesting conditions. The table below includes the weighted-average assumptions used to measure the fair value of all stock options (including both stock options with time-based vesting and performance-based vesting conditions) granted during the nine-month periods ended September 30, 2018 and September 30, 2017: September 30, September 30, Expected volatility % % Risk-free interest rate % % Expected term of awards (in years) Expected dividend yield % % A summary of the activity and status of stock options under our equity incentive plans during the nine-month period ended September 30, 2018 is presented below: Number of Weighted- Weighted Aggregate Outstanding at January 1, 2018 $ Granted Exercised ) Forfeited/canceled ) Outstanding at September 30, 2018 $ $ Exercisable at September 30, 2018 $ $ Unvested at September 30, 2018 $ $ The weighted average fair value of a stock option granted during each of the nine-month periods ended September 30, 2018 and September 30, 2017, was $45.02 and $56.07, respectively. These stock options have an aggregate grant date fair value of $44.3 million and $109.8 million, respectively. The total fair value of stock options that vested during the nine-month periods ended September 30, 2018 and September 30, 2017 was $33.9 million and $13.1 million, respectively. Total share-based compensation expense relating to stock options is recorded as follows (in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Cost of product sales $ $ $ $ Research and development Selling, general and administrative Share-based compensation expense before taxes Related income tax benefit ) ) ) ) Share-based compensation expense, net of taxes $ $ $ $ As of September 30, 2018, unrecognized compensation cost was $98.4 million. Unvested outstanding stock options as of September 30, 2018 had a weighted average remaining vesting period of 1.9 years. Stock option exercise data is summarized below (dollars in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Number of options exercised Cash received $ $ $ $ Total intrinsic value of options exercised $ $ $ $ Restricted Stock Units In June 2016, we began issuing restricted stock units to our non-employee directors. In October 2017, we also began issuing restricted stock units to our employees. Each restricted stock unit entitles the recipient to one share of our common stock upon vesting. We measure the fair value of restricted stock units using the stock price on the date of grant. Share-based compensation expense for the restricted stock units is recorded ratably over their vesting period. A summary of the activity with respect to, and status of, restricted stock units under the 2015 Plan during the nine-month period ended September 30, 2018 is presented below: Number of Weighted- Weighted Aggregate Unvested at January 1, 2018 $ Granted Vested ) Forfeited/canceled ) Unvested at September 30, 2018 $ $ Total share-based compensation expense relating to restricted stock units is recorded as follows (in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Cost of product sales $ $ — $ $ — Research and development — — Selling, general and administrative Share-based compensation expense before taxes Related income tax benefit ) ) ) ) Share-based compensation expense, net of taxes $ $ $ $ As of September 30, 2018, unrecognized compensation cost related to the grant of restricted stock units was $17.0 million. Unvested outstanding restricted stock units as of September 30, 2018 had a weighted average remaining vesting period of 2.36 years. Share Tracking Awards Plans STAP awards convey the right to receive in cash an amount equal to the appreciation of our common stock, which is measured as the increase in the closing price of our common stock between the dates of grant and exercise. STAP awards expire on the tenth anniversary of the grant date, and in most cases they vest in equal increments on each anniversary of the grant date over a four-year period. The STAP liability includes vested awards and awards that are expected to vest. We recognize expense for awards that are expected to vest during the vesting period. The aggregate STAP liability balance was $89.7 million and $241.3 million at September 30, 2018 and December 31, 2017, respectively, of which zero and $1.2 million, respectively, have been classified as other non-current liabilities on our consolidated balance sheets based on their vesting terms. Estimating the fair value of STAP awards requires the use of certain inputs that can materially impact the determination of fair value and the amount of compensation expense (benefit) we recognize. Inputs used in estimating fair value include the price of our common stock, the expected volatility of the price of our common stock, the risk-free interest rate, the expected term of STAP awards, and the expected dividend yield. The fair value of the STAP awards is measured at the end of each financial reporting period because the awards are settled in cash. The table below includes the weighted-average assumptions used to measure the fair value of outstanding STAP awards: September 30, September 30, Expected volatility % % Risk-free interest rate % % Expected term of awards (in years) Expected dividend yield — % — % The closing price of our common stock was $127.88 and $117.19 on September 30, 2018 and September 30, 2017, respectively. The closing price of our common stock was $147.95 on December 31, 2017. A summary of the activity and status of STAP awards during the nine-month period ended September 30, 2018 is presented below: Number of Weighted Weighted Aggregate Outstanding at January 1, 2018 $ Granted — — Exercised ) Forfeited ) Outstanding at September 30, 2018 $ $ Exercisable at September 30, 2018 $ $ Unvested at September 30, 2018 $ $ Share-based compensation expense (benefit) recognized in connection with STAP awards is as follows (in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Cost of product sales $ $ ) $ ) $ ) Research and development ) ) ) Selling, general and administrative ) ) ) Share-based compensation expense (benefit) before taxes $ $ ) $ ) $ ) Related income tax (benefit) expense ) Share-based compensation expense (benefit), net of taxes $ $ ) $ ) $ ) Cash paid to settle STAP awards exercised during the nine-month periods ended September 30, 2018 and September 30, 2017 was $71.5 million and $54.1 million, respectively. Employee Stock Purchase Plan In June 2012, our shareholders approved the United Therapeutics Corporation Employee Stock Purchase Plan (ESPP), which is structured to comply with Section 423 of the Internal Revenue Code. The ESPP provides eligible employees with the right to purchase shares of our common stock at a discount through elective accumulated payroll deductions at the end of each offering period. Offering periods, which began in 2012, occur in consecutive six-month periods commencing on September 5th and March 5th of each year. Eligible employees may contribute up to 15 percent of their base salary, subject to certain annual limitations as defined in the ESPP. The purchase price of the shares is equal to the lower of 85 percent of the closing price of our common stock on either the first or last trading day of a given offering period. In addition, the ESPP provides that no eligible employee may purchase more than 4,000 shares during any offering period. The ESPP has a 20-year term and limits the aggregate number of shares that can be issued under the ESPP to 3.0 million.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2018
Stockholders' Equity
Stockholders' Equity	10. Stockholders’ Equity Earnings Per Common Share Basic earnings per common share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the period. Diluted earnings per common share is computed by dividing net income by the weighted average number of shares of common stock outstanding during the period, adjusted for the potential dilutive effect of other securities if such securities were converted or exercised. The components of basic and diluted earnings per common share comprised the following (in millions, except per share amounts): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Numerator: Net income $ $ $ $ Denominator: Weighted average outstanding shares — basic Effect of dilutive securities (1) : Warrants — — — Stock options, restricted stock units and employee stock purchase plan Weighted average shares — diluted (2) Net income per common share: Basic $ $ $ $ Diluted $ $ $ $ Stock options and warrants excluded from calculation (2) (1) Calculated using the treasury stock method. (2) Certain stock options, restricted stock units, and warrants have been excluded from the computation of diluted earnings per share because their impact would be anti-dilutive for the three- and nine-month periods ended September 30, 2018 and September 30, 2017. Share Repurchase In April 2017, our Board of Directors approved a share repurchase program authorizing up to $250.0 million in aggregate repurchases of our common stock. Pursuant to this authorization, in May 2017 we paid $250.0 million to enter into an accelerated share repurchase agreement (ASR) with Citibank, N.A. (Citibank). Pursuant to the terms of the ASR, in June 2017 Citibank delivered to us approximately 1.7 million shares of our common stock, representing the minimum number of shares we were entitled to receive under the ASR. Upon termination of the ASR in September 2017, Citibank delivered to us approximately 0.3 million additional shares of our common stock. The ASR was accounted for as an equity transaction and the shares we repurchased under the ASR were included in treasury stock when the shares were received.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Taxes
Income Taxes	11. Income Taxes Our effective income tax rate (ETR) for the nine months ended September 30, 2018 and September 30, 2017 was 21 percent and 37 percent, respectively. Our ETR for the nine months ended September 30, 2018 decreased, as compared to the same period in 2017, due to the impacts of The Tax Cuts and Jobs Act (Tax Reform), the nondeductible portion of an accrual in the second quarter of 2017 in connection with a civil settlement with the Department of Justice, and a decrease in impairment charges not currently meeting the criteria for tax deductibility. Tax Reform was enacted on December 22, 2017 and has multiple provisions that impact our tax expense. The significant impacts of Tax Reform on our 2018 tax expense include a reduction in the U.S. federal corporate tax rate from 35 percent to 21 percent, a reduction of the Orphan Drug Credit, and the repeal of the Section 199 deduction for domestic manufacturing activities. On December 22, 2017, the SEC staff issued SAB 118 to address the application of U.S. GAAP in situations when a registrant does not have the necessary information available, prepared, or analyzed in reasonable detail to complete the accounting for certain income tax effects of Tax Reform. As a result of changes under Tax Reform, we recognized a provisional amount of $71.0 million of additional tax expense in our consolidated financial statements for the year ended December 31, 2017. The additional tax expense is primarily due to the revaluing of our ending net deferred tax assets at December 31, 2017 because of the reduction in the U.S. corporate income tax rate under Tax Reform. While we have substantially completed our provisional analysis of the income tax effects of Tax Reform, and recorded a reasonable estimate of such effects in our consolidated financial statements for the year ended December 31, 2017, the ultimate impact may differ from these provisional amounts, possibly materially, due to additional U.S. Internal Revenue Service (IRS) guidance and any related analysis and refinement of our calculations. During the nine months ended September 30, 2018, we did not make any material adjustments to the provisional amounts we previously recorded. As of both September 30, 2018 and 2017, our uncertain tax positions were $0.9 million and $0.5 million, respectively. Unrecognized tax benefits as of both September 30, 2018 and 2017, included $0.7 million and $0.3 million, respectively of tax benefits that, if recognized, would impact our ETR. We record interest and penalties related to uncertain tax positions as a component of income tax expense. As of September 30, 2018 and 2017, we have not accrued any material interest expense related to uncertain tax positions. We are unaware of any material positions for which it is reasonably possible that the total amounts of unrecognized tax benefits will significantly increase or decrease within the next twelve months.

Segment Information

Segment Information	9 Months Ended
	Sep. 30, 2018
Segment Information
Segment Information	12. Segment Information We currently operate as one operating segment with a focus on the development and commercialization of products to address the unmet needs of patients with chronic and life-threatening conditions. Our Chief Executive Officer, as our chief operating decision maker, manages and allocates resources to the operations of our company on a consolidated basis. This enables our Chief Executive Officer to assess our overall level of available resources and determine how best to deploy these resources across functions, therapeutic areas, and research and development projects in line with our long-term company-wide strategic goals. Net product sales, cost of product sales and gross profit for each of our commercial products were as follows (in millions): Three Months Ended September 30, 2018 Remodulin Tyvaso Adcirca Orenitram Unituxin Total Net product sales $ $ $ $ $ $ Cost of product sales Gross profit $ $ $ $ $ $ 2017 Net product sales $ $ $ $ $ $ Cost of product sales Gross profit $ $ $ $ $ $ Nine Months Ended September 30, 2018 Remodulin Tyvaso Adcirca Orenitram Unituxin Total Net product sales $ $ $ $ $ $ Cost of product sales Gross profit $ $ $ $ $ $ 2017 Net product sales $ $ $ $ $ $ Cost of product sales Gross profit $ $ $ $ $ $ Geographic revenues are determined based on the country in which our customers (distributors) are located. Total revenues from external customers by geographic area are as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 United States $ $ $ $ Rest-of-World (1) Total $ $ $ $ (1) Primarily Europe. We recorded revenue from two specialty pharmaceutical distributors in the United States comprising 52 percent and 18 percent, respectively, of total revenues during the three-month period ended September 30, 2018, 45 percent and 15 percent, respectively, of total revenues during the three-month period ended September 30, 2017, 50 percent and 17 percent, respectively, of total revenues during the nine-month period ended September 30, 2018, and 47 percent and 15 percent, respectively, of total revenues during the nine-month period ended September 30, 2017. All of our revenues for Adcirca are generated by sales made through Lilly’s pharmaceutical wholesaler network.

Litigation

Litigation	9 Months Ended
	Sep. 30, 2018
Litigation
Litigation	13. Litigation Watson Laboratories, Inc. In June 2015, we received a Paragraph IV certification notice letter from Watson Laboratories, Inc. (Watson) indicating that Watson has submitted an abbreviated new drug application (ANDA) to the FDA to market a generic version of Tyvaso. In its notice letter, Watson states that it intends to market a generic version of Tyvaso before the expiration of U.S. Patent Nos. 6,521,212 and 6,756,033, each of which expires in November 2018; and U.S. Patent No. 8,497,393, which expires in December 2028. Watson’s notice letter states that the ANDA contains a Paragraph IV certification alleging that these patents are not valid, not enforceable, and/or will not be infringed by the commercial manufacture, use or sale of the proposed product described in Watson’s ANDA submission. We responded to the Watson notice letter by filing a lawsuit in July 2015 against Watson in the U.S. District Court for the District of New Jersey alleging infringement of U.S. Patent Nos. 6,521,212, 6,756,033, and 8,497,393. Under the Hatch-Waxman Act, the FDA was automatically precluded from approving Watson’s ANDA for up to 30 months from receipt of Watson’s notice letter (which period expired in December 2017) or until the issuance of a U.S. District Court decision that is adverse to us, whichever occurs first. In June 2016, Watson sent us a second Paragraph IV certification notice letter addressing two new patents, U.S. Patent Nos. 9,339,507 (the ‘507 patent) and 9,358,240 (the ‘240 patent), which expire in March and May 2028, respectively. In June 2016, we filed an amended complaint against Watson asserting these two additional patents. In June 2017, Watson filed petitions with the Patent Trial and Appeal Board (PTAB) of the U.S. Patent and Trademark Office for inter partes review (IPR), seeking to invalidate the ‘507 patent and ‘240 patent. On January 11, 2018, the PTAB issued decisions to institute IPR proceedings with respect to both patents. On August 8, 2018, we entered into a settlement agreement with Watson resolving the ongoing litigation, including the IPR proceedings, concerning Watson’s ANDA for a generic version of Tyvaso. Under the settlement agreement, we granted to Watson a license under our patent rights to manufacture and commercialize the generic version of Tyvaso described in its ANDA filings in the United States beginning on January 1, 2026, although Watson may be permitted to enter the market earlier under certain circumstances. The license included in the settlement agreement does not permit Watson to manufacture a generic version of any other product, such as Remodulin or Orenitram. The settlement agreement does not grant Watson any rights other than those required to launch Watson’s generic version of Tyvaso. The IPR proceedings and District Court litigation have been dismissed.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2018
Subsequent Events
Subsequent Events	14. Subsequent Events License and Collaboration Agreement with MannKind Corporation In September 2018, we entered into a worldwide exclusive license and collaboration agreement with MannKind Corporation (MannKind) for the development and commercialization of a dry powder formulation of treprostinil called Treprostinil Technosphere ® , which is a phase III-ready development-stage product currently being evaluated in clinical trials for the treatment of PAH. The agreement became effective on October 15, 2018, upon expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976. Under the agreement, we are responsible for global development, regulatory and commercial activities relating to Treprostinil Technosphere. We and MannKind will share responsibility for manufacturing clinical supplies and initial commercial supplies of Treprostinil Technosphere. We will manufacture long-term commercial supplies. Under the terms of the agreement, we paid MannKind $45.0 million following the effectiveness of the agreement in October 2018, and we are required to make potential milestone payments of up to $50.0 million upon the achievement of specific development targets. MannKind is also entitled to receive low double-digit royalties on our net sales of the product. In addition, we have the option in our sole discretion to expand the license to include other active ingredients for the treatment of pulmonary hypertension. Each product added pursuant to the option would be subject to the payment to MannKind of up to $40.0 million in additional option exercise and development milestone payments, as well as a low double-digit royalty on our net sales of any such product. We also entered into a research agreement for the conduct of research by MannKind for products outside the scope of the licensing and collaboration agreement. MannKind received an initial payment of $10.0 million in consideration for its performance under the research agreement. The $10.0 million payment is included within research and development costs on our consolidated statements of operations for the three and nine months ended September 30, 2018.

Basis of Presentation (Policies

Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2018
Basis of Presentation.
Revenue Recognition	Revenue Recognition On January 1, 2018, we adopted Topic 606 using the modified retrospective approach applied to those contracts in effect as of January 1, 2018. Under this transition method, results for reporting periods beginning after January 1, 2018 are presented under the new standard, while prior period amounts are not adjusted and continue to be reported in accordance with our historical accounting under Topic 605, Revenue Recognition . See the Recently Issued Accounting Standards section below for further discussion of the adoption of Topic 606, including the impact on our 2018 financial statements. To determine revenue recognition for contractual arrangements that we determine are within the scope of Topic 606, we perform the following five steps: (i) identify each contract with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to our performance obligations in the contract; and (v) recognize revenue when (or as) we satisfy the relevant performance obligation. We only apply the five-step model to contracts when it is probable that we will collect the consideration we are entitled to in exchange for the goods or services we transfer to the customer. We generate revenues from the sale of our five commercially approved products: Remodulin, Tyvaso, Orenitram, Unituxin and Adcirca. We recognize revenue when we transfer control of our products to our distributors, as our contracts have a single performance obligation (delivery of our product). Except for Adcirca sales, the performance obligation is generally satisfied when our products are delivered to the distributor’s designated location. We recognize revenue from Adcirca sales upon shipment from an Eli Lilly and Company (Lilly) distribution center. Future revenue from delivery of our products will be based on purchase orders provided to us by our distributors. We are not required to disclose the value of unsatisfied performance obligations as our contracts have a noncancelable duration of one year or less. See Note 12— Segment Information , for information on revenues disaggregated by commercial product, geographic area and customer. Gross-to-Net Deductions As is customary in the pharmaceutical industry, our product sales are recorded net of various forms of gross-to-net deductions. These deductions vary the consideration we are entitled to in exchange for the sale of our products to our distributors, and include reserves for: (1) rebates and chargebacks; (2) prompt payment discounts; (3) allowances for product returns; and (4) distributor fees and other allowances. We estimate these reserves in the same period that we recognize revenue for product sales to distributors. The net product sales amount recognized represents the amount we believe will not be subject to a significant future reversal of revenue. Estimating gross-to-net deductions involves the use of significant assumptions and judgments, as well as information obtained from external sources. For our rebate and chargeback liabilities, in particular, the time lag experienced in the payment of the rebate or chargeback may result in revisions of these accruals in future periods. However, based on our significant history and experience estimating these accruals and our development of these accruals based on the expected value method, we do not believe there will be significant changes to our estimates recorded during the period of sale. For all types of gross-to-net deductions, for the three- and nine-month periods ended September 30, 2018, we recognized an aggregate reduction of our net product sales of $2.1 million and $3.4 million, respectively, related to revenue recognized from product sales in prior periods. These reductions were primarily due to adjustments to accruals for prior periods related to our participation in state Medicaid programs and contracts with commercial payers. Rebates and chargebacks. Allowances for rebates include mandated discounts due to our participation in various government health care programs and contracted discounts with commercial payers. We estimate our rebate liability on a product-by-product basis, considering actual revenue, contractual discount rates, expected utilization under each contract and historical payment experience. We also consider changes in our product pricing and information regarding changes in program regulations and guidelines. Our chargebacks represent contractual discounts payable to distributors for the difference between the invoice price paid to us by the distributor for a particular product and the contracted price that the distributor’s customer pays for that product. Our chargebacks primarily relate to sales of Adcirca. We estimate our chargeback liability on a product-by-product basis, primarily considering historical payment experience. Although we accrue a liability for rebates and chargebacks in the same period the product is sold, third-party reporting and payment of the rebate or chargeback amount occur on a time lag, with the majority of rebates and chargebacks paid within six months from date of sale. Our liability for rebates and chargebacks is included in accounts payable and accrued expenses on our consolidated balance sheets. Prompt payment discounts. We offer prompt pay discounts to many of our distributors, typically for payments made within 30 days. Prompt pay discounts are estimated in the period of sale based on our experience with sales to eligible distributors. Our domestic distributors have routinely taken advantage of these discounts and we expect them to continue to do so. Prompt pay discounts are recorded as a deduction to the accounts receivable balance presented on our consolidated balance sheets. Product returns. The sales terms for Adcirca and Unituxin include return rights that extend throughout the distribution channel. For Adcirca, we recognize an allowance for returns as customers have the right to return expired product for up to 12 months past the product’s expiration date. Returned product is destroyed. Regulatory exclusivity for Adcirca expired in May 2018, and a generic version of Adcirca became available for purchase in the third quarter of 2018. Due to the availability of the generic version, we expect a significant decline in Adcirca demand, which will result in inventory held by distributors and other downstream customers expiring unsold. As a result, we increased our allowance for product returns for Adcirca from $7.2 million as of December 31, 2017 to $23.0 million as of September 30, 2018. We developed our returns liability as of September 30, 2018, based on our estimates of the amount of Adcirca inventory in the downstream channel and the amount of that inventory that will not be dispensed to patients, using forecasted sales and demand estimates. The estimates were developed using reports from our distributors and third-party data, including the historical impact of generic entrants on other branded products that we deemed comparable to Adcirca. For Unituxin, we ship product with shorter expiration dates (generally nine to 14 months after the initial sale), but our historical returns have not been material and we therefore do not record a returns allowance. For sales of our other commercial products, we do not offer our customers a general right of return. We record our allowance for product returns in other current and non-current liabilities on our consolidated balance sheets. Distributor fees and other allowances. Distributor fees include distribution and other service fees paid to certain distributors. These fees are based on contractual amounts or rates applied to purchases of our product or units of service provided in a given period. Our liability for distributor fees is included in accounts payable and accrued expenses on our consolidated balance sheets. Trade Receivables We invoice and receive payment from our customers after we recognize revenue, resulting in receivables from our customers that are presented as accounts receivable on our consolidated balance sheets. Accounts receivable consist of short-term amounts due from our distributors (generally 30 to 90 days) and are stated at the amount we expect to collect. We establish an allowance for doubtful accounts based on our assessment of the collectability of specific distributor accounts. No impairment losses were recognized as of September 30, 2018 and September 30, 2017. Changes in accounts receivable are primarily due to the timing and magnitude of orders of our products, the timing of when control of our products is transferred to our distributors and the timing of cash collections. Adcirca Adcirca is manufactured for us by Lilly and distributed through its pharmaceutical wholesaler network. Specifically, Lilly handles all of the administrative functions associated with the sale of Adcirca on our behalf, including the receipt and processing of customer purchase orders, shipment to customers, and invoicing and collection of customer payments. We recognize sales of Adcirca on a gross basis (net of reserves for gross-to-net deductions) based on our determination that we are acting as a principal due to our control of the product prior to its transfer to our customers. Our control is evidenced by our substantive ownership of product inventory, the fact that we bear all inventory risks, our primary responsibility for the acceptability of the product to our customers, and our ability to influence net product sales through our contracting decisions with commercial payers and participation in governmental-funded programs.
Recently Issued Accounting Standards	Recently Issued Accounting Standards Accounting Standards Adopted During the Period In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09). The new standard supersedes the revenue recognition requirements in Topic 605, Revenue Recognition (Topic 605) , and requires entities to recognize revenue when control of the promised goods or services is transferred to customers. Revenue is recognized at an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. We adopted the new standard on January 1, 2018, using the modified retrospective approach, applied only to contracts in effect as of January 1, 2018. Upon adoption, we changed the timing of revenue recognition for sales of Adcirca to recognize revenue when control of Adcirca is transferred to a distributor upon shipment from a Lilly distribution center, which occurs at the time Adcirca is shipped. Previously, we recognized sales of Adcirca when Adcirca was delivered to distributors. This change did not result in an adjustment to amounts previously recognized as revenue under Topic 605 as all shipments had reached the distributor as of December 31, 2017. Overall, adoption of the new standard did not have a material impact on the amounts reported in our financial statements and there were no other significant changes impacting the timing or measurement of our revenue or our business processes and controls. We have included additional disclosures related to our adoption of Topic 606 above, under Revenue Recognition . In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments—Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (ASU 2016-01), which requires equity investments to be measured at fair value through net income. Equity investments that are accounted for under the equity method are not impacted. ASU 2016-01 provides a new measurement alternative for equity investments without readily determinable fair values. These investments are measured at cost, less any impairment, adjusted for observable price changes. ASU 2016-01 requires separate presentation of the financial assets and liabilities by category and form. ASU 2016-01 should be applied prospectively and is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. We adopted the new standard on January 1, 2018, with no material impact to our financial statements. Effective January 1, 2018, we elected to record our equity investments in privately-held companies that do not have readily determinable fair values using the alternative measurement method. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows—Classification of Certain Cash Receipts and Cash Payments (ASU 2016-15), which reduces existing diversity in the classification of certain cash receipts and cash payments on the statements of cash flows. ASU 2016-15 should be applied retrospectively and is effective for fiscal years beginning after December 15, 2017, and for interim periods within those fiscal years. We adopted the new standard on January 1, 2018, with no material impact to our financial statements. In October 2016, the FASB issued ASU No. 2016-16, Income Taxes—Intra-Entity Transfers of Assets Other Than Inventory (ASU 2016-16), which requires that an entity recognize the income tax consequences of an intra-entity transfer of assets other than inventory when the transfer occurs. ASU 2016-16 is effective for annual reporting periods beginning after December 15, 2017. We adopted the new standard on January 1, 2018 using a modified retrospective approach, with no material impact to our financial statements. In January 2017, the FASB issued ASU No. 2017-01, Business Combinations-Clarifying the Definition of a Business (ASU 2017-01). This update narrows the definition of a business by providing a screen to determine when an integrated set of assets and activities is not a business. The screen specifies that an integrated set of assets and activities is not a business if substantially all of the fair value of the gross assets acquired or disposed of is concentrated in a single asset or a group of similar identifiable assets. ASU 2017-01 should be applied prospectively and is effective for annual reporting periods beginning after December 15, 2017, and for interim periods within those fiscal years. We adopted the new standard on January 1, 2018, with no material impact to our financial statements. In March 2017, the FASB issued ASU No. 2017-07, Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost (ASU 2017-07), which requires the service cost component to be reported separately from the other components of net pension cost. Service cost will be presented in the same line item as other employer compensation costs within operating expenses. The other components of net pension cost are required to be presented outside of operations and will be presented in “Other, net” on our consolidated statements of operations. Only the service cost component will be eligible for asset capitalization. Companies are required to apply the change in income statement presentation retrospectively, and the change in capitalized benefit cost prospectively. We adopted the new standard on January 1, 2018, with no material impact to our financial statements. Accounting Standards Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (ASU 2016-02), which requires that assets and liabilities arising under leases be recognized on the balance sheet. ASU 2016-02 also requires additional quantitative and qualitative disclosures that provide the amount, timing, and uncertainty of cash flows relating to lease arrangements. ASU 2016-02 is effective for annual reporting periods beginning after December 15, 2018. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842)—Targeted Improvements (ASU 2018-11). ASU 2018-11 allows entities to elect an optional transition method, allowing for application of ASU 2016-02 at the adoption date, with recognition of a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Early adoption and the use of practical expedients to measure the effect of adoption are permitted. We have elected not to early adopt the standard, and therefore we will adopt the standard on January 1, 2019. We have identified all leases involved in the relevant timeframe. We continue to determine if we will elect to use the practical expedients permitted by the guidance and continue to gather data required to comply with the guidance. Based on the work completed to date, we are considering the implications of adopting the new standard, including the discount rate to be used in valuing new and existing leases and all applicable financial statement disclosures required by the new guidance. We are continuing to evaluate the effect of adoption and anticipate that we will recognize additional assets and corresponding liabilities related to our existing leases on our consolidated balance sheet. We are assessing any potential impacts on our internal controls, business processes, and accounting policies related to both the implementation of, and ongoing compliance with, the new guidance. In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other: Simplifying the Test for Goodwill Impairment (ASU 2017-04), which simplifies how an entity is required to test goodwill for impairment. A goodwill impairment will be measured by the amount by which a reporting unit’s carrying value exceeds its fair value, with the amount of impairment not to exceed the carrying amount of goodwill. ASU 2017-04 is effective for goodwill impairment tests in fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years, and must be adopted on a prospective basis. Early adoption is permitted. We do not expect the adoption of this guidance to have a material impact on our financial statements. In February 2018, the FASB issued ASU No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (ASU 2018-02). The standard provides financial statement preparers with an option to reclassify stranded tax effects within accumulated other comprehensive income to retained earnings in each period in which the effect (or portion thereof) of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (Tax Reform) is recorded. ASU 2018-02 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. We do not expect the adoption of this guidance to have a material impact on our financial statements. In August 2018, the FASB issued ASU No. 2018-14, Compensation-Retirement Benefits-Defined Benefit Plans-General (Topic 715-20): Disclosure Framework-Changes to the Disclosure Requirements for Defined Benefit Plans (ASU 2018-14). The standard modifies the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. Early adoption is permitted. We do not expect the adoption of this guidance to have a material impact on our financial statements.

Acquisition (Tables)

Acquisition (Tables)	9 Months Ended
	Sep. 30, 2018
Acquisition
Summary of consideration paid for the acquisition and the amounts of the assets acquired and liabilities assumed	Fair Value (in millions) Cash $ Intangible assets: In-process research and development Goodwill (1) Trademark Property, plant and equipment Other assets Total fair value of assets acquired $ Accounts payable and accrued expenses Other liabilities Total fair value of liabilities assumed $ Total purchase price $ (1) We expect the full amount of goodwill to be deductible for income tax purposes over the next 15 years.

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Investments
Schedule of marketable investments classified as available-for-sale	Marketable investments classified as available-for-sale consisted of the following (in millions): As of September 30, 2018 Amortized Gross Fair U.S. government and agency securities $ $ ) $ Corporate notes and bonds ) Total $ $ ) $ Reported under the following captions on our consolidated balance sheet: Current marketable investments Non-current marketable investments Total $ As of December 31, 2017 Amortized Gross Fair U.S. government and agency securities $ $ ) $ Corporate notes and bonds — Total $ $ ) $ Reported under the following captions on our consolidated balance sheet: Cash and cash equivalents $ Current marketable investments Non-current marketable investments Total $
Summary of the contractual maturities	The following table summarizes the contractual maturities of available-for-sale marketable investments (in millions): September 30, 2018 Amortized Fair Due in less than one year $ $ Due in one to three years Total $ $ December 31, 2017 Amortized Fair Due within one year $ $ Due in one to three years Total $ $

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Measurements
Schedule of assets and liabilities subject to fair value measurements	Assets and liabilities subject to fair value measurements are as follows (in millions): As of September 30, 2018 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ $ — $ — $ Time deposits (2) — — U.S. government and agency securities (2) — — Corporate debt securities (2) — — Total assets $ $ $ — $ Liabilities Contingent consideration (3) — — Total liabilities $ — $ — $ $ As of December 31, 2017 Level 1 Level 2 Level 3 Balance Assets Money market funds (1) $ $ — $ — $ Time deposits (2) — — U.S. government and agency securities (2) — — Corporate debt securities (2) — — Total assets $ $ $ — $ Liabilities Contingent consideration (3) — — Total liabilities $ — $ — $ $ (1) Included in cash and cash equivalents on the accompanying consolidated balance sheets. (2) Included in cash equivalents and current and non-current marketable investments on the accompanying consolidated balance sheets. The fair value of these securities is principally measured or corroborated by trade data for identical securities in which related trading activity is not sufficiently frequent to be considered a Level 1 input or comparable securities that are more actively traded. (3) Included in non-current liabilities on the accompanying consolidated balance sheets. The fair value of contingent consideration has been estimated using probability-weighted discounted cash flow models (DCFs). The DCFs incorporate Level 3 inputs including estimated discount rates that we believe market participants would consider relevant in pricing and the projected timing and amount of cash flows, which are estimated and developed, in part, based on the requirements specific to each acquisition agreement.

Inventories (Tables)

Inventories (Tables)	9 Months Ended
	Sep. 30, 2018
Inventories
Schedule of inventories, net of reserves	Inventories are stated at the lower of cost (first-in, first-out method) or net realizable value and consist of the following, net of reserves (in millions): September 30, December 31, Raw materials $ $ Work-in-progress Finished goods Total inventories $ $

Goodwill and Other Intangible_2

Goodwill and Other Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2018
Goodwill and Other Intangible Assets
Schedule of goodwill and other intangible assets	Goodwill and other intangible assets comprise the following (in millions): As of September 30, 2018 As of December 31, 2017 Gross Accumulated Net Gross Accumulated Net Goodwill $ $ — $ $ $ — $ Other intangible assets: Technology, patents and trade names ) ) In-process research and development — — Total $ $ ) $ $ $ ) $

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Stock options
Share-Based Compensation
Schedule of components of share-based compensation expense (benefit) recognized	The following table reflects the components of share-based compensation expense (benefit) recognized in our consolidated statements of operations (in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Stock options $ $ $ $ Restricted stock units STAP awards ) ) ) Employee stock purchase plan Total share-based compensation expense (benefit) before tax $ $ ) $ ) $ )
Summary of weighted-average assumptions to measure the fair value of stock options	September 30, September 30, Expected volatility % % Risk-free interest rate % % Expected term of awards (in years) Expected dividend yield % %
Schedule of activity and status of stock options	Number of Weighted- Weighted Aggregate Outstanding at January 1, 2018 $ Granted Exercised ) Forfeited/canceled ) Outstanding at September 30, 2018 $ $ Exercisable at September 30, 2018 $ $ Unvested at September 30, 2018 $ $
Schedule of share-based compensation expense (benefit) recognized	Total share-based compensation expense relating to stock options is recorded as follows (in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Cost of product sales $ $ $ $ Research and development Selling, general and administrative Share-based compensation expense before taxes Related income tax benefit ) ) ) ) Share-based compensation expense, net of taxes $ $ $ $
Summary of stock option exercise data	Stock option exercise data is summarized below (dollars in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Number of options exercised Cash received $ $ $ $ Total intrinsic value of options exercised $ $ $ $
Restricted stock units
Share-Based Compensation
Schedule of restricted stock units activity	Number of Weighted- Weighted Aggregate Unvested at January 1, 2018 $ Granted Vested ) Forfeited/canceled ) Unvested at September 30, 2018 $ $
Schedule of share-based compensation expense (benefit) recognized	Total share-based compensation expense relating to restricted stock units is recorded as follows (in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Cost of product sales $ $ — $ $ — Research and development — — Selling, general and administrative Share-based compensation expense before taxes Related income tax benefit ) ) ) ) Share-based compensation expense, net of taxes $ $ $ $
STAP awards
Share-Based Compensation
Schedule of share-based compensation expense (benefit) recognized	Share-based compensation expense (benefit) recognized in connection with STAP awards is as follows (in millions): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Cost of product sales $ $ ) $ ) $ ) Research and development ) ) ) Selling, general and administrative ) ) ) Share-based compensation expense (benefit) before taxes $ $ ) $ ) $ ) Related income tax (benefit) expense ) Share-based compensation expense (benefit), net of taxes $ $ ) $ ) $ )
Schedule of weighted-average assumptions to measure the fair value of outstanding STAP awards	September 30, September 30, Expected volatility % % Risk-free interest rate % % Expected term of awards (in years) Expected dividend yield — % — %
Summary of the activity and status of STAP awards	Number of Weighted Weighted Aggregate Outstanding at January 1, 2018 $ Granted — — Exercised ) Forfeited ) Outstanding at September 30, 2018 $ $ Exercisable at September 30, 2018 $ $ Unvested at September 30, 2018 $ $

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2018
Stockholders' Equity
Schedule of components of basic and diluted earnings per common share	The components of basic and diluted earnings per common share comprised the following (in millions, except per share amounts): Three Months Ended Nine Months Ended 2018 2017 2018 2017 Numerator: Net income $ $ $ $ Denominator: Weighted average outstanding shares — basic Effect of dilutive securities (1) : Warrants — — — Stock options, restricted stock units and employee stock purchase plan Weighted average shares — diluted (2) Net income per common share: Basic $ $ $ $ Diluted $ $ $ $ Stock options and warrants excluded from calculation (2) (1) Calculated using the treasury stock method. (2) Certain stock options, restricted stock units, and warrants have been excluded from the computation of diluted earnings per share because their impact would be anti-dilutive for the three- and nine-month periods ended September 30, 2018 and September 30, 2017.

Segment Information (Tables)

Segment Information (Tables)	9 Months Ended
	Sep. 30, 2018
Segment Information
Schedule of net product sales, cost of product sales and gross profit for each commercial products	Net product sales, cost of product sales and gross profit for each of our commercial products were as follows (in millions): Three Months Ended September 30, 2018 Remodulin Tyvaso Adcirca Orenitram Unituxin Total Net product sales $ $ $ $ $ $ Cost of product sales Gross profit $ $ $ $ $ $ 2017 Net product sales $ $ $ $ $ $ Cost of product sales Gross profit $ $ $ $ $ $ Nine Months Ended September 30, 2018 Remodulin Tyvaso Adcirca Orenitram Unituxin Total Net product sales $ $ $ $ $ $ Cost of product sales Gross profit $ $ $ $ $ $ 2017 Net product sales $ $ $ $ $ $ Cost of product sales Gross profit $ $ $ $ $ $
Schedule of net revenues from external customers by geographic area	Total revenues from external customers by geographic area are as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 United States $ $ $ $ Rest-of-World (1) Total $ $ $ $ (1) Primarily Europe.

Basis of Presentation - (Detail

Basis of Presentation - (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Reduction in net product sales	$ 2.1	$ 3.4
Maximum payment period for prompt pay discounts to distributors		30 days
Expiration period for right to return product		12 months
Impairment losses of trade receivables	$ 0	$ 0		$ 0
Adcirca
Increased allowance for product returns		$ 23	$ 7.2
Minimum
Period of accounts receivable from customers		30 days
Minimum | Unituxin
Expiration period of products from the initial sale date		9 months
Maximum
Period of accounts receivable from customers		90 days
Maximum | Unituxin
Expiration period of products from the initial sale date		14 months

Acquisition - SteadyMed Merger

Acquisition - SteadyMed Merger (Details) $ / shares in Units, $ in Millions	Aug. 30, 2018USD ($)item$ / shares	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)
Acquisition
Acquisition share price | $ / shares	$ 4.46
Aggregate cash consideration paid	$ 141
Acquisition share price contingent upon the achievement of patients having initiated treatment using SteadyMed's Trevyent product | $ / shares	$ 2.63
Number of patients having initiated treatment using SteadyMed's Trevyent product | item	3,000
Aggregate amount of contingent consideration to be paid if the Milestone is achieved	$ 75
Merger contributed revenues		$ 0
Merger contributed loss before income taxes		1.7
Recognized acquisition-related costs			$ 2.5	$ 5
Preliminary Purchase Price Allocation
Cash	17.1
Goodwill	14.6	$ 28.3	$ 28.3	28.3	$ 13.7
Property, plant and equipment	6.2
Other Assets	0.4
Total fair value of assets acquired	145.8
Accounts payable and accrued expenses	4.2
Other liabilities	0.4
Total fair value of liabilities assumed	4.6
Total purchase price	$ 141.2			$ 124.1
Useful life of the goodwill for the income tax purposes	15 years
In-process research and development
Preliminary Purchase Price Allocation
Intangible assets	$ 107.3
Trademark
Preliminary Purchase Price Allocation
Intangible assets	$ 0.2

Investments - Available-for-Sal

Investments - Available-for-Sale (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Marketable investments classified as available-for-sale securities:
Amortized Cost	$ 1,144.5	$ 740.4
Gross Unrealized Losses	(6.6)	(3)
Fair Value	1,137.9	737.4
U.S. government and agency securities
Marketable investments classified as available-for-sale securities:
Amortized Cost	1,072.1	726.5
Gross Unrealized Losses	(6.2)	(3)
Fair Value	1,065.9	723.5
Corporate notes and bonds
Marketable investments classified as available-for-sale securities:
Amortized Cost	72.4	13.9
Gross Unrealized Losses	(0.4)
Fair Value	$ 72	$ 13.9

Investments - Current and Non-c

Investments - Current and Non-current of Available-for-Sale (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Reported under the following captions on our consolidated balance sheet:
Total	$ 1,137.9	$ 737.4
Cash and cash equivalents
Reported under the following captions on our consolidated balance sheet:
Total		41.7
Current marketable investments
Reported under the following captions on our consolidated balance sheet:
Total	544.4	194.6
Non-current marketable investments
Reported under the following captions on our consolidated balance sheet:
Total	$ 593.5	$ 501.1

Investments - Contractual Matur

Investments - Contractual Maturities of Available-for-Sale (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Amortized Cost
Due in less than one year	$ 546.4	$ 236.7
Due in one to three years	598.1	503.7
Total	1,144.5	740.4
Fair Value
Due within one year	544.4	236.3
Due in one to three years	593.5	501.1
Total	$ 1,137.9	$ 737.4

Investments - Investments in Pr

Investments - Investments in Privately-Held Companies (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Investments in Privately-Held Companies
Payments made to acquire investments in privately-held companies				$ 5	$ 55.3
Impairment charges	$ 12.4	$ 3.1		12.4	$ 49.6
Privately-held Companies
Investments in Privately-Held Companies
Investments in Privately-Held Companies	176.6			176.6
Payments made to acquire investments in privately-held companies	0			5
Impairment charges	12.4	$ 3.1	$ 46.5
Adjusted carrying value	$ 41.1		$ 53.5	$ 41.1

Investments - Variable Interest

Investments - Variable Interest Entity (Details) - Variable Interest Entity $ in Millions	1 Months Ended
	Apr. 30, 2017USD ($)
Variable Interest Entity
Funding period for additional research and development	6 years
Privately-held Companies
Variable Interest Entity
Investment purchased during the period	$ 7.5

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Recurring fair value measurements - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Level 1
Assets
Total assets	$ 234.3	$ 217.9
Level 1 | Money market funds
Assets
Total assets	234.3	217.9
Level 2
Assets
Total assets	1,177.5	766.7
Level 2 | Time deposits
Assets
Total assets	35.6	25.2
Level 2 | U.S. government and agency securities
Assets
Total assets	1,065.9	723.5
Level 2 | Corporate debt securities
Assets
Total assets	76	18
Level 3
Liabilities
Contingent consideration	12.8	12.8
Total liabilities	12.8	12.8
Balance
Assets
Total assets	1,411.8	984.6
Liabilities
Contingent consideration	12.8	12.8
Total liabilities	12.8	12.8
Balance | Money market funds
Assets
Total assets	234.3	217.9
Balance | Time deposits
Assets
Total assets	35.6	25.2
Balance | U.S. government and agency securities
Assets
Total assets	1,065.9	723.5
Balance | Corporate debt securities
Assets
Total assets	$ 76	$ 18

Inventories (Details)

Inventories (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Inventories
Raw materials	$ 26	$ 27.9
Work-in-progress	25.6	24.1
Finished goods	49.4	55.9
Total inventories	$ 101	$ 107.9

Goodwill and Other Intangible_3

Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2018	Aug. 30, 2018	Dec. 31, 2017
Goodwill and Other Intangible Assets
Goodwill, Gross	$ 28.3		$ 13.7
Goodwill, Net	28.3	$ 14.6	13.7
Total Goodwill and other intangible assets, Gross	172.7		50.6
Other intangible assets, Accumulated Amortization	(5)		(5)
Total goodwill and other intangible assets, Net	167.7		45.6
Technology, patents and trade names
Goodwill and Other Intangible Assets
Other intangible assets, Gross	6.7		6.5
Other intangible assets, Accumulated Amortization	(5)		(5)
Other intangible assets, Net	1.7		1.5
In-process research and development
Goodwill and Other Intangible Assets
Other intangible assets, Gross	137.7		30.4
Other intangible assets, Net	$ 137.7		$ 30.4

Debt (Details)

Debt (Details) $ in Millions	1 Months Ended	9 Months Ended
	Jun. 30, 2018USD ($)item	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Jun. 27, 2018USD ($)	Jun. 01, 2017USD ($)	Jan. 31, 2016USD ($)
Debt
Debt issuance costs		$ 13.2	$ 0.7
2018 Credit Agreement
Debt
Maximum borrowing capacity	$ 1,000
Debt, maturity term	5 years
Period of extension in maturity	1 year
Number of extensions | item	2
Debt aggregate principal value				$ 250
Debt issuance costs		13.2
Debt issuance costs capitalized		12.6
2018 Credit Agreement | Other current assets
Debt
Debt issuance costs capitalized		2.4
2018 Credit Agreement | Other non-current assets
Debt
Debt issuance costs capitalized		$ 9.6
Second Unsecured Revolving Credit Facility
Debt
Maximum borrowing capacity	$ 500
Increase in borrowing capacity	$ 300
2016 Credit Agreement
Debt
Maximum borrowing capacity						$ 1,000
Debt aggregate principal value					$ 250

Share-Based Compensation - Gene

Share-Based Compensation - General (Details)	Jun. 26, 2018shares	Sep. 30, 2018itemshares
Share-Based Compensation
Number of equity incentive plans | item		2
2015 Plan
Share-Based Compensation
Maximum number of shares authorized to be issued		6,150,000
Amended and Restated 2015 Stock Incentive Plan
Share-Based Compensation
Increase in maximum number of shares authorized to be issued	2,900,000
Amended and Restated Equity Incentive Plan (The 1999 Plan)
Share-Based Compensation
Granted (in shares)		0

Share-Based Compensation - Allo

Share-Based Compensation - Allocation of Compensation Expense (benefit) by Plan (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-Based Compensation
Share-based compensation expense (benefit) before tax	$ 51.4	$ (24)	$ (29.2)	$ (45)
Stock options
Share-Based Compensation
Share-based compensation expense (benefit) before tax	16.6	13.1	44.8	29.9
Restricted stock units
Share-Based Compensation
Share-based compensation expense (benefit) before tax	2.4	0.6	5.3	1.6
STAP awards
Share-Based Compensation
Share-based compensation expense (benefit) before tax	32.2	(38)	(80.1)	(77.5)
Employee stock purchase plan
Share-Based Compensation
Share-based compensation expense (benefit) before tax	$ 0.2	$ 0.3	$ 0.8	$ 1

Share-Based Compensation - Assu

Share-Based Compensation - Assumptions For Stock Options (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-Based Compensation
Share-based compensation expense (benefit) before tax		$ 51.4	$ (24)	$ (29.2)	$ (45)
Stock options
Share-Based Compensation
Granted (in shares)				985,215
Total fair value of employee stock options that vested				$ 33.9	13.1
Share-based compensation expense (benefit) before tax		16.6	$ 13.1	$ 44.8	$ 29.9
Method and assumptions on valuation of stock options
Expected volatility (as a percent)				36.20%	35.70%
Risk-free interest rate (as a percent)				2.70%	2.20%
Expected term of awards (in years)				6 years 3 months 18 days	6 years 1 month 6 days
Expected dividend yield (as a percent)				0.00%	0.00%
Stock options with performance vesting conditions
Share-Based Compensation
Granted (in shares)				900,000
Total fair value of employee stock options that vested				$ 23.7
Share-based compensation expense (benefit) before tax		$ 11.3		$ 29.2
Stock options with performance vesting conditions | Minimum
Share-Based Compensation
Share-based awards, vesting period	1 year
Stock options with performance vesting conditions | Maximum
Share-Based Compensation
Share-based awards, vesting period	3 years

Share-Based Compensation - Stoc

Share-Based Compensation - Stock and Status (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Options
Outstanding at beginning of period (in shares)			5,878,323
Granted (in shares)			985,215
Exercised (in shares)	(4,857)	(40,565)	(287,760)	(428,541)
Forfeited (in shares)			(144,062)
Outstanding at the end of period (in shares)	6,431,716		6,431,716
Exercisable at the end of period (in shares)	3,450,717		3,450,717
Unvested at the end of period (in shares)	2,980,999		2,980,999
Weighted-Average Exercise Price
Outstanding at beginning of period (in dollars per share)			$ 119.61
Granted (in dollars per share)			111.05
Exercised (in dollars per share)			53.82
Forfeited (in dollars per share)			128.87
Outstanding at the end of period (in dollars per share)	$ 121.03		121.03
Exercisable at the end of period (in dollars per share)	113.78		113.78
Unvested at the end of period (in dollars per share)	$ 129.43		$ 129.43
Weighted Average Remaining Contractual Term (in Years)
Outstanding at the end of period (in Years)			7 years
Exercisable at the end of period (in Years)			5 years 8 months 12 days
Unvested at the end of period (in Years)			8 years 7 months 6 days
Aggregate Intrinsic Value
Outstanding at the end of period)	$ 85.4		$ 85.4
Exercisable at the end of period	64.1		64.1
Unvested at the end of period	$ 21.3		$ 21.3
Weighted average grant date fair value of stock options (in dollars per share)			$ 45.02	$ 56.07
Aggregate grant date fair value			$ 44.3	$ 109.8
Total fair value of employee stock options that vested			$ 33.9	$ 13.1

Share-Based Compensation - Shar

Share-Based Compensation - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based compensation expense
Share-based compensation expense (benefit) before tax	$ 51.4	$ (24)	$ (29.2)	$ (45)
Stock options
Share-based compensation expense
Share-based compensation expense (benefit) before tax	16.6	13.1	44.8	29.9
Related income tax benefit	(3.8)	(4.8)	(10.3)	(11)
Share-based compensation expense (benefit), net of tax	12.8	8.3	34.5	18.9
Unrecognized compensation cost	98.4		$ 98.4
Recognition of share-based compensation expense (in years)			1 year 10 months 24 days
Restricted stock units
Share-based compensation expense
Share-based compensation expense (benefit) before tax	2.4	0.6	$ 5.3	1.6
Restricted stock units | 2015 Plan
Share-based compensation expense
Share-based compensation expense (benefit) before tax	2.4	0.6	5.3	1.6
Related income tax benefit	(0.5)	(0.2)	(1.2)	(0.6)
Share-based compensation expense (benefit), net of tax	1.9	0.4	4.1	1
Unrecognized compensation cost	17		$ 17
Recognition of share-based compensation expense (in years)			2 years 4 months 10 days
Cost of product sales | Stock options
Share-based compensation expense
Share-based compensation expense (benefit) before tax	0.2	0.4	$ 0.7	0.9
Cost of product sales | Restricted stock units | 2015 Plan
Share-based compensation expense
Share-based compensation expense (benefit) before tax	0.1		0.3
Research and development | Stock options
Share-based compensation expense
Share-based compensation expense (benefit) before tax	0.9	1	2.8	2.6
Research and development | Restricted stock units | 2015 Plan
Share-based compensation expense
Share-based compensation expense (benefit) before tax	0.5		1.1
Selling, general and administrative | Stock options
Share-based compensation expense
Share-based compensation expense (benefit) before tax	15.5	11.7	41.3	26.4
Selling, general and administrative | Restricted stock units | 2015 Plan
Share-based compensation expense
Share-based compensation expense (benefit) before tax	$ 1.8	$ 0.6	$ 3.9	$ 1.6

Share-Based Compensation - St_2

Share-Based Compensation - Stock Options Exercise Data (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Summary of stock option exercise data
Cash received			$ 15.5	$ 38.2
Stock options
Summary of stock option exercise data
Number of options exercised (in shares)	4,857	40,565	287,760	428,541
Cash received	$ 0.6	$ 1.6	$ 15.5	$ 38.2
Total intrinsic value of options exercised	$ 0.1	$ 3.5	$ 17	$ 27

Share-Based Compensation - Rest

Share-Based Compensation - Restricted Stock Options Activity and Status (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Aggregate Intrinsic Value
Share-based compensation expense (benefit) before tax	$ 51.4	$ (24)	$ (29.2)	$ (45)
Restricted stock units
Aggregate Intrinsic Value
Share-based compensation expense (benefit) before tax	$ 2.4	0.6	$ 5.3	1.6
Restricted stock units | 2015 Plan
Number of Restricted Stock Units
Unvested at beginning of period (in shares)			23,040
Granted (in shares)			191,028
Vested (in shares)			(17,942)
Forfeited/canceled (in shares)			(10,856)
Unvested at the end of period (in shares)	185,270		185,270
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
Unvested at beginning of period (in dollars per share)			$ 128.98
Granted (in dollars per share)			112.20
Vested (in dollars per share)			132.16
Forfeited/canceled (in dollars per share)			111.11
Unvested at the end of period (in dollars per share)	$ 112.42		$ 112.42
Weighted Average Remaining Contractual Term (Years)
Outstanding at the end of period (Years)			9 years 6 months
Aggregate Intrinsic Value
Unvested at the end of period (in dollars)	$ 23.7		$ 23.7
Share-based compensation expense (benefit) before tax	$ 2.4	$ 0.6	$ 5.3	$ 1.6

Share-Based Compensation - STAP

Share-Based Compensation - STAP awards (Details) - STAP awards - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Awards granted
Share-based awards, vesting period	4 years
Aggregate STAP liability	$ 89.7		$ 241.3
Long term portion of STAP liability	$ 0		$ 1.2
Weighted-average assumptions used to measure the fair value of the outstanding STAP awards:
Expected volatility (as a percent)	33.40%	32.80%
Risk-free interest rate (as a percent)	2.50%	1.40%
Expected term of awards (in years)	10 months 24 days	1 year 10 months 24 days
Closing price of common stock (in dollars per share)	$ 127.88	$ 117.19	$ 147.95
Share-based awards activity
Outstanding at January 1, 2018	4,096,394
Exercised (in shares)	(1,060,073)
Forfeited (in shares)	(75,634)
Outstanding at September 30, 2018	2,960,687
Exercisable at September 30, 2018	2,712,516
Unvested at September 30, 2018	248,171
Share awards, Weighted Average Exercise Price
Outstanding at January 1, 2018	$ 95.60
Exercised (in dollars per share)	57.64
Forfeited (in dollars per share)	153.94
Outstanding at September 30, 2018	107.71
Exercisable at September 30, 2018	103.23
Unvested at September 30, 2018	$ 156.61
Share awards, Weighted Average Remaining Contractual Term (in Years)
Outstanding at September 30, 2018	5 years 2 months 12 days
Exercisable at September 30, 2018	5 years 1 month 6 days
Unvested at September 30, 2018	6 years 3 months 18 days
Share awards, Aggregate Intrinsic Value
Outstanding at September 30, 2018	$ 99.8
Exercisable at September 30, 2018	99
Unvested at September 30, 2018	$ 0.8

Share-Based Compensation - Sh_2

Share-Based Compensation - Share Tracking Awards Plans - Benefit recognized (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share based compensation benefit recognized in connection with the STAP
Share-based compensation expense (benefit) before tax	$ 51.4	$ (24)	$ (29.2)	$ (45)
STAP awards
Share based compensation benefit recognized in connection with the STAP
Share-based compensation expense (benefit) before tax	32.2	(38)	(80.1)	(77.5)
Related income tax (benefit) expense	(7.4)	13.9	18.3	28.4
Share-based compensation expense (benefit), net of tax	24.8	(24.1)	(61.8)	(49.1)
Cash payments on awards exercised during the period			71.5	54.1
Cost of product sales | STAP awards
Share based compensation benefit recognized in connection with the STAP
Share-based compensation expense (benefit) before tax	2	(2.1)	(4)	(4.7)
Research and development | STAP awards
Share based compensation benefit recognized in connection with the STAP
Share-based compensation expense (benefit) before tax	6.8	(8.2)	(15.2)	(16.9)
Selling, general and administrative | STAP awards
Share based compensation benefit recognized in connection with the STAP
Share-based compensation expense (benefit) before tax	$ 23.4	$ (27.7)	$ (60.9)	$ (55.9)

Share-Based Compensation - Empl

Share-Based Compensation - Employee Stock Purchase Plan (Details) - Employee stock purchase plan	1 Months Ended
	Jun. 30, 2012shares
Share-based compensation expense
Maximum percentage of compensation employees may contribute for ESPP (in percentage)	15.00%
Percentage of the lower of the fair market value of common stock on the first or last trading day of a given offering period (in percentage)	85.00%
Maximum number of shares each eligible employees may purchase in any given offering period (in shares)	4,000
Term of ESPP (in years)	20 years
Maximum number of shares authorized to be issued (in shares)	3,000,000

Stockholders' Equity - Earning

Stockholders' Equity - Earning Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator:
Net income	$ 106.5	$ 276.3	$ 523.9	$ 398.9
Denominator:
Weighted average outstanding shares - basic (in shares)	43.6	43.4	43.5	44.3
Effect of dilutive securities:
Warrants (in shares)				0.1
Stock options, restricted stock units and employee stock purchase plan (in shares)	0.4	0.7	0.5	0.8
Weighted average shares - diluted (in shares)	44	44.1	44	45.2
Net income per common share:
Basic (in dollars per share)	$ 2.44	$ 6.37	$ 12.04	$ 9
Diluted (in dollars per share)	$ 2.42	$ 6.27	$ 11.91	$ 8.83
Stock options and warrants excluded from calculation (in shares)	4.5	3.7	4.6	3.1

Stockholders' Equity - Share Re

Stockholders' Equity - Share Repurchase (Details) - USD ($) shares in Millions, $ in Millions	1 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	May 31, 2017	Apr. 30, 2017
Share Repurchase
Authorized aggregate repurchases of common stock				$ 250
May 2017 Accelerated Share Repurchase Agreement
Share Repurchase
Payment for cost of accelerated share repurchase agreement entered			$ 250
Repurchased shares of common stock		1.7
Repurchased additional shares of common stock	0.3

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Income Taxes
Effective income tax rate (as a percent)	21.00%	37.00%
Corporate tax rate (as a percent)	21.00%		35.00%
Recognized provisional amount of additional tax expenses			$ 71
Uncertain tax positions	$ 0.9	$ 0.5
Positions of uncertain tax, if realized, would impact the effective tax rate	$ 0.7	$ 0.3

Segment Information - General (

Segment Information - General (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)segment	Sep. 30, 2017USD ($)
Net product sales, cost of product sales and gross profit by product
Net product sales	$ 412.7	$ 445.5	$ 1,246.4	$ 1,260.6
Cost of product sales	51.9	19.5	166.8	52.7
Gross profit	360.8	426	$ 1,079.6	1,207.9
Segment disclosures
Number of operating segments | segment			1
Remodulin
Net product sales, cost of product sales and gross profit by product
Net product sales	153.6	187.3	$ 439.9	490.8
Cost of product sales	4.4	4	10.8	9.9
Gross profit	149.2	183.3	429.1	480.9
Tyvaso
Net product sales, cost of product sales and gross profit by product
Net product sales	107.8	88.9	308.3	280.5
Cost of product sales	6.9	2.2	14.3	7.9
Gross profit	100.9	86.7	294	272.6
Adcirca
Net product sales, cost of product sales and gross profit by product
Net product sales	74.6	99.8	282	300.4
Cost of product sales	32.5	5.6	121.9	16.9
Gross profit	42.1	94.2	160.1	283.5
Orenitram
Net product sales, cost of product sales and gross profit by product
Net product sales	53.8	52.5	155.5	137.8
Cost of product sales	3.9	3.9	9.9	10.7
Gross profit	49.9	48.6	145.6	127.1
Unituxin
Net product sales, cost of product sales and gross profit by product
Net product sales	22.9	17	60.7	51.1
Cost of product sales	4.2	3.8	9.9	7.3
Gross profit	$ 18.7	$ 13.2	$ 50.8	$ 43.8

Segment Information - Geographi

Segment Information - Geographic Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues from external customers by geographic area
Total revenues	$ 412.7	$ 445.5	$ 1,246.4	$ 1,260.6
United States
Revenues from external customers by geographic area
Total revenues	389	385.5	1,177.1	1,133
Rest-of-World
Revenues from external customers by geographic area
Total revenues	$ 23.7	$ 60	$ 69.3	$ 127.6

Segment Information - Concentra

Segment Information - Concentration Risk (Details) - item	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Information
Number of distributors			2
Net revenues | Customer concentration | Customer one
Segment Information
Concentration risk, percentage	52.00%	45.00%	50.00%	47.00%
Net revenues | Customer concentration | Customer two
Segment Information
Concentration risk, percentage	18.00%	15.00%	17.00%	15.00%

Litigation (Details)

Litigation (Details) - Pending Litigation - Watson Laboratories Inc.	9 Months Ended
	Sep. 30, 2018patent
Litigation
Maximum period for which the FDA is automatically precluded from approving ANDA	30 months
Number of additional patents being addressed in litigation	2

Subsequent Events (Details)

Subsequent Events (Details) - License and Collaboration Agreement with MannKind Corporation - Subsequent Events - USD ($) $ in Millions	Oct. 15, 2018	Oct. 31, 2018
Subsequent Events
Amount of consideration paid		$ 45
Amount of potential milestone payments	$ 50
Amount to be paid in additional option exercise and development milestone payments	40
Consideration paid under the research agreement	10
Amount included in research and development costs	$ 10