Elanco Animal Health (ELAN) 10-K 20 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 18, 2019
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Registrant Name	Elanco Animal Health Inc.
Entity Central Index Key	1,739,104
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well Known Seasoned Issuer	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Public Float	$ 0
Entity Common Stock, Shares Outstanding		365,643,911

Consolidated and Combined State

Consolidated and Combined Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenue	$ 3,066.8	$ 2,889	$ 2,913.5
Costs, expenses and other:
Cost of sales	1,573.8	1,493.9	1,409
Research and development	246.6	251.7	265.8
Marketing, selling and administrative	735.2	779.8	784.8
Amortization of intangible assets	197.4	221.2	170.7
Asset impairments, restructuring and other special charges (Note 7)	128.8	375.1	308.4
Interest expense, net of capitalized interest	29.6	0	0
Other (income) expense, net	41.3	(0.1)	(2.8)
Costs, expenses and other	2,952.7	3,121.6	2,935.9
Income (loss) before income taxes	114.1	(232.6)	(22.4)
Income tax expense	27.6	78.1	25.5
Net income (loss)	$ 86.5	$ (310.7)	$ (47.9)
Earnings (loss) per share:
Basic and diluted (usd per share)	$ 0.28	$ (1.06)	$ (0.16)
Weighted average shares outstanding:
Basic and diluted (in shares)	313.7	293.3	293.3

Consolidated and Combined Sta_2

Consolidated and Combined Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 86.5	$ (310.7)	$ (47.9)
Other comprehensive income (loss):
Change in foreign currency translation gains (losses)	(47.1)	210.1	(230.7)
Change in defined benefit pension and retiree health benefit plans, net of taxes	25.4	(9.8)	(4.3)
Other comprehensive income (loss), net of taxes	(21.7)	200.3	(235)
Comprehensive income (loss)	$ 64.8	$ (110.4)	$ (282.9)

Consolidated and Combined Balan

Consolidated and Combined Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 474.8	$ 323.4
Accounts receivable, net of allowances of $8.4 (2018) and $9.8 (2017)	651.8	567.4
Other receivables	57.6	34.5
Inventories (Note 8)	1,004.1	1,062.3
Prepaid expenses and other	113.9	136.1
Restricted cash (Note 19)	202.7	0
Total current assets	2,504.9	2,123.7
Noncurrent Assets
Investments (Note 10)	15.3	12.3
Goodwill (Note 11)	2,958	2,969.2
Other intangibles, net (Note 11)	2,453	2,672.8
Other noncurrent assets	103.1	242
Property and equipment, net (Note 12)	922.4	920.3
Total assets	8,956.7	8,940.3
Current Liabilities
Accounts payable	205.2	203.8
Employee compensation	98.9	89.3
Sales rebates and discounts	169.9	165.5
Current portion of long term debt	29	0
Other current liabilities	199	184.5
Payable to Lilly (Note 19)	268.7	0
Total current liabilities	970.7	643.1
Noncurrent Liabilities
Long-term debt (Note 9)	2,443.3	0
Accrued retirement benefits (Note 17)	109.1	139
Deferred taxes (Note 14)	114.6	251.9
Other noncurrent liabilities	121.5	126
Total liabilities	3,759.2	1,160
Commitments and Contingencies (Note 15)
Equity
Net parent company investment	0	8,036.9
Common stock, no par value, 5,000,000,000 shares authorized 365,643,911 shares issued and outstanding as of December 31, 2018	0	0
Additional paid-in capital	5,403.3	0
Retained earnings	16.4	0
Accumulated other comprehensive loss	(222.2)	(256.6)
Total equity	5,197.5	7,780.3
Total liabilities and equity	$ 8,956.7	$ 8,940.3

Consolidated and Combined Bal_2

Consolidated and Combined Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Receivables, Net, Current [Abstract]
Accounts receivable, allowances	$ 8.4	$ 9.8
Common stock, shares authorized	5,000,000,000
Common stock, shares issued	365,643,911
Common stock, shares outstanding	365,643,911

Consolidated and Combined Sta_3

Consolidated and Combined Statement of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash Flows from Operating Activities
Net income (loss)	$ 86.5	$ (310.7)	$ (47.9)
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation and amortization	296	318.4	254.4
Change in deferred income taxes	(60.7)	(13.4)	(5.9)
Stock-based compensation expense	26	25	20.4
Asset impairment charges	120.5	110.6	98.3
Gain on sale of assets	(0.8)	(19.6)	0
Other non-cash operating activities, net	49	10	6
Other changes in operating assets and liabilities, net of acquisitions and divestitures:
Receivables	(122)	48.4	(80.7)
Inventories	(20.1)	(39)	(89.1)
Other assets	(3.2)	52.5	(36.7)
Accounts payable and other liabilities	116.1	(8.4)	37.1
Net Cash Provided by Operating Activities	487.3	173.8	155.9
Cash Flows from Investing Activities
Purchases of property and equipment	(134.5)	(98.6)	(110.3)
Disposals of property and equipment	9.4	37.6	7.4
Cash paid for acquisitions, net of cash acquired	0	(882.1)	(45)
Other investing activities, net	(1.9)	(21.5)	(34.2)
Net Cash Used for Investing Activities	(127)	(964.6)	(182.1)
Cash Flows from Financing Activities
Proceeds from issuance of long-term debt (Note 9)	2,500	0	0
Repayments of borrowings	(7.5)	0	0
Proceeds from issuance of common stock (Note 1)	1,659.7	0	0
Debt issuance costs	(24.5)	0	0
Consideration paid to Lilly in connection with the Separation (Note 1)	(3,991.3)	0	0
Other financing activities, net	(17.2)	(0.8)	0
Other net transactions with Lilly	(154.4)	848.3	(149.6)
Net Cash Provided by (Used for) Financing Activities	(35.2)	847.5	(149.6)
Effect of exchange rate changes on cash and cash equivalents	29	7.9	(26)
Net increase in cash, cash equivalents and restricted cash	354.1	64.6	(201.8)
Cash, cash equivalents and restricted cash at beginning of period	323.4	258.8	460.6
Cash, cash equivalents and restricted cash at end of period	677.5	323.4	258.8
Cash, cash equivalents and restricted cash at end of period	$ 323.4	$ 258.8	$ 460.6

Consolidated and Combined Sta_4

Consolidated and Combined Statements of Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Net Parent Company Investment	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Foreign Currency Translation	Defined Benefit Pension and Retiree Health Benefit Plans
Balance at beginning of period (in shares) at Dec. 31, 2015		293.3
Balance at beginning of period at Dec. 31, 2015	$ 7,429.5	$ 0	$ 0	$ 7,651.4	$ 0	$ (221.9)	$ (206.6)	$ (15.3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(47.9)			(47.9)
Other comprehensive income (loss), net of tax	(235)					(235)	(230.7)	(4.3)
Transfers (to)/from Lilly, net	(129.2)			(129.2)
Balance at end of period (in shares) at Dec. 31, 2016		293.3
Balance at end of period at Dec. 31, 2016	7,017.4	$ 0	0	7,474.3	0	(456.9)	(437.3)	(19.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(310.7)			(310.7)
Other comprehensive income (loss), net of tax	200.3					200.3	210.1	(9.8)
Transfers (to)/from Lilly, net	873.3			873.3
Balance at end of period (in shares) at Dec. 31, 2017		293.3
Balance at end of period at Dec. 31, 2017	7,780.3	$ 0	0	8,036.9	0	(256.6)	(227.2)	(29.4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	86.5			70.1	16.4
Other comprehensive income (loss), net of tax	(21.7)					(21.7)	(47.1)	25.4
Transfers (to)/from Lilly, net	(226.3)			(226.3)
Separation adjustments	99.6			43.5		56.1	56.1
Issuance of common stock (in shares)		72.3
Issuance of common stock	1,659.7		1,659.7
Consideration to Lilly in connection with the Separation	(4,194.9)		(4,194.9)
Reclassification of net parent company investment	0		7,923.9	(7,923.9)
Shared base compensation	1.8		1.8
Capital contribution from Lilly	12.8		12.8
Balance at end of period (in shares) at Dec. 31, 2018		365.6
Balance at end of period at Dec. 31, 2018	$ 5,197.5	$ 0	$ 5,403.3	$ 0	$ 16.4	$ (222.2)	$ (218.2)	$ (4)

Nature of Business and Organiza

Nature of Business and Organization	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business and Organization	Nature of Business and Organization Nature of Business Elanco Animal Health Incorporated (Elanco Parent) and its subsidiaries (collectively, Elanco, the Company, we, us or our) was formed as a wholly-owned subsidiary of Eli Lilly and Company (Lilly). Elanco is a global animal health company that innovates, develops, manufactures and markets products for companion and food animals. We offer a diverse portfolio of more than 125 brands to veterinarians and food animal producers in more than 90 countries. Organization Elanco Parent was formed in 2018, as a wholly-owned subsidiary of Lilly, to serve as the ultimate parent company of substantially all of the animal health businesses of Lilly. On September 24, 2018, Elanco Parent completed an initial public offering resulting in the issuance of 72.3 million shares of its common stock (including shares issued pursuant to the underwriters’ option to purchase additional shares), which represents 19.8% of the outstanding shares, at $24 per share (IPO) for a total net proceeds, after underwriting discounts and commissions, of $1.7 billion . In connection with the completion of the IPO, through a series of equity and other transactions, Lilly transferred to Elanco Parent the animal health businesses that form its business going forward. In exchange Elanco Parent has paid, or will pay, to Lilly approximately $4.2 billion , which includes the net proceeds from the IPO, the net proceeds from the debt offering completed by Elanco Parent in August 2018 and the term loan facility entered into by Elanco Parent in September 2018 (see Note 9). As of December 31, 2018, Elanco Parent has paid Lilly $4.0 billion with the remaining purchase price reflected in Payable to Lilly on the balance sheet. These transactions are collectively referred to herein as the Separation.

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated and combined financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP). The accounts of all wholly-owned and majority-owned subsidiaries are included in the consolidated financial statements. All intercompany balances and transactions have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses, and related disclosures at the date of the financial statements and during the reporting period. Actual results could differ from those estimates. We issued our financial statements by filing with the Securities and Exchange Commission and have evaluated subsequent events up to the time of the filing. During the period ended December 31, 2018, certain combined balance sheet amounts related to the prior year have been revised to correct the sales rebates and discounts liability, which did not correctly reflect an accrual for rebates related to product held in the wholesalers' pipeline. In accordance with Securities and Exchange Commission Staff Accounting Bulletin No. 99, Materiality , and Accounting Standards Codification (ASC) 250, Presentation of Financial Statements , we assessed the materiality of this correction and concluded that the accrual for the rebate related to product held in the wholesalers' pipeline was not material to prior periods, and therefore, amendments of previously filed reports are not required. As such, in accordance with ASC 250, we revised the previously reported combined balance sheet and combined statements of equity. The adjustment, which originates in periods prior to those presented, resulted in a $10.5 million increase as of December 31, 2017 in the accrual for sales rebates and discounts of $155.0 million , total current liabilities of $632.6 million and total liabilities of $1,149.5 million . In addition, previously reported amounts at December 31, 2017 and December 31, 2016 of net parent company investment of $8,047.4 million and $7,484.8 million , respectively, and total equity of $7,790.8 million and $7,027.9 million , respectively, have been reduced by $10.5 million to reflect the correction above. For the periods after separation, the financial statements are prepared on a consolidated basis and reflect the results of operations, comprehensive income, financial position, equity and cash flows resulting from our operations as an independent company. For periods prior to the Separation, our financial statements are combined, have been prepared on a standalone basis, and are derived from Lilly's consolidated financial statements and accounting records. The consolidated and combined financial statements reflect the financial position, results of operations and cash flows related to the animal health businesses that were transferred to Elanco Parent and are prepared in conformity with GAAP. The combined financial statements include the attribution of certain assets and liabilities that historically have been held at the Lilly corporate level but which are specifically identifiable or attributable to the businesses that have been transferred to Elanco Parent. All intercompany transactions and accounts within Elanco have been eliminated. All transactions between us and Lilly are considered to be effectively settled in the combined financial statements at the time the intercompany transaction is recorded. The total net effect of the settlement of these intercompany transactions is reflected in the combined statements of cash flows as a financing activity and in the combined balance sheets as net parent company investment. Prior to the separation, these combined financial statements include an allocation of expenses related to certain Lilly corporate functions, including executive oversight, treasury, legal, finance, human resources, tax, internal audit, financial reporting, information technology and investor relations, prior to IPO. These expenses have been allocated to us based on direct usage or benefit where specifically identifiable, with the remainder allocated primarily on a pro rata basis of revenue, headcount and other measures. We consider the expenses methodology and results to be reasonable for all periods presented. However, the allocations may not be indicative of the actual expense that would have been incurred had we operated as an independent, publicly traded company for the periods presented. It is impractical to estimate what the standalone costs of Elanco would have been in the historical periods. After the separation, a TSA between Lilly and Elanco went into effect. Under the terms of the TSA, we will be able to use Lilly Services for a fixed term established on a service-by-service basis. We are paying Lilly mutually agreed upon fees for the Lilly Services provided under the TSA. Our consolidated and combined financial statements reflect the charges for Lilly Services after the IPO. See Note 19 for additional details. The income tax amounts in the combined financial statements have been calculated based on a separate return methodology and presented as if our operations were separate taxpayers in the respective jurisdictions. We file income tax returns in the United States (U.S.) federal jurisdiction and various state, local and non-U.S. jurisdictions. Certain of these income tax returns are filed on a consolidated or combined basis with Eli Lilly and Company and/or its subsidiaries. Lilly maintains various benefit and combined stock-based compensation plans at a corporate level and other benefit plans at a country level. Our employees participate in such programs and the portion of the cost of those plans related to our employees is included in our financial statements. However, the consolidated and combined balance sheets do not include any equity issued related to stock-based compensation plans or any net benefit plan obligations unless the benefit plan covers only our dedicated employees or where the legal obligation associated with the benefit plan will transfer to Elanco. Prior to Separation, the equity balance in the combined financial statements represents the excess of total assets over liabilities, including intercompany balances between us and Lilly (net parent company investment) and accumulated other comprehensive loss. Net parent company investment is primarily impacted by contributions from Lilly which are the result of treasury activities and net funding provided by or distributed to Lilly. See Note 19 for further information.

Impact of Separation

Impact of Separation	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
Impact of Separation	Impact of Separation In connection with the Separation, we issued $2.0 billion aggregate principal amount of senior notes in a private placement, and we also entered into a $750.0 million senior unsecured revolving credit facility and $500.0 million senior unsecured term credit facility. See Note 9 for further information. In connection with the Separation, we entered into various agreements with Lilly, including a master separation agreement. In connection with the terms of the Separation, there were certain assets and liabilities included in the pre-Separation balance sheet that were retained by Lilly and there were certain assets not included in the pre-Separation balance sheet that were transferred to us. The cumulative adjustment to the historical balance sheet increased net assets and total equity by approximately $99.6 million . The impact on net assets primarily represent the elimination of certain income tax assets and liabilities and the contribution of additional assets. On February 8, 2019, we filed a Registration Statement on Form S-4 with the SEC in connection with Lilly’s proposed exchange offer, whereby Lilly shareholders can exchange shares of Lilly common stock for shares of our common stock owned by Lilly (exchange offer). Immediately before the commencement of the exchange offer, Lilly owned 293,290,000 shares of our common stock, representing 80.2% of our outstanding common stock. If the exchange offer is not fully subscribed, Lilly intends, from time to time, to complete subsequent exchange offers and/or a pro rata spin-off of its remaining interest in Elanco Parent.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Revenue recognition We recognize revenue from sales of products at the time title of goods passes to the buyer and the buyer assumes the risks and rewards of ownership. Provisions for returns, discounts and rebates are established in the same period the related sales are recognized. For arrangements with contract manufacturing organizations (CMO), we recognize revenue over time or at a point in time depending on its evaluation of when the customer obtains control of the promised goods or service. Revenue is recognized over time when we are creating or enhancing an asset that the customer controls as the asset is created or enhanced or our performance does not create an asset with an alternative use and we have an enforceable right to payment for performance completed. Research and development expenses and acquired in-process research and development Research and development expenses include the following: • Research and development costs, which are expensed as incurred. • Milestone payment obligations incurred prior to regulatory approval of the product, which are accrued when the event requiring payment of the milestone occurs. • Acquired in-process research and development (IPR&D) expense, which includes the initial costs of IPR&D projects, acquired directly in a transaction other than a business combination that do not have an alternative future use. Foreign Currency Translation Operations in our subsidiaries outside the United States (U.S.) are recorded in the functional currency of each subsidiary which is determined by a review of the environment where each subsidiary primarily generates and expends cash. The results of operations for our subsidiaries outside the U.S. are translated from functional currencies into U.S. dollars using the weighted average currency rate for the period. Assets and liabilities are translated using the period end exchange rates. The U.S. dollar effects that arise from translating the net assets of these subsidiaries are recorded in other comprehensive income (loss). Other significant accounting policies Our other significant accounting policies are described in the remaining appropriate notes to the combined financial statements. Implementation of New Financial Accounting Pronouncements The following table provides a brief description of accounting standards that were effective January 1, 2018 and were adopted on that date: Standard Description Effect on the financial statements or other significant matters Accounting Standards Update 2014-09 and various other related updates, Revenue from Contracts with Customers This standard replaced existing revenue recognition standards and requires entities to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. An entity can apply the new revenue standard retrospectively to each prior reporting period presented or with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. We applied the latter approach. Application of the new standard to applicable contracts had no impact to net parent company investment as of January 1, 2018. Disclosures required by the new standard are included in Note 5. Accounting Standards Update 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory This standard requires entities to recognize the income tax consequences of intra-entity transfers of assets other than inventory at the time of transfer. This standard requires a modified retrospective approach to adoption. Upon adoption, the cumulative effect of applying the standard resulted in a decrease to net parent company investment of approximately $0.3 million. Adoption of this standard did not result in a material change in net income for the twelve months ended December 31, 2018. Accounting Standards Update 2017-07, Compensation-Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This standard was issued to improve the transparency and comparability among organizations by requiring entities to separate their net periodic pension cost and net periodic postretirement benefit cost into a service cost component and other components. Previously, the costs of the other components along with the service cost component were classified based upon the function of the employee. This standard requires entities to classify the service cost component in the same financial statement line item or items as other compensation costs arising from services rendered by pertinent employees. The other components of net benefit cost are now presented separately from the line items that include the service cost component. When applicable, the service cost component is now the only component eligible for capitalization. An entity should apply the new standard retrospectively for the classification of the service cost and other components and prospectively for the capitalization of the service cost component. Upon adoption of this standard, pension and postretirement benefit cost components other than service costs are presented in other (income) expense, net. Retrospective application was not material to the combined statement of operations for the twelve months ended December 31, 2017. We do not expect application of the new standard to have a material impact on an ongoing basis. Accounting Standards Update 2017-12, Derivatives and Hedging This standard amends the hedge accounting recognition and presentation requirements and is intended to better align hedge accounting with companies' risk management strategies. This standard eliminates the requirements to separately measure and report hedge ineffectiveness and generally requires that the entire change in fair value of a hedging instrument be presented in the same income statement line item as the respective hedged item. The standard also modifies certain disclosure requirements. We elected to early adopt this guidance as of January 1, 2018. There were no hedging contracts in effect as of the date of adoption. We do not expect application of the new standard to have a material impact on an ongoing basis. The following table provides a brief description of the accounting standard that has not yet been adopted and could have a material effect on the consolidated financial statements: Standard Description Effective Date Effect on the financial statements or other significant matters Accounting Standards Update 2016-02, Leases This standard was issued to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities, including leases classified as operating leases under current GAAP, on the balance sheet and requiring additional disclosures about leasing arrangements. An entity can apply the new leases standard retrospectively to each prior reporting period presented or with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. We plan to use the latter approach. This standard is effective January 1, 2019, with early adoption permitted. We intend to adopt this standard on that date. We expect to record a right-of-use asset and lease liability for operating leases of approximately $75-95 million on our consolidated balance sheet on January 1, 2019. Our accounting for capital leases will remain substantially unchanged. This standard will not have a material impact on our consolidated statement of operations.

Revenue

Revenue	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	Revenue Effective January 1, 2018, we adopted Accounting Standards Update 2014-09, Revenue from Contracts with Customers (ASU 2014-09) and other related updates. The new standard has been applied to contracts for which performance had not been completed as of the date of adoption. Revenue presented for periods prior to 2018 were accounted for under previous standards and has not been adjusted. Revenue and net income for the year ended December 31, 2018 does not differ materially from amounts that would have resulted from application of the previous standards. Product Sales We recognize revenue primarily from product sales to customers. Revenue from sales of products is recognized at the point where the customer obtains control of the goods and we satisfy our performance obligation, which generally is at the time we ship the product to the customer. Payment terms differ by jurisdiction and customer, but payment terms in most of our major jurisdictions typically range from 30 to 100 days from date of shipment. Revenue for our product sales has not been adjusted for the effects of a financing component as we expect, at contract inception, that the period between when we transfer control of the product and when we receive payment will be one year or less. Any exceptions are either not material or we collect interest for payments made after the due date. Provisions for rebates and discounts, and returns are established in the same period the related sales are recognized. We generally, ship product shortly after orders are received; therefore, we generally only have a few days of orders received but not yet shipped at the end of any reporting period. Shipping and handling activities are considered to be fulfillment activities and are not considered to be a separate performance obligation. We exclude from the measurement of the transaction price all taxes assessed by a governmental authority that are imposed on our sales of product and collected from a customer. Significant judgments must be made in determining the transaction price for sales of products related to anticipated rebates and discounts, and returns. The following describe the most significant of these judgments: Sales Rebates and Discounts - Background and Uncertainties • Most of our products are sold to wholesale distributors. We initially invoice our customers contractual list prices. Contracts with direct and indirect customers may provide for various rebates and discounts that may differ in each contract. As a consequence, to determine the appropriate transaction price for our product sales at the time we recognize a sale to a direct customer, we must estimate any rebates or discounts that ultimately will be due to the direct customer and other customers in the distribution chain under the terms of our contracts. Significant judgments are required in making these estimates. • The rebate and discount amounts are recorded as a deduction to arrive at our net product sales. We estimate these accruals using an expected value approach. • In determining the appropriate accrual amount, we consider our historical experience with similar incentives programs and current sales data to estimate the impact of such programs on revenue and continually monitor the impact of this experience and adjust as necessary. Although we accrue a liability for rebates related to these programs at the time the sale is recorded, the rebate related to that sale is typically paid up to six months after rebate or incentive period expires. Because of this time lag, in any particular period rebate adjustments may incorporate revisions of accruals for several periods. Our sales rebates and discounts are based on specific agreements and the majority relate to sales in the U.S. As of December 31, 2018 and 2017, liability for sales rebates and discounts in the U.S. represents approximately 70% and 69% , respectively, of our total liability with the next largest country representing approximately 8% of our total liability for 2018 and 2017. The following table summarizes the activity in the sales rebates and discounts liability in the U.S.: Year Ended December 31, 2018 2017 Beginning balance $ 114.8 $ 116.1 Reduction of revenue 221.0 236.1 Payments (217.3 ) (237.4 ) Ending balance $ 118.5 $ 114.8 Adjustments to revenue recognized as a result of changes in estimates for the judgments described above during the year ended December 31, 2018 for product shipped in previous periods were not material. Sales Returns - Background and Uncertainties • We estimate a reserve for future product returns related to product sales using an expected value approach. This estimate is based on several factors, including: local returns policies and practices; returns as a percentage of revenue; an understanding of the reasons for past returns; estimated shelf life by product; and estimate of the amount of time between shipment and return. Adjustments to the returns reserve have been and may in the future be required based on revised estimates to our assumptions, which would have an impact on our consolidated results of operations. We record the return amounts as a deduction to arrive at our net product sales. • Actual product returns have been approximately 1% of net revenue for the year ended December 31, 2018 and 2017 and have not fluctuated significantly as a percentage of revenue. Disaggregation of Revenue The following table summarizes our revenue disaggregated by product category for the years ended December 31: 2018 2017 2016 Companion Animal Disease Prevention $ 804.6 $ 660.2 $ 628.4 Companion Animal Therapeutics 283.1 260.8 255.6 Food Animal Future Protein & Health 711.2 649.2 630.8 Food Animal Ruminants Swine 1,174.0 1,175.0 1,309.2 Other 93.9 143.8 89.5 Total Revenue $ 3,066.8 $ 2,889.0 $ 2,913.5

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions	Acquisitions During 2017 and 2016, we completed the acquisitions of BIVIVP and certain rights to Aratana Therapeutics, Inc.'s (Aratana) Galliprant®, respectively. These transactions were accounted for as business combinations under the acquisition method of accounting. Under this method, the assets acquired and liabilities assumed were recorded at their respective fair values as of the acquisition date in our combined financial statements. The determination of estimated fair value required management to make significant estimates and assumptions. The excess of the purchase price over the fair value of the acquired net assets, where applicable, has been recorded as goodwill. The results of operations of these acquisitions are included in our consolidated and combined financial statements from the dates of acquisition. Boehringer Ingelheim Vetmedica, Inc. Vaccine Portfolio Acquisition On January 3, 2017, we acquired BIVIVP in a cash transaction for $882.1 million . Under the terms of the agreement, we acquired a manufacturing and research and development site, a U.S. vaccine portfolio including vaccines used for the treatment of bordetella, Lyme disease, rabies and parvovirus, among others. The following table summarizes the amounts recognized for assets acquired and liabilities assumed as of the acquisition date: Estimated Fair Value at January 3, 2017 Inventories (1) $ 108.6 Marketed products (2) 297.0 Property and equipment 148.2 Other assets and liabilities — net 8.2 Total identifiable net assets 562.0 Goodwill (3) 320.1 Total consideration transferred — net of cash acquired $ 882.1 (1) The fair value for inventories include a purchase accounting adjustment to write up the inventory value, which resulted in incremental cost of sales of $42.7 million in 2017. The fair value was determined by estimating the expected sales price of the inventories, reduced for all costs expected to the incurred and a profit on those costs. (2) These intangible assets, which are being amortized on a straight-line basis over their estimated useful lives, were expected to have a weighted average useful life of 10 years . (3) The goodwill recognized from this acquisition is attributable primarily to expected synergies from combining the operations of BIVIVP with our legacy business, future unidentified projects and products, and the assembled workforce of BIVIVP. The goodwill associated with this acquisition is deductible for tax purposes. Our combined statement of operations for the year ended December 31, 2017 included BIVIVP revenues of $216.7 million . We are unable to provide the results of operations attributable to BIVIVP as those operations were substantially integrated into our legacy business. Had BIVIVP been acquired on January 1, 2016, the unaudited pro forma combined revenues of Elanco and BIVIVP would have been $2.89 billion and $3.14 billion for the years ended December 31, 2017 and 2016, respectively. It is impractical to determine the pro forma impact on loss before tax attributable to BIVIVP for 2017 and 2016. Galliprant Acquisition On April 22, 2016, we acquired from Aratana, certain rights to Galliprant, a canine pain treatment for osteoarthritis for a total purchase price of $88.6 million , which consisted of an upfront payment of $45.0 million and contingent consideration of $43.6 million . The contingent consideration represented the fair value of potential future payments to Aratana based on the probability of achieving contingent milestones and royalties. At the time of the acquisition, Galliprant was approved in the U.S. and was still under development outside the U.S. Under the terms of the agreement, we were granted co-promotion rights in the U.S. through December 31, 2018, at which time we will control commercialization in the U.S. We received full commercialization rights outside the U.S. The agreement requires payments by us to Aratana associated with certain development, success-based regulatory and sales-based milestones and royalties. As of December 31, 2018 , Aratana is eligible to receive up to $8.0 million of potential development and success-based regulatory milestones. Aratana is also eligible to receive up to $60.0 million of potential sales-based milestones. Aratana is eligible to receive royalties based on a percentage of net sales of Galliprant, dependent on the timing and geography of the net sales. There is no cap on the amount of royalties that may be paid pursuant to this arrangement. As of December 31, 2018, we paid Aratana $15 million related to a sales-based milestone. The following table summarizes the amounts recognized for assets acquired and liabilities assumed as of the acquisition date: Estimated Fair Value at April 22, 2016 Deferred tax assets $ 15.3 Acquired in-process research and development 31.6 Marketed products(1) 57.0 Deferred tax liabilities (15.3 ) Total consideration 88.6 Less: Contingent consideration (43.6 ) Total cash paid $ 45.0 (1) These intangible assets, which are being amortized on a straight-line basis over their estimated useful lives, were expected to have a weighted average useful life of 20 years .

Asset Impairment, Restructuring

Asset Impairment, Restructuring and Other Special Charges	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Asset Impairment, Restructuring and Other Special Charges	Asset Impairment, Restructuring and Other Special Charges The Company's total charges related to asset impairment, restructuring and other special charges, including integration of acquired businesses, in our consolidated and combined statements of operations consisted of the following for the years ended December 31: 2018 2017 2016 Cash expense: Severance and other $ 15.5 $ 162.0 $ 42.1 Integration 26.5 90.3 154.8 Facility exit costs 5.7 31.8 13.2 Total cash expense 47.7 284.1 210.1 Non-cash expense: Asset impairment 81.9 110.6 98.3 Total non-cash expense 81.9 110.6 98.3 Gain on sale of fixed assets (0.8 ) (19.6 ) — Total expense $ 128.8 $ 375.1 $ 308.4 Restructuring We historically participated in Lilly’s cost-reduction initiatives, which resulted in restructuring charges in the period prior to our IPO. The restructuring charges include severance and other costs associated with the reduction of our workforce, including special termination benefits recognized in 2017 associated with the U.S. voluntary early retirement program offered by Lilly, related to our employees and pension curtailment costs and facility exit costs. We also recorded certain impairment charges related to the activities as described below. During December 2018, we initiated a restructuring program to streamline our international operations, including shifting focus and resources to priority areas. Among other actions, the restructuring reflects a change from having a physical location to a distribution model in certain countries in connection with our separation from Lilly and resulted in the recognition of severance costs. In addition, as part of our ongoing activities to separate fully from Lilly, we wrote off certain assets that we have determined will not be utilized in the business on an ongoing basis. We expect to substantially complete the restructuring activities by December 2019 . Integration costs Integration costs recognized during the years ended December 31, 2018, 2017 and 2016 were related to our integration efforts as a result of our acquired businesses and costs to stand our organization up to be an independent company. Asset impairment Asset impairment recognized during the year ended December 31, 2018 includes $22.5 million of intangible asset impairments and $59.4 million of other asset impairments. The intangible asset impairments primarily related to revised projections of fair value due to product rationalization. The fixed asset impairments were primarily due to the decision to dispose of a manufacturing facility in the U.S., the suspension of commercial activities for Imrestor® and the write-off of certain idle assets in a U.S. manufacturing facility. See Note 11 for further detail relating to intangible asset impairments. Asset impairment recognized during the year ended December 31, 2017 resulted primarily from intangible asset impairments related to revised projections of fair value due to product rationalization and to a lesser extent competitive pressures. Asset impairment recognized during the year ended December 31, 2016 resulted from intangible asset impairments due to product rationalization and to charges related to site closures resulting from our acquisition and integration of Novartis AH, including the closure of a manufacturing facility in Ireland in 2016. Gain on sale The gain on sale of fixed assets for the year ended December 31, 2017 represents a gain on the disposal of a site that was previously closed as part of the acquisition and integration of Novartis Animal Health beginning on January 1, 2015. The following table summarizes the activity in our reserves established in connection with these restructuring activities: Exit costs Severance Total Balance at December 31, 2016 $ 11.5 $ 26.6 $ 38.1 Charges 31.8 162.0 193.8 Reserve adjustment 1.4 (3.9 ) (2.5 ) Cash paid (9.8 ) (141.6 ) (151.4 ) Balance at December 31, 2017 34.9 43.1 78.0 Charges 11.7 15.5 27.2 Separation adjustment (5.9 ) — (5.9 ) Reserve adjustment (6.0 ) — (6.0 ) Cash paid (25.4 ) (23.5 ) (48.9 ) Balance at December 31, 2018 $ 9.3 $ 35.1 $ 44.4 Substantially all of the reserves are expected to be paid in the next twelve months. We believe that the reserves are adequate.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Inventories	Inventories We state all inventories at the lower of cost or market. We use the last-in, first-out (LIFO) method for a portion of our inventories located in the continental U.S. Other inventories are valued by the first-in, first-out (FIFO) method. FIFO cost approximates current replacement cost. Inventories at December 31 consisted of the following: 2018 2017 Finished products $ 400.7 $ 452.0 Work in process 570.4 580.0 Raw materials and supplies 80.4 70.4 Total (approximates replacement cost) 1,051.5 1,102.4 Decrease to LIFO cost (47.4 ) (40.1 ) Inventories $ 1,004.1 $ 1,062.3 Inventories valued under the LIFO method comprised $194.8 million and $231.4 million of total inventories at December 31, 2018 and 2017, respectively. During the year ended December 31, 2018, we recognized $38.6 million of inventory write-offs in cost of sales primarily related to the suspension of commercial activities for Imrestor.

Debt

Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt	Debt Long-term debt as of December 31, 2018 consisted of the following: December 31, 2018 Term credit facility $ 492.5 3.912% Senior Notes due 2021 500.0 4.272% Senior Notes due 2023 750.0 4.900% Senior Notes due 2028 750.0 Other obligations 0.5 Unamortized debt issuance costs (20.7 ) 2,472.3 Less current portion of long-term debt (29.0 ) Total long-term debt $ 2,443.3 Long-term debt as of December 31, 2017 was not material. Revolving and Term Credit Facilities On September 5, 2018, we entered into a revolving credit agreement with a syndicate of banks providing for a five -year $750.0 million senior unsecured revolving credit facility (Revolving Facility). The Revolving Facility bears interest at a variable rate plus specified margin as defined in the agreement and is payable quarterly. There were no borrowings outstanding under the Revolving Facility at December 31, 2018. The Revolving Facility is payable in full at the end of the term. On September 5, 2018 we also entered into a $500.0 million three -year term loan under a term credit facility with a syndicate of banks (the Term Facility and collectively with the Revolving Facility, the Credit Facilities.) The Term Facility bears interest at a variable rate plus margin as defined in Term Facility ( 3.77% at December 31, 2018) and is payable quarterly. The Term Facility also requires a quarterly principal payment equal to 1.5% of the aggregate initial principal less any prepayment. The Term Facility is payable in full at the end of the term. The Credit Facilities are subject to various financial and other covenants including restrictions on the level of borrowings based on a consolidated leverage ratio and a consolidated interest coverage ratio. We were in compliance with all such covenants as of December 31, 2018. Senior Notes On August 28, 2018 , we issued $2.0 billion of senior notes (Senior Notes) in a private placement. The Senior Notes comprised of $500.0 million of 3.912% Senior Notes due August 27, 2021 , $750.0 million of 4.272% Senior Notes due August 28, 2023 , and $750.0 million of 4.900% Senior Notes due August 28, 2028 . The interest rate payable on each series of Senior Notes is subject to adjustment if Moody's Investor Services, Inc. or Standard & Poor's Financial Services LLC downgrades, or subsequently upgrades, its ratings on the respective series of Senior Notes. The indenture that governs the Senior Notes contains covenants, including limitations on our ability, and certain of our subsidiaries, to incur liens or engage in sale-leaseback transactions. The indenture also contains restrictions on our ability to consolidate, merge or sell substantially all of our assets, in addition to other customary terms. We were in compliance with all such covenants under the indenture governing the Senior Notes as of December 31, 2018. We have entered into an agreement that requires us to use commercially reasonable efforts to cause a registration statement to become effective with the SEC by August 28, 2019, relating to an offer to exchange the Senior Notes for registered Senior Notes having substantially identical terms, or, in certain cases, to register the Senior Notes for resale. If we do not register or exchange the Senior Notes pursuant to the terms of the registration rights agreement, we will be required to pay additional interest to the holders of the Senior Notes under certain circumstances.

Financial Instruments and Fair

Financial Instruments and Fair Value	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Financial Instruments and Fair Value	Financial Instruments and Fair Value Financial instruments that are potentially subject to credit risk consist principally of trade receivables. Collateral is generally not required. The risk associated with this concentration is mitigated by our ongoing credit-review procedures and insurance. A large portion of our cash is held by a few major financial institutions. We monitor the exposure with these institutions and do not expect any of these institutions to fail to meet their obligations. All highly liquid investments with a maturity of three months or less from the date of purchase are considered to be cash equivalents. The cost of these investments approximates fair value. We also consider the carrying value of restricted cash balances to be representative of its fair value. As of December 31, 2018 and 2017, we had $15.3 million and $12.3 million , respectively, primarily related to equity method investments. The following table summarizes the fair value information at December 31, 2018 and 2017 for contingent consideration liabilities and net investment hedge liability measured at fair value on a recurring basis in the respective balance sheet line items: Fair Value Measurements Using Financial statement line item Carrying Amount Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value December 31, 2018 Other current liabilities- contingent consideration $ 5.1 $ — $ — $ 5.1 $ 5.1 Other noncurrent liabilities- contingent consideration 69.0 — — 69.0 69.0 Other noncurrent liabilities- cross currency interest rate contracts designated as net investment hedges 7.4 — 7.4 — 7.4 December 31, 2017 Other current liabilities- contingent consideration 1.3 — — 1.3 1.3 Other noncurrent liabilities- contingent consideration 45.2 — — 45.2 45.2 We determine our Level 1 and Level 2 fair value measurements based on a market approach using quoted market values, significant other observable inputs for identical or comparable assets or liabilities, or discounted cash flow analysis. Level 3 fair value measurements for other investment securities are determined using unobservable inputs, including the investments' cost adjusted for impairments and price changes from orderly transactions. The fair values of cost and equity method investments are not readily available. Contingent consideration liabilities relate to Galliprant for which the fair value was estimated using a discounted cash flow analysis and Level 3 inputs, including projections representative of a market participant view for the probability of achieving potential future payments to Aratana Therapeutics, Inc. and an estimated discount rate. The amount to be paid is dependent upon certain development, success-based regulatory, and sales-based milestones. In addition, the amount of royalties to be paid is calculated as a percentage of net sales dependent upon the timing and geography and will, therefore, vary directly with increases and decreases in net sales of Galliprant . There is no cap on the amount that may be paid pursuant to this arrangement. During 2018, as a result of an increase in the projected cash flows related to Galliprant, we increased the fair value of the contingent consideration liabilities by $37.6 million , offset by a $15.0 million sales-based milestone payment. The additional expense was recognized in other (income) expense, net. We have long term debt of $2.5 billion that is recorded at amortized cost in our consolidated and combined balance sheet as of December 31, 2018. We consider the carrying value of the long term debt to be representative of its fair value as of December 31, 2018. The fair value of this long term debt is estimated based on quoted market prices of similar liabilities and is classified as Level 2. As of December 31, 2017, long term debt was not material. In October 2018, we entered into a cross-currency fixed interest rate swap, 5 -year, 750 million Swiss Franc (CHF), which is designated as a NIH against CHF denominated assets for which the fair value was estimated based on quoted market values of similar hedges and is classified as Level 2. The NIH is expected to generate approximately $25 million in cash and an offset to interest expense on an annual basis. During the year ended December 31, 2018, our interest expense was offset by $5.6 million as a result of the NIH. Over the life of the derivative, gains or losses due to spot rate fluctuations are recorded in cumulative translation adjustment. During the year ended December 31, 2018, we recorded a $5.9 million loss, net of tax, on the NIH, which is included in the change in the cumulative translation adjustment in other comprehensive income. There is a potential for significant 2023 settlement exposure as the U.S. dollar fluctuates against the Swiss Franc. The risk management objective is to manage foreign currency risk relating to net investments in certain CHF denominated assets. Changes in fair value of the derivative instruments are recognized in a component of Accumulated Other Comprehensive Loss to offset the changes in the values of the net investments being hedged.

Goodwill and Intangibles

Goodwill and Intangibles	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangibles	Goodwill and Intangibles Goodwill Goodwill was $3.0 billion as of December 31, 2018 and 2017. Goodwill results from excess consideration in a business combination over the fair value of identifiable net assets acquired. Goodwill is not amortized but is reviewed for impairment at least annually and when impairment indicators are present. Goodwill may be impaired if the carrying amount of a reporting unit exceeds the fair value of that reporting unit, calculated as based on discounted cash flows. The implied fair value of goodwill is then determined by subtracting the fair value of all identifiable net assets other than goodwill from the fair value of the reporting unit. An impairment charge would be recorded for the excess, if any, of carrying amount of goodwill over the implied fair value. The estimated fair value is based on a number of assumptions, including current market capitalization as corroboration of fair value. See Note 6 for further discussion of goodwill resulting from recent business combinations. The remaining change in goodwill is primarily the result of foreign exchange translation adjustments. No impairments occurred with respect to the carrying value of goodwill for the years ended December 31, 2018, 2017 and 2016. Other Intangibles The components of intangible assets other than goodwill at December 31 were as follows: 2018 2017 Description Carrying Amount, Gross Accumulated Amortization Carrying Amount, Net Carrying Amount, Gross Accumulated Amortization Carrying Amount, Net Finite-lived intangible assets: Marketed products $ 3,193.5 $ (779.2 ) $ 2,414.3 $ 3,151.2 $ (599.8 ) $ 2,551.4 Other 53.1 (34.0 ) 19.1 54.1 (29.9 ) 24.2 Total finite-lived intangible assets 3,246.6 (813.2 ) 2,433.4 3,205.3 (629.7 ) 2,575.6 Indefinite-lived intangible assets: Acquired in-process research and development 19.6 — 19.6 97.2 — 97.2 Other intangibles $ 3,266.2 $ (813.2 ) $ 2,453.0 $ 3,302.5 $ (629.7 ) $ 2,672.8 Marketed products consist of the amortized cost of the rights to assets acquired in business combinations and approved for marketing in a significant global jurisdiction. For transactions other than a business combination, we capitalize milestone payments incurred at or after the product has obtained regulatory approval for marketing. Other finite-lived intangibles consist primarily of the amortized cost of licensed platform technologies that have alternative future uses in research and development, manufacturing technologies and customer relationships from business combinations. Acquired IPR&D consists of the related costs capitalized, adjusted for subsequent impairments, if any. The costs of acquired IPR&D projects acquired directly in a transaction other than a business combination are capitalized if the projects have an alternative future use; otherwise, they are expensed immediately. The fair values of acquired IPR&D projects acquired in business combinations are capitalized as other intangible assets. Several methods may be used to determine the estimated fair value of other intangibles acquired in a business combination. We utilize the "income method" for other intangibles. This method is a Level 3 fair value measurement and applies a probability weighting that considers the risk of development and commercialization to the estimated future net cash flows that are derived from projected revenues and estimated costs. These projections are based on factors such as relevant market size, patent protection, historical pricing of similar products and expected industry trends. The estimated future net cash flows are then discounted to the present value using an appropriate discount rate. This analysis is performed for each group of assets independently. The acquired IPR&D assets are treated as indefinite-lived intangible assets until completion or abandonment of the projects, at which time the assets are tested for impairment and amortized over the remaining useful life or written off, as appropriate. See Note 6 for further discussion of intangible assets acquired in recent business combinations. Other indefinite-lived intangible assets are reviewed for impairment at least annually and when impairment indicators are present. The fair value of the indefinite lived intangible assets (acquired IPR&D) is estimated using the same assumptions as used for goodwill and by applying a probability weighting that reflects the risk of development and commercialization to the estimated future net cash flows that are derived from projected revenues and estimated costs. Finite-lived intangible assets are reviewed for impairment when an indicator of impairment is present. We compare the carrying amounts of the assets with the estimated undiscounted future cash flows. In the event the carrying amount exceeds the undiscounted cash flows, an impairment charge is recorded for the amount by which the carrying amount of the asset exceeds the estimated fair value, which is determined based on discounted future cash flows. During 2018, we recorded impairment charges of $22.5 million (comprised of $9.5 million impairment of finite-lived intangible assets and $13.0 million impairment of indefinite-lived intangible assets) which are included in asset impairment, restructuring and other special charges on the combined statements of operations. The impairment of finite-lived intangible assets primarily related to competitive pressures for a certain marketed product resulting in a reduction of projected cash flows. The impairment of indefinite-lived intangible assets primarily related to revised projections of fair value due to competitive pressures and to a lesser extent product rationalization. The increase in the carrying amount of finite intangibles is primarily due to the receipt of full commercialization rights outside the U.S. for Galliprant. During 2017, we had impairment charges of $94.5 million (comprised of $56.5 million impairment of finite-lived intangible assets and $38.0 million impairment of indefinite-lived intangible assets) which are included in asset impairment, restructuring and other special charges on the combined statements of operations. The impairment of finite-lived intangible assets primarily related to competitive pressures for a certain marketed product resulting in a reduction of projected cash flows. The impairment of indefinite-lived intangible assets primarily related to revised projections of fair value due to competitive pressures and to a lesser extent product rationalization. During 2016, we recorded impairment charges of $14.0 million primarily related to indefinite-lived intangible assets charged to asset impairment, restructuring and other special charges on the combined statements of operations. The impairments in 2016 were related to product rationalization. Intangible assets with finite lives are capitalized and are amortized over their estimated useful lives, ranging from 3 to 20 years . As of December 31, 2018, the remaining weighted-average amortization period for finite-lived intangible assets is approximately 14 years . The estimated amortization expense for each of the next five years associated with our finite-lived intangible assets as of December 31, 2018 is as follows: 2019 2020 2021 2022 2023 Estimated amortization expense $ 197.9 $ 198.3 $ 198.0 $ 196.0 $ 195.8

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment is stated on the basis of cost. Provisions for depreciation of buildings and equipment are computed generally by the straight-line method at rates based on their estimated useful lives ( 12 to 50 years for buildings and 3 to 25 years for equipment). We review the carrying value of long-lived assets for potential impairment on a periodic basis and whenever events or changes in circumstances indicate the carrying value of an asset may not be recoverable. Impairment is determined by comparing projected undiscounted cash flows to be generated by the asset to its carrying value. If an impairment is identified, a loss is recorded equal to the excess of the asset's net book value over its fair value utilizing a discounted cash flow analysis, and the cost basis is adjusted. At December 31, property and equipment consisted of the following: 2018 2017 Land $ 27.6 $ 25.1 Buildings 567.2 557.7 Equipment 1,025.1 994.5 Construction in progress 181.1 177.1 1,801 1,754.4 Less accumulated depreciation (878.6 ) (834.1 ) Property and equipment, net $ 922.4 $ 920.3 Depreciation expense related to property and equipment and rental expense for all leases was as follows: 2018 2017 2016 Depreciation expense $ 81.3 $ 79.8 $ 75.7 Rental expense 47.5 47.1 41.8 The future minimum rental commitments under non-cancelable operating leases are as follows: 2019 2020 2021 2022 2023 After 2023 Lease commitments $ 25.2 $ 20.1 $ 13.5 $ 10.0 $ 8.3 $ 18.5

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation	Stock-Based Compensation Lilly Stock Compensation Plans For periods prior to IPO, we benefited from Lilly's stock-based compensation program. Lilly maintains various stock-based compensation programs for the benefit of its officers, directors and certain employees including employees of the Company. As we receive the employee services in consideration for the participation of the Company's employees in these plans, stock-based compensation expense for the awards granted to our employees has been reflected in the consolidated and combined statements of operations. Lilly's stock-based compensation granted to our employees consists of performance awards (PAs), shareholder value awards (SVAs) and RSUs. The stock-based compensation expense has been derived from the equity awards granted by Lilly to our employees. The compensation expense is based on the fair value of stock-based awards which is recognized as compensation expense over the requisite service period of the individual grantees, which generally equals the vesting period. The awards are settled by Lilly. For the periods prior to IPO, as the stock-based compensation plans were Lilly's plans and the awards were settled by Lilly, the offset to the expense was recognized through net parent company investment on the combined balance sheet. Stock-based compensation expense related to our employees for years ended December 31, 2018, 2017 and 2016 was $26.0 million , $25.0 million and $20.4 million , respectively. Following IPO and until the completion of the exchange offer, the equity awards previously granted to our employees by Lilly will continue to vest, and service with Elanco counts toward the Lilly award’s vesting provisions. Upon completion of the exchange offer, we expect that our employees’ unvested Lilly RSUs, PAs, and SVAs will be forfeited and replaced with Elanco RSUs valued at the exchange rate with the same service vesting period as the forfeited Lilly awards. Performance Award Program PAs have been granted to certain of our officers and management and are settled in shares of Lilly's common stock. The number of PA shares actually issued, if any, varies depending on the achievement of certain pre-established earnings-per-share targets over a two -year period. PA shares are accounted for at fair value based upon the closing stock price on the date of grant and fully vest at the end of the measurement period. The fair values of PAs granted for the years ended December 31, 2018, 2017 and 2016 were $71.63 , $73.54 , and $72.00 , respectively. The number of PA shares that will vest for the PA program is dependent upon Lilly's earnings achieved during the vesting period. Pursuant to this program, approximately 39,771 shares, 69,144 shares and 20,329 shares were issued by Lilly to our employees during the years ended December 31, 2018, 2017 and 2016, respectively. As of December 31, 2018, the total remaining unrecognized compensation cost related to nonvested PAs was $5.8 million , which will be amortized over the weighted-average remaining requisite service period of 12 months . Shareholder Value Award Program SVAs have been granted to certain of our officers and management and are settled in shares of Lilly's common stock. The number of shares actually issued, if any, varies depending on Lilly's stock price at the end of the three -year vesting period compared to pre-established target stock prices. We measure the fair value of the SVA unit on the grant date using a Monte Carlo simulation model. The model utilizes multiple input variables that determine the probability of satisfying the market condition stipulated in the award grant and calculates the fair value of the award. Expected volatilities utilized in the model are based on implied volatilities from traded options on Lilly's stock, historical volatility of Lilly's stock price and other factors. Similarly, the dividend yield is based on historical experience and Lilly's estimate of future dividend yields. The risk-free interest rate is derived from the U.S. Treasury yield curve in effect at the time of grant. The weighted-average fair values of the SVA units granted during the years ended December 31, 2018, 2017 and 2016 were $49.38 , $66.25 and $48.68 , respectively, determined using the following assumptions: (Percents) 2018 2017 2016 Expected dividend yield 2.50 % 2.50 % 2.00 % Risk-free interest rate 2.31 1.38 0.92 Volatility 22.26 22.91 21.68 Pursuant to this program, Lilly issued approximately 30,195 shares, 35,063 shares and 36,071 shares to our employees during the years ended December 31, 2018, 2017 and 2016, respectively. As of December 31, 2018, the total remaining unrecognized compensation cost related to nonvested SVAs was $3.5 million , which will be amortized over the weighted-average remaining requisite service period of 20 months . Restricted Stock Units RSUs have been granted to certain of our employees and are payable in shares of Lilly's common stock. RSU shares are accounted for at fair value based upon Lilly's closing stock price on the date of grant. The corresponding expense is amortized over the vesting period, typically three years . The fair values of RSU awards granted during the years ended December 31, 2018, 2017 and 2016 were $70.95 , $72.47 and $71.46 , respectively. The number of shares ultimately issued by Lilly for the RSU program remains constant with the exception of forfeitures. Pursuant to this program, 82,025 shares, 57,224 shares and 26,468 shares were settled by Lilly with its RSUs to our employees during the years ended December 31, 2018, 2017 and 2016, respectively. As of December 31, 2018, the total remaining unrecognized compensation cost related to nonvested RSUs was $12.5 million which will be amortized over the weighted-average remaining requisite service period of 20 months . Elanco Stock Compensation Plans In connection with IPO, we adopted our own stock based compensation plans, including RSUs and stock options. Our stock-based compensation expense and the related tax under these plans for the year ended December 31, 2018 was $1.8 million and $0.4 million . Restricted Stock Units RSUs are granted to certain employees and are settled in shares of our common stock. RSU shares are accounted for at fair value based upon the closing stock price on the date of the grant. The corresponding expense is amortized over the vesting period, typically three years . The fair value of the RSU awards granted during the year ended December 31, 2018 was $31.09 . The number of shares ultimately issued for the RSU program remains constant with the exception of forfeitures. Pursuant to this program, 158,007 shares were granted and 18,991 shares were issued during the year ended December 31, 2018. As of December 31, 2018, the total remaining unrecognized compensation cost related to nonvested RSUs was $3.9 million , which will amortize over the weighted-average remaining requisite service period of 33 months . Stock Option Program Stock options represent the right to purchase shares of our common stock within a specified period of time at a specified price. The exercise price for a stock option will be not less than 100% of the fair market value of the common stock on the date of the grant. Stock options are accounted for using a fair-value based method at the date of the grant in the consolidated statement of operations. The values determined through this fair-value-based method generally are amortized on a straight-line basis over the vesting term. Stock options were granted in 2018 to our officers, management and board members at exercise prices equal to the fair market value of our stock at the date of the grant. Options fully vest 3 years from the grant date and have a term of 10 years . The fair-value-based method for valuing each Elanco stock option grant on the grant date uses the Black-Scholes-Merton option-pricing model, which incorporates a number of valuation assumptions noted in the following table, shown at their weighted-average values for the year ended December 31: 2018 Expected dividend yield (1) 0.70 % Risk-free interest rate (2) 3.07 % Expected stock price volatility (3) 28.25 % Expected term (4) (years) 6.5 (1) Determined using the expected quarterly dividend divided by the available three-month average stock price as of the valuation date, annualized and continuously compounded. (2) Determined using the term-matched, zero-coupon risk-free rate from the Treasury Constant Maturity yield curve, continuously compounded (3) Determined using a leverage-adjusted historical volatility of peer companies (4) Determined using SEC safe harbor approach, based on a 3 -year cliff vesting schedule and 10 -year contractual term. Stock option activity during the year ended December 31, 2018 is summarized below: Shares of Common Stock Attributable to Options Weighted-Average Exercise Price of Options Outstanding at January 1, 2018 — $ — Granted 421,297 31.61 Exercised — — Forfeited or expired — — Outstanding at December 31, 2018 421,297 31.61 Exercisable at December 31, 2018 58,766 31.61 As of December 31, 2018, the weighted-average remaining contractual term of the exercisable options was 9.8 years and the aggregate intrinsic value was $0.08 .

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes During the periods presented in the consolidated and combined financial statements, Elanco was generally included in the tax grouping of other Lilly entities within the respective entity's tax jurisdiction; however, in certain jurisdictions, Elanco filed separate tax returns. The income tax (benefit)/expense included in these consolidated and combined financial statements has been calculated using the separate return basis, as if Elanco filed separate tax returns. 2017 Tax Act In December 2017, the President of the U.S. signed into law the Tax Cuts and Jobs Act (2017 Tax Act). The 2017 Tax Act includes significant changes to the U.S. corporate income tax system, such as the reduction in the corporate income tax rate from 35 percent to 21 percent, transition to a territorial tax system, changes to business related exclusions, deductions and credits, and modifications to international tax provisions, including a one-time repatriation transition tax (also known as the ‘Toll Tax’) on unremitted foreign earnings. GAAP requires that the income tax accounting effects from a change in tax laws or tax rates be recognized in continuing operations in the reporting period that includes the enactment date of the change. These effects include, among other things, re-measuring deferred tax assets and liabilities, evaluating deferred tax assets for valuation allowances and assessing the impact of the Toll Tax and certain other provisions of the 2017 Tax Act. Our accounting for the tax effects of the enactment of the 2017 Tax Act was not complete as of December 31, 2017; however, in certain cases, we made a reasonable estimate. In other cases, we were unable to make a reasonable estimate and continued to account for those items based on our existing accounting model under ASC 740, Income Taxes and the provisions of the tax laws that were in effect immediately prior to enactment. For the items for which we were able to make a reasonable estimate, we recorded a provisional tax benefit of $33.1 million in 2017 related to the impacts of the 2017 Tax Act. We finalized our accounting for the tax effects of the 2017 Tax Act during 2018. No material adjustments to income tax expense (benefit) were recorded. We expect that further guidance will continue to be issued in 2019 which may impact our interpretations of the 2017 Tax Act and could materially affect the estimates used. The 2017 Tax Act also includes a new U.S. minimum tax, global intangible low-taxed income (GILTI), on the earnings of our foreign subsidiaries. We have elected to account for the tax related to GILTI as a period cost in the year the tax is incurred. Deferred taxes are recognized for the future tax effects of temporary differences between financial and income tax reporting based on enacted tax laws and rates. We recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The tax benefits recognized in the financial statements from such a position are measured based on the largest benefit that has a greater than 50 percent likelihood of being realized upon ultimate resolution. Following is the composition of income (loss) before income tax expense (benefit): 2018 2017 2016 Federal $ 12.2 $ (133.2 ) $ (12.5 ) Foreign 101.9 (99.4 ) (9.9 ) Income (loss) before income taxes $ 114.1 $ (232.6 ) $ (22.4 ) Following is the composition of income tax expense (benefit): 2018 2017 2016 Current: Federal $ 45.1 $ — $ — Foreign 45.5 91.6 31.1 State (2.3 ) (0.1 ) 0.3 Total current tax expense 88.3 91.5 31.4 Deferred: Federal (56.8 ) 42.6 18.4 Foreign (5.6 ) (16.6 ) (26.8 ) State 1.7 (6.3 ) 2.5 2017 Tax Act — (33.1 ) — Total deferred tax benefit (60.7 ) (13.4 ) (5.9 ) Income taxes $ 27.6 $ 78.1 $ 25.5 Significant components of our deferred tax assets and liabilities as of December 31 are as follows: 2018 2017 Deferred tax assets: Compensation and benefits $ 32.2 $ 34.8 Accruals and reserves 47.8 12.0 Tax credit carryovers 1.9 19.2 Tax loss carryovers 21.7 144.9 Other 23.5 26.6 Total gross deferred tax assets 127.1 237.5 Valuation allowances (21.4 ) (127.7 ) Total deferred tax assets 105.7 109.8 Deferred tax liabilities: Intangibles (130.8 ) (165.2 ) Property and equipment (50.8 ) (43.1 ) Other (2.7 ) (7.4 ) Total deferred tax liabilities (184.3 ) (215.7 ) Deferred tax liabilities - net $ (78.6 ) $ (105.9 ) Deferred tax assets and liabilities reflect the impact of re-measurement resulting from the 2017 Tax Act. The deferred tax assets and related valuation allowance amounts for U.S. federal and state net operating losses and tax credits shown above have been reduced for differences between financial reporting and tax return filings. At December 31, 2018, we have tax credit carryovers of $6.5 million available to reduce future income taxes. The amount is comprised of foreign and state credits. Foreign credits total $4.1 million and if unused, will expire beginning in 2032. State tax credits of $2.4 million are fully reserved. At December 31, 2018, we had net operating loss carryovers and other carryovers for international and U.S. state income tax purposes of $156.2 million : $84.6 million will expire by 2023; $65.0 million will expire by 2025; and $1.6 million of the carryovers will never expire. Net operating losses and other carryovers for international and U.S. state income tax purposes are partially reserved. Deferred tax assets related to state net operating losses of $4.9 million are fully reserved. The movements in the valuation allowance are as follows: 2018 2017 January 1 $ (127.7 ) $ (39.1 ) Adjustment related to Separation 110.4 — January 1 (17.3 ) (39.1 ) Increase (5.8 ) (97.4 ) Release 1.7 8.8 December 31 $ (21.4 ) $ (127.7 ) Prior to the IPO, we prepared the income tax amounts and balances based upon a separate return methodology, as if we were separate taxpayers from Lilly. As a result, certain tax credit and net operating loss carryovers are not available for use in future periods as they were used in Lilly consolidated or combined tax return filings. Accordingly, as a result of the Separation, the tax credit and net operating loss carryovers and related valuation allowance have been adjusted to reflect the balance after Separation. These adjustments had no impact on income tax expense in the consolidated and combined financial statements. The separation entries related to the valuation allowance were offset by $133.7 million , prior to tax effect, of separation entries related to the removal of the net operating losses. The 2017 Tax Act introduced international tax provisions that significantly change the U.S. taxation of foreign earnings. At December 31, 2018, no U.S. taxes or foreign withholding taxes have been accrued with respect to the $464.5 million in unremitted earnings of our foreign subsidiaries as they are considered indefinitely reinvested for continued use in our foreign operations. It is not practicable to determine the unrecognized deferred tax liability related to these earnings. Cash payments of income taxes were as follows: 2018 2017 2016 Cash payments of income taxes $ 26.9 $ 35.7 $ 53.6 The following is a reconciliation of the income tax expense (benefit) applying the U.S. federal statutory rate to income before income taxes to reported income tax expense: 2018 2017 2016 Income tax at the U.S. federal statutory tax rate $ 24.0 $ (81.4 ) $ (7.8 ) Add (deduct): International operations and change in foreign tax rates 11.5 55.6 8.4 State taxes 4.4 5.4 2.8 Income tax credits (17.3 ) (1.8 ) (1.7 ) Foreign inclusion items 9.0 4.2 2.4 IPO and separation costs 2.3 — — Other permanent adjustments 0.9 1.6 0.2 Change in uncertain tax positions (1.7 ) 6.2 5.2 Change in valuation allowance (1.7 ) 122.2 18.1 2017 Tax Act — (33.1 ) — Other (3.8 ) (0.8 ) (2.1 ) Income taxes $ 27.6 $ 78.1 $ 25.5 A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows: 2018 2017 2016 Beginning balance at January 1 $ 29.6 $ 25.7 $ 25.5 Adjustments related to Separation (17.6 ) — — Beginning balance at January 1 12.0 25.7 25.5 Additions based on tax positions related to the current year 2.2 7.9 7.4 Additions for tax positions of prior years 4.0 — — Settlements (3.0 ) (4.0 ) (7.1 ) Changes related to the impact of foreign currency translation (0.5 ) — (0.1 ) Ending balance at December 31 $ 14.7 $ 29.6 $ 25.7 The total amount of unrecognized tax benefits that, if recognized, would affect tax expense by $12.8 million and $29.6 million at December 31, 2018 and 2017, respectively. There are $1.9 million of 2018 unrecognized tax benefits which related to temporary differences which would not, if recognized, impact the effective tax rate. Adjustments related to the Separation represent unrecognized tax benefits assumed by Lilly in the Separation and have no impact on income tax expense in the consolidated and combined financial statements. We file income tax returns in the U.S. federal jurisdiction and various state, local and non-U.S. jurisdictions. Certain of these income tax returns are filed on a consolidated or combined basis with Eli Lilly and Company and/or its subsidiaries. We are included in Lilly's U.S. tax examinations by the Internal Revenue Service. Pursuant to the Tax Matters Agreement we executed with Lilly in connection with the IPO, the liabilities or potential refunds attributable to pre-IPO periods in which Elanco was included in a Lilly consolidated or combined tax return remain with Lilly. Consequently, although a U.S. examination of tax years 2013-2015 is currently in progress, the resulting adjustments, if any, will not require any cash tax payments by Elanco. We are not otherwise subject to U.S. federal, state and local, or non-U.S. income tax examinations in most major taxing jurisdictions for years before 2013. We recognize both accrued interest and penalties related to unrecognized tax benefits in income tax expense (benefit). We recognized income tax expense (benefit) related to interest and penalties as follows: 2018 2017 2016 Income tax expense (benefit) $ (2.5 ) $ 2.5 $ 5.5 At December 31, 2018 and 2017, our accruals for the payment of interest and penalties totaled $13.3 million and $15.7 million , respectively.

Contingencies

Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies We are party to various legal actions in the normal course of business. In determining whether a pending matter is significant for financial reporting and disclosure purposes, we consider both quantitative and qualitative factors in order to assess materiality. We accrue for certain liability claims to the extent we can formulate a reasonable estimate of their costs and there is a reasonable probability of incurring significant costs or expenses. At December 31, 2018 and December 31, 2017, we had no liabilities established related to litigation as there were no significant claims which were probable and estimable. We have not historically had any significant litigation expense and are not currently subject to a significant claim.

Geographic Information

Geographic Information	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Geographic Information	Geographic Information We operate as a single operating segment engaged in the development, manufacturing, marketing and sales of animal health products worldwide for both food animals and companion animals. Consistent with our operational structure, our President and Chief Executive Officer (CEO), as the chief operating decision maker, makes resource allocation and business process decisions globally across our consolidated business. Strategic decisions are managed globally with global functional leaders responsible for determining significant costs/investments and with regional leaders responsible for overseeing the execution of the global strategy. Our global research and development organization is responsible for development of new products. Our manufacturing organization is responsible for the manufacturing and supply of products and for the optimization of our supply chain. Regional leaders are responsible for the distribution and sale of our products and for local direct costs. The business is also supported by global corporate staff functions. Managing and allocating resources at the global corporate level enables our CEO to assess the overall level of resources available and how to best deploy these resources across functions, product types, regional commercial organizations and research and development projects in line with our overarching long-term corporate-wide strategic goals, rather than on a product or geographic basis. Consistent with this decision-making process, our CEO uses consolidated, single-segment financial information for purposes of evaluating performance, allocating resources, setting incentive compensation targets, as well as forecasting future period financial results. Our products include Rumensin®, Optaflexx®, Denagard®, Tylan®, Maxiban® and other products for livestock and poultry, as well as Trifexis®, Interceptor®, Comfortis® and other products for companion animals. Our results for the year ended December 31, 2017 includes the results of operations from BIVIVP, which was acquired on January 3, 2017 (Note 6). We have a single customer that accounted for 11.9% , 12.9% and 11.7% of revenue for the years ended December 31, 2018, 2017 and 2016, respectively, and that represented accounts receivable of $96.4 million and $88.0 million as of December 31, 2018 and 2017, respectively. We are exposed to the risk of changes in social, political and economic conditions inherent in foreign operations and our results of operations and the value of our foreign assets are affected by fluctuations in foreign currency exchange rates. Selected geographic area information was as follows: 2018 2017 2016 Geographic Information Revenue — to unaffiliated customers (1) : United States $ 1,483.2 $ 1,373.0 $ 1,361.6 International 1,583.6 1,516.0 1,551.9 Revenue $ 3,066.8 $ 2,889.0 $ 2,913.5 Long-lived assets (2) : United States $ 602.6 $ 604.7 $ 463.8 United Kingdom 187.5 204.4 190.6 Other foreign countries 195.8 190.2 173.0 Long-lived assets $ 985.9 $ 999.3 $ 827.4 (1) Revenue is attributed to the countries based on the location of the customer. (2) Long-lived assets consist of property and equipment, net, and certain noncurrent assets.

Retirement Benefits

Retirement Benefits	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Retirement Benefits	Retirement Benefits Shared Lilly Plans Our employees participated in defined benefit pension and other postretirement plans sponsored by Lilly, which include participants of Lilly's other business. Such plans are accounted for as multiemployer plans in these combined financial statements and as a result, no asset or liability was recorded by the Company to recognize the funded status of these plans. We recorded expense of $4.0 million , $73.7 million and $11.3 million for the years ended December 31, 2018, 2017 and 2016, respectively, relating to our employees’ participation in Lilly sponsored plans. The expense included $67.0 million related to a curtailment loss and special termination benefits for early retirement incentives offered by Lilly to our employees as part of a voluntary early retirement program for the U.S. plan and which has been recorded in asset impairment, restructuring and other special charges. No contributions have been recognized in the combined financial statements as we are not required to make contributions to these plans. Pension Plans There are also certain defined benefit pension plans that our employees participate in that are either dedicated to our employees or where the plan assets and liabilities that relate to our employees were legally required to transfer to Elanco at the time of our separation from Lilly. The plans in Switzerland represent approximately 84 percent of our global benefit obligation. We use a measurement date of December 31 to develop the change in benefit obligation, change in plan assets, funded status and amounts recognized in the combined balance sheets at December 31 for our defined benefit pension plans, which were as follows: 2018 2017 Change in benefit obligation: Benefit obligation at beginning of year $ 258.6 $ 225.0 Service cost 11.3 10.5 Interest cost 2.5 1.8 Actuarial (gain) loss (44.7 ) 24.4 Benefits paid (2.7 ) (18.5 ) Foreign currency exchange rate changes and other adjustments 9.8 15.4 Benefit obligation at end of year 234.8 258.6 Change in plan assets: Fair value of plan assets at beginning of year 131.5 123.7 Actual return on plan assets (10.2 ) 13.3 Employer contribution 5.7 3.9 Benefits paid (2.7 ) (18.5 ) Foreign currency exchange rate changes and other adjustments 7.3 9.1 Fair value of plan assets at end of year 131.6 131.5 Funded status (103.2 ) (127.1 ) Unrecognized net actuarial loss 0.5 29.1 Unrecognized prior service cost 0.8 0.7 Net amount recognized $ (101.9 ) $ (97.3 ) Amounts recognized in the combined balance sheet consisted of: Noncurrent assets $ 2.3 $ 2.4 Other current liabilities (0.3 ) (0.3 ) Accrued retirement benefits (105.2 ) (129.2 ) Accumulated other comprehensive loss before income taxes 1.3 29.8 Net amount recognized $ (101.9 ) $ (97.3 ) The unrecognized net actuarial loss and unrecognized prior service cost for these pension plans have not yet been recognized in net periodic pension costs and are included in accumulated other comprehensive loss at December 31, 2018. During 2019, we expect the following components of accumulated other comprehensive loss to be recognized as components of net periodic benefit cost: Unrecognized net actuarial loss $ 0.5 Unrecognized prior service cost 0.8 Total $ 1.3 We do not expect any plan assets to be returned to us in 2019. The following represents our weighted-average assumptions related to these pension plans as of December 31: (Percents) 2018 2017 2016 Discount rate for benefit obligation 1.5% 1.1% 1.0% Discount rate for net benefit costs 1.1 1.0 1.0 Rate of compensation increase for benefit obligation 2.2 2.1 3.1 Rate of compensation increase for net benefit costs 2.1 3.1 3.0 Expected return on plan assets for net benefit costs 4.0 4.4 4.9 We annually evaluate the expected return on the plan assets in these pension plans. In evaluating the expected rate of return, we consider many factors, with a primary analysis of current and projected market conditions; asset returns and asset allocations; and the views of leading financial advisers and economists. We may also review our historical assumptions compared with actual results, as well as the assumptions and trend rates utilized by similar plans, where applicable. The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid as follows: 2019 2020 2021 2022 2023 2024-2028 Benefit payments $ 5.8 $ 6.4 $ 7.1 $ 6.1 $ 6.3 $ 35.9 Amounts relating to these pension plans with projected benefit obligations in excess of plan assets were as follows at December 31: 2018 2017 Projected benefit obligation $ 229.2 $ 251.6 Fair value of plan assets 124.1 121.8 Amounts relating to these defined benefit pension plans with accumulated benefit obligations in excess of plan assets were as follows at December 31: 2018 2017 Accumulated benefit obligation $ 194.3 $ 223.1 Fair value of plan assets 124.1 121.8 The total accumulated benefit obligation for these defined benefit pension plans was $199.9 million and $230.3 million at December 31, 2018 and 2017, respectively. Net pension expense related to these plans included the following components: 2018 2017 2016 Service cost $ 11.3 $ 10.5 $ 9.3 Interest cost 2.5 1.8 1.8 Expected return on plan assets (6.2 ) (2.4 ) (3.4 ) Amortization of prior service cost 0.2 0.1 0.1 Amortization of net actuarial loss 1.9 1.4 1.0 Other 0.5 — — Net pension expense $ 10.2 $ 11.4 $ 8.8 The following represents the amounts recognized for these plans in other comprehensive loss: 2018 2017 2016 Actuarial gain (loss) arising during period $ 28.3 $ (17.0 ) $ (6.1 ) Amortization of prior service cost included in net loss 0.2 0.1 0.1 Amortization of net actuarial loss included in net loss 1.9 1.4 1.0 Foreign currency exchange rate changes and other (1.9 ) 3.5 3.0 Total other comprehensive income (loss) during period $ 28.5 $ (12.0 ) $ (2.0 ) Benefit Plan Investments Our benefit plan investment policies are set with specific consideration of return and risk requirements in relationship to the respective liabilities. Our plan assets in our Switzerland pension plans represent approximately 87 percent of our plan assets for these pension plans. Given the long-term nature of our liabilities, these plans have the flexibility to manage an above-average degree of risk in the asset portfolios. At the investment-policy level, there are no specifically prohibited investments. However, within individual investment manager mandates, restrictions and limitations are contractually set to align with our investment objectives, ensure risk control and limit concentrations. We manage our portfolio to minimize concentration of risk by allocating funds within asset categories. In addition, within a category we use different managers with various management objectives to eliminate any significant concentration of risk. The investment strategy is to diversify in four major categories with a designated percentage invested in each including 24% fixed income securities, 48% equity securities, a share of 11% in Real Estate Switzerland and 17% in other alternative investments (senior loans, hedge funds and insurance-linked securities). Each category is diversified and comprised of the following: • Fixed-income securities - Swiss Bonds, Global Aggregates, Global Aggregate Corporates and Emerging Markets Local Currencies. • Equity investments - Swiss Equities, World Equities MSCI, Low Volatility Equities (to reduce risk), Emerging Markets Equities and real estate investment trusts. • Real Estate in Switzerland - investment foundations and funds • Other investments - represents primarily private equity like investments, hedge funds, insurance-linked securities, cash and mark-to-market derivatives. We determine the fair value of the investments based on a market approach using quoted market values, significant other observable inputs for identical or comparable assets or liabilities, or discounted cash flow analysis for all investments except hedge funds, private equity-like investments and real estate. We determine the fair value of investments using the value reported by the partnership, adjusted for known cash flows and significant events through our reporting date. Values provided by the partnerships are primarily based on analysis of and judgments about the underlying investments. Inputs to these valuations include underlying NAVs, discounted cash flow valuations, comparable market valuations, and may also include adjustments for currency, credit, liquidity and other risks as applicable. The vast majority of these private partnerships provide us with annual financial statements including their compliance with fair valuation procedures consistent with applicable accounting standards. We determine the fair value of real estate investments based on the NAV provided by the fund manager. These NAVs are developed with inputs including discounted cash flow, independent appraisal and market comparable analyses. The fair values of these pension plan assets as of December 31, 2018 by asset category are as follows: Fair Value Measurements Using Asset Class Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Investments Valued at Net Asset Value (1) Public equity securities $ 2.2 $ 1.0 $ — $ — $ 1.2 Fixed income: Developed markets 29.9 7.8 0.1 — 22.0 Emerging markets 6.4 0.7 0.4 — 5.3 Private alternative investments: — Hedge funds 6.6 — — — 6.6 Equity-like funds 49.0 — — — 49.0 Real estate 20.1 0.1 — — 20.0 Other 17.4 0.3 2.3 — 14.8 Total $ 131.6 $ 9.9 $ 2.8 $ — $ 118.9 (1) Certain investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. No material transfers between Level 1, Level 2, or Level 3 occurred during the year ended December 31, 2018. The activity in the Level 3 investments during the year ended December 31, 2018 was not material. The fair values of these pension plan assets as of December 31, 2017 by asset category are as follows: Fair Value Measurements Using Asset Class Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Investments Valued at Net Asset Value (1) Public equity securities $ 0.8 $ 0.6 $ — $ — $ 0.2 Fixed income: Developed markets 29.9 8.2 0.1 — 21.6 Emerging markets 7.2 0.6 0.3 — 6.3 Private alternative investments: Hedge funds 6.8 — — — 6.8 Equity-like funds 52.7 — — — 52.7 Real estate 20.2 — — — 20.2 Other 13.9 0.1 0.1 13.7 Total $ 131.5 $ 9.5 $ 0.5 $ — $ 121.5 (1) Certain investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. No material transfers between Level 1, Level 2, or Level 3 occurred during the year ended December 31, 2017. The activity in the Level 3 investments during the year ended December 31, 2017 was not material. No contributions to these pension plans are expected in 2019. Retiree Health Benefit Plan There are two retiree health benefit plan where the plan liabilities that relate to our employees were legally required to transfer to Elanco at the time of separation from Lilly. The accrued retirement benefits for these plans were $3.9 million and $9.8 million as of December 31, 2018 and 2017, respectively. Defined Contribution Plans Lilly has defined contribution savings plans that include certain of our employees worldwide. The purpose of these plans is generally to provide additional financial security during retirement by providing employees with an incentive to save. Our contributions to the plans are based on our employee contributions and the level of our match. Expenses related to our employees under the plans totaled $20.9 million , $22.1 million and $19.6 million for the years ended December 31, 2018, 2017, and 2016, respectively.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share As discussed in Note 1, Elanco Parent was formed for the purpose of facilitating the IPO. Lilly held all shares of Elanco Parent from the time of formation until the IPO. Prior to IPO, there were an aggregate of 293,290,000 shares of our common stock held by Lilly (which represents the 100 shares held by Lilly prior to giving effect to the 2,932,900 -for-1 stock split that occurred on September 19, 2018). In connection with the completion of the IPO, an additional 72,335,000 shares of our common stock were issued. Earnings per share was calculated based on the weighted average shares outstanding during each period based on the assumption that the shares held by Lilly were outstanding for all periods prior to IPO.

Related Party Agreements and Tr

Related Party Agreements and Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Agreements and Transactions	Related Party Agreements and Transactions Transactions with Lilly Subsequent to Separation and Related to the Separation As described in Note 1, in connection with the Separation, Lilly transferred to us substantially all of its animal health businesses in exchange for approximately $4.2 billion . This is reflected as consideration to Lilly in our consolidated and combined statement of equity. The terms of our separation are covered by a master services agreement entered with Lilly (MSA). Under the terms of the MSA, through a series of transactions, Lilly transferred to us the businesses that will continue as part of Elanco. For a certain portion of our operations, the legal transfer of our net assets did not occur prior to the Separation due to certain regulatory requirements in each of these countries. Under the MSA entered into with Lilly, we are responsible for the business activities conducted by Lilly on our behalf and are subject to the risks and entitled to the benefits generated by these operations and assets. As a result, the related assets and liabilities and results of operations have been reported in our consolidated and combined financial statements. The total net assets associated with these jurisdictions are $95.6 million and the annual profits are insignificant. As of December 31, 2018, we have $202.7 million of restricted cash on our consolidated and combined balance sheet along with an offsetting Payable to Lilly, which reflects the cash that will be used to fund the purchase of the local country assets from Lilly. At the time of the IPO, we entered into a number of agreements related to ongoing activities between Elanco and Lilly including the following: • Transitional Services Agreement. Historically, Lilly has provided us significant shared services and resources related to corporate functions such as executive oversight, treasury, legal, finance, human resources, tax, internal audit, financial reporting, information technology and investor relations, which we refer to collectively as the "Lilly Services." Under the terms of the TSA, we will be able to use Lilly Services for a fixed term established on a service-by-service basis. We will pay Lilly mutually agreed-upon fees for the Lilly Services provided under the TSA, which will be based on Lilly's cost (including third-party costs) of providing the Lilly Services through March 31, 2021 , and subject to a mark-up of 7% thereafter, with additional inflation-based escalation beginning January 1, 2020 . The fees under the TSA become payable for all periods beginning after October 1, 2018 . • Intellectual Property and Technology License Agreement. We entered into an intellectual property and technology license agreement with Lilly immediately prior to the completion of the IPO. Under the intellectual property and technology license agreement, Lilly granted Elanco an exclusive, perpetual license to exploit products in the animal health field that utilize or use certain of Lilly's intellectual property (excluding trademarks). In addition, Lilly granted Elanco non-exclusive, non-sublicensable license to screen certain compounds in Lilly's compound libraries to exploit products in the animal use certain of Lilly's intellectual property. This screening license has an initial term of two years , subject to three one -year extensions, each of which requires Lilly's consent. We also entered into a tax matters agreement (TMA), an employee matters agreement, a toll manufacturing and supply agreement and a registration rights agreement with Lilly in connection with the Separation. Our consolidated and combined financial statement of operations includes revenue of $7.0 million related to a toll manufacturing arrangement and $28 million related to TSA charges. At December 31, 2018, we have a payable to Lilly of $66.0 million reflected in Payable to Lilly on our consolidated and combined balance sheet related to ongoing transactions with Lilly including those transactions described above and the reimbursement of certain costs Lilly incurred on our behalf during the period. Transactions with Lilly Prior to Separation Prior to IPO, we did not operate as a standalone business and had various relationships with Lilly whereby Lilly provided services to us. The impact on our historical combined financial statements includes the following: Transfers to/from Lilly, net As discussed in the basis of presentation, net parent company investment is primarily impacted by contributions from Lilly, which are the result of treasury activity and net funding provided by or distributed to Lilly. For the years ended December 31, 2018 , 2017 and 2016, the net transfers (to)/from Lilly were $(226.3) million , $873.3 million and ($129.2) million , respectively. The most significant activity impacting the 2017 transfer was the financing by Lilly of our acquisition in the amount of $882.1 million for Boehringer Ingelheim Vetmedica, Inc.'s United States feline, canine, and rabies vaccine portfolio and other related assets in 2017. Other activities that impacted the net transfers (to)/from Lilly include corporate overhead and other allocations, income taxes, retirement benefits, and centralized cash management. Corporate Overhead and Other Allocations Lilly provides us certain services, including executive oversight, treasury, legal, finance, human resources, tax, internal audit, financial reporting, information technology and investor relations. We provide Lilly certain services related to manufacturing support. Our financial statements reflect an allocation of these costs prior to IPO. When specific identification is not practicable, the remainder have been allocated primarily on a proportional cost method on a basis of revenue or headcount. The allocations of services from Lilly, prior to IPO, to us were reflected as follows in the combined statements of operations: 2018 (1) 2017 2016 Cost of sales $ 21.8 $ 31.8 $ 32.5 Research and development 2.2 2.8 2.3 Marketing, selling and administrative 81.2 117.1 110.5 Total $ 105.2 $ 151.7 $ 145.3 (1) Through September 30, 2018 We provide Lilly certain services related to manufacturing support. Allocations of manufacturing support from us to Lilly $3.7 million , $6.2 million and $5.5 million for the for the years ended December 31, 2018 , 2017 and 2016, respectively, reduced the cost of sales in the consolidated and combined statements of operations. The financial information herein may not necessarily reflect our consolidated financial position, results of operations and cash flows in the future or what they would have been if we had been a separate, standalone entity during the periods presented. Management believes that the methods used to allocate expenses are reasonable. Stock-based Compensation As discussed in Note 13, our employees participate in Lilly stock-based compensation plans, the costs of which have been allocated to us and recorded in cost of sales, research and development, and marketing, selling and administrative expenses in the consolidated and combined statements of operations. The costs of such plans related to our employees were $26.0 million , $25.0 million and $20.4 million for the year ended December 31, 2018 , 2017 and 2016, respectively. Retirement Benefits As discussed in Note 17, our employees participate in defined benefit pension and other post retirement plans sponsored by Lilly, the costs and benefits of which have been recorded in the consolidated and combined statement of operations in cost of sales, research and development, and marketing, selling and administrative expenses. the costs/(benefits) of such plans related to the Company's employees were $(6.3) million , $ 73.7 million and $11.3 million for the years ended December 31, 2018, 2017 and 2016, respectively. Centralized Cash Management Lilly uses a centralized approach to cash management and financing of operations. Until Separation, the majority of our business was party to Lilly’s cash pooling arrangements to maximize Lilly's availability of cash for general operating and investing purposes. Under these cash pooling arrangements, cash balances were swept regularly from our accounts prior to IPO. Cash transfers to and from Lilly’s cash concentration accounts and the resulting balances at the end of each reporting period were reflected in net parent company investment in the combined balance sheets. Debt Prior to IPO, Lilly’s third-party debt and the related interest expense were not allocated to us for any of the periods presented in the combined statement of operations and balance sheets as we were not the legal obligor of the debt and Lilly borrowings were not directly attributable to our business. Other Related Party Transactions We sell certain products to and receive certain goods and services from a customer/vendor, whose chairman and Chief Executive Officer is a member of Lilly's Board of Directors. These product sales resulted in revenue of $23.5 million , $24.8 million and $14.3 million for the years ended December 31, 2018 , 2017 and 2016, respectively. The product sales resulted in accounts receivable of $2.5 million and $2.0 million at December 31, 2018 and 2017, respectively. The purchase of goods and services resulted in cost of sales and operating expenses of $3.9 million , $5.9 million and $7.1 million for the years ended December 31, 2018 , 2017 and 2016, respectively. The purchase of goods and services resulted in accounts payable of $0.7 million and $0.4 million at December 31, 2018 and 2017, respectively.

Selected Quarterly Data (unaudi

Selected Quarterly Data (unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Data (unaudited)	Selected Quarterly Data (unaudited) 2018 Fourth Third Second First Revenue $ 799.3 $ 761.1 $ 770.2 $ 736.2 Cost of sales 412.5 369.8 431.5 360.0 Operating expenses (1) 246.2 237.9 252.5 245.2 Asset Impairment, restructuring, and other special charges 46.0 12.4 68.0 2.4 Interest expense, net of capitalized interest 21.0 8.6 — — Income (loss) before income taxes (2.2 ) 78.8 (40.0 ) 77.5 Income taxes (18.6 ) 18.6 22.8 4.8 Net income (loss) 16.4 60.2 (62.8 ) 72.7 Earnings (loss) per share—basic and diluted 0.04 0.20 (0.21 ) 0.25 2017 Fourth Third Second First Revenue $ 754.3 $ 697.1 $ 732.8 $ 704.8 Cost of sales 405.0 376.2 374.0 338.6 Operating expenses (1) 258.8 256.6 257.8 258.3 Asset Impairment, restructuring, and other special charges 185.8 23.7 58.8 106.8 Interest expense, net of capitalized interest — — — — Income (loss) before income taxes (155.4 ) (9.1 ) (15.2 ) (52.9 ) Income taxes 6.1 11.6 15.0 45.4 Net income (loss) (161.5 ) (20.7 ) (30.2 ) (98.3 ) Earnings (loss) per share—basic and diluted (0.55 ) (0.07 ) (0.10 ) (0.34 ) (1) Includes research and development and marketing, selling, and administrative expenses.

Basis of Presentation (Policies

Basis of Presentation (Policies)	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	The accompanying consolidated and combined financial statements have been prepared in accordance with accounting principles generally accepted in the United States (GAAP). The accounts of all wholly-owned and majority-owned subsidiaries are included in the consolidated financial statements. All intercompany balances and transactions have been eliminated. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, expenses, and related disclosures at the date of the financial statements and during the reporting period. Actual results could differ from those estimates. We issued our financial statements by filing with the Securities and Exchange Commission and have evaluated subsequent events up to the time of the filing.
Reclassifications	During the period ended December 31, 2018, certain combined balance sheet amounts related to the prior year have been revised to correct the sales rebates and discounts liability, which did not correctly reflect an accrual for rebates related to product held in the wholesalers' pipeline. In accordance with Securities and Exchange Commission Staff Accounting Bulletin No. 99, Materiality , and Accounting Standards Codification (ASC) 250, Presentation of Financial Statements , we assessed the materiality of this correction and concluded that the accrual for the rebate related to product held in the wholesalers' pipeline was not material to prior periods, and therefore, amendments of previously filed reports are not required.
Consolidation	For the periods after separation, the financial statements are prepared on a consolidated basis and reflect the results of operations, comprehensive income, financial position, equity and cash flows resulting from our operations as an independent company. For periods prior to the Separation, our financial statements are combined, have been prepared on a standalone basis, and are derived from Lilly's consolidated financial statements and accounting records. The consolidated and combined financial statements reflect the financial position, results of operations and cash flows related to the animal health businesses that were transferred to Elanco Parent and are prepared in conformity with GAAP. The combined financial statements include the attribution of certain assets and liabilities that historically have been held at the Lilly corporate level but which are specifically identifiable or attributable to the businesses that have been transferred to Elanco Parent. All intercompany transactions and accounts within Elanco have been eliminated. All transactions between us and Lilly are considered to be effectively settled in the combined financial statements at the time the intercompany transaction is recorded. The total net effect of the settlement of these intercompany transactions is reflected in the combined statements of cash flows as a financing activity and in the combined balance sheets as net parent company investment.
Expenses Related to Certain Corporate Functions	Prior to the separation, these combined financial statements include an allocation of expenses related to certain Lilly corporate functions, including executive oversight, treasury, legal, finance, human resources, tax, internal audit, financial reporting, information technology and investor relations, prior to IPO. These expenses have been allocated to us based on direct usage or benefit where specifically identifiable, with the remainder allocated primarily on a pro rata basis of revenue, headcount and other measures. We consider the expenses methodology and results to be reasonable for all periods presented. However, the allocations may not be indicative of the actual expense that would have been incurred had we operated as an independent, publicly traded company for the periods presented. It is impractical to estimate what the standalone costs of Elanco would have been in the historical periods. After the separation, a TSA between Lilly and Elanco went into effect. Under the terms of the TSA, we will be able to use Lilly Services for a fixed term established on a service-by-service basis. We are paying Lilly mutually agreed upon fees for the Lilly Services provided under the TSA. Our consolidated and combined financial statements reflect the charges for Lilly Services after the IPO. See Note 19 for additional details.
Income Tax	he income tax amounts in the combined financial statements have been calculated based on a separate return methodology and presented as if our operations were separate taxpayers in the respective jurisdictions. We file income tax returns in the United States (U.S.) federal jurisdiction and various state, local and non-U.S. jurisdictions. Certain of these income tax returns are filed on a consolidated or combined basis with Eli Lilly and Company and/or its subsidiaries.
Benefit and Combined Stock-Based Compensation Plans	Lilly maintains various benefit and combined stock-based compensation plans at a corporate level and other benefit plans at a country level. Our employees participate in such programs and the portion of the cost of those plans related to our employees is included in our financial statements. However, the consolidated and combined balance sheets do not include any equity issued related to stock-based compensation plans or any net benefit plan obligations unless the benefit plan covers only our dedicated employees or where the legal obligation associated with the benefit plan will transfer to Elanco.
Equity Balance	Prior to Separation, the equity balance in the combined financial statements represents the excess of total assets over liabilities, including intercompany balances between us and Lilly (net parent company investment) and accumulated other comprehensive loss. Net parent company investment is primarily impacted by contributions from Lilly which are the result of treasury activities and net funding provided by or distributed to Lilly.
Revenue recognition	We recognize revenue from sales of products at the time title of goods passes to the buyer and the buyer assumes the risks and rewards of ownership. Provisions for returns, discounts and rebates are established in the same period the related sales are recognized. For arrangements with contract manufacturing organizations (CMO), we recognize revenue over time or at a point in time depending on its evaluation of when the customer obtains control of the promised goods or service. Revenue is recognized over time when we are creating or enhancing an asset that the customer controls as the asset is created or enhanced or our performance does not create an asset with an alternative use and we have an enforceable right to payment for performance completed.
Research and development expenses and acquired in-process research and development	Research and development expenses include the following: • Research and development costs, which are expensed as incurred. • Milestone payment obligations incurred prior to regulatory approval of the product, which are accrued when the event requiring payment of the milestone occurs. • Acquired in-process research and development (IPR&D) expense, which includes the initial costs of IPR&D projects, acquired directly in a transaction other than a business combination that do not have an alternative future use.
Foreign Currency Translation	Operations in our subsidiaries outside the United States (U.S.) are recorded in the functional currency of each subsidiary which is determined by a review of the environment where each subsidiary primarily generates and expends cash. The results of operations for our subsidiaries outside the U.S. are translated from functional currencies into U.S. dollars using the weighted average currency rate for the period. Assets and liabilities are translated using the period end exchange rates. The U.S. dollar effects that arise from translating the net assets of these subsidiaries are recorded in other comprehensive income (loss).
Implementation of New Financial Accounting Pronouncements	The following table provides a brief description of accounting standards that were effective January 1, 2018 and were adopted on that date: Standard Description Effect on the financial statements or other significant matters Accounting Standards Update 2014-09 and various other related updates, Revenue from Contracts with Customers This standard replaced existing revenue recognition standards and requires entities to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. An entity can apply the new revenue standard retrospectively to each prior reporting period presented or with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. We applied the latter approach. Application of the new standard to applicable contracts had no impact to net parent company investment as of January 1, 2018. Disclosures required by the new standard are included in Note 5. Accounting Standards Update 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory This standard requires entities to recognize the income tax consequences of intra-entity transfers of assets other than inventory at the time of transfer. This standard requires a modified retrospective approach to adoption. Upon adoption, the cumulative effect of applying the standard resulted in a decrease to net parent company investment of approximately $0.3 million. Adoption of this standard did not result in a material change in net income for the twelve months ended December 31, 2018. Accounting Standards Update 2017-07, Compensation-Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This standard was issued to improve the transparency and comparability among organizations by requiring entities to separate their net periodic pension cost and net periodic postretirement benefit cost into a service cost component and other components. Previously, the costs of the other components along with the service cost component were classified based upon the function of the employee. This standard requires entities to classify the service cost component in the same financial statement line item or items as other compensation costs arising from services rendered by pertinent employees. The other components of net benefit cost are now presented separately from the line items that include the service cost component. When applicable, the service cost component is now the only component eligible for capitalization. An entity should apply the new standard retrospectively for the classification of the service cost and other components and prospectively for the capitalization of the service cost component. Upon adoption of this standard, pension and postretirement benefit cost components other than service costs are presented in other (income) expense, net. Retrospective application was not material to the combined statement of operations for the twelve months ended December 31, 2017. We do not expect application of the new standard to have a material impact on an ongoing basis. Accounting Standards Update 2017-12, Derivatives and Hedging This standard amends the hedge accounting recognition and presentation requirements and is intended to better align hedge accounting with companies' risk management strategies. This standard eliminates the requirements to separately measure and report hedge ineffectiveness and generally requires that the entire change in fair value of a hedging instrument be presented in the same income statement line item as the respective hedged item. The standard also modifies certain disclosure requirements. We elected to early adopt this guidance as of January 1, 2018. There were no hedging contracts in effect as of the date of adoption. We do not expect application of the new standard to have a material impact on an ongoing basis. The following table provides a brief description of the accounting standard that has not yet been adopted and could have a material effect on the consolidated financial statements: Standard Description Effective Date Effect on the financial statements or other significant matters Accounting Standards Update 2016-02, Leases This standard was issued to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities, including leases classified as operating leases under current GAAP, on the balance sheet and requiring additional disclosures about leasing arrangements. An entity can apply the new leases standard retrospectively to each prior reporting period presented or with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. We plan to use the latter approach. This standard is effective January 1, 2019, with early adoption permitted. We intend to adopt this standard on that date. We expect to record a right-of-use asset and lease liability for operating leases of approximately $75-95 million on our consolidated balance sheet on January 1, 2019. Our accounting for capital leases will remain substantially unchanged. This standard will not have a material impact on our consolidated statement of operations.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Description of Accounting Standards Adopted and Not Yet Adopted	The following table provides a brief description of accounting standards that were effective January 1, 2018 and were adopted on that date: Standard Description Effect on the financial statements or other significant matters Accounting Standards Update 2014-09 and various other related updates, Revenue from Contracts with Customers This standard replaced existing revenue recognition standards and requires entities to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. An entity can apply the new revenue standard retrospectively to each prior reporting period presented or with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. We applied the latter approach. Application of the new standard to applicable contracts had no impact to net parent company investment as of January 1, 2018. Disclosures required by the new standard are included in Note 5. Accounting Standards Update 2016-16, Income Taxes: Intra-Entity Transfers of Assets Other Than Inventory This standard requires entities to recognize the income tax consequences of intra-entity transfers of assets other than inventory at the time of transfer. This standard requires a modified retrospective approach to adoption. Upon adoption, the cumulative effect of applying the standard resulted in a decrease to net parent company investment of approximately $0.3 million. Adoption of this standard did not result in a material change in net income for the twelve months ended December 31, 2018. Accounting Standards Update 2017-07, Compensation-Retirement Benefits: Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost This standard was issued to improve the transparency and comparability among organizations by requiring entities to separate their net periodic pension cost and net periodic postretirement benefit cost into a service cost component and other components. Previously, the costs of the other components along with the service cost component were classified based upon the function of the employee. This standard requires entities to classify the service cost component in the same financial statement line item or items as other compensation costs arising from services rendered by pertinent employees. The other components of net benefit cost are now presented separately from the line items that include the service cost component. When applicable, the service cost component is now the only component eligible for capitalization. An entity should apply the new standard retrospectively for the classification of the service cost and other components and prospectively for the capitalization of the service cost component. Upon adoption of this standard, pension and postretirement benefit cost components other than service costs are presented in other (income) expense, net. Retrospective application was not material to the combined statement of operations for the twelve months ended December 31, 2017. We do not expect application of the new standard to have a material impact on an ongoing basis. Accounting Standards Update 2017-12, Derivatives and Hedging This standard amends the hedge accounting recognition and presentation requirements and is intended to better align hedge accounting with companies' risk management strategies. This standard eliminates the requirements to separately measure and report hedge ineffectiveness and generally requires that the entire change in fair value of a hedging instrument be presented in the same income statement line item as the respective hedged item. The standard also modifies certain disclosure requirements. We elected to early adopt this guidance as of January 1, 2018. There were no hedging contracts in effect as of the date of adoption. We do not expect application of the new standard to have a material impact on an ongoing basis. The following table provides a brief description of the accounting standard that has not yet been adopted and could have a material effect on the consolidated financial statements: Standard Description Effective Date Effect on the financial statements or other significant matters Accounting Standards Update 2016-02, Leases This standard was issued to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities, including leases classified as operating leases under current GAAP, on the balance sheet and requiring additional disclosures about leasing arrangements. An entity can apply the new leases standard retrospectively to each prior reporting period presented or with the cumulative effect of initially applying the standard recognized at the date of initial application in retained earnings. We plan to use the latter approach. This standard is effective January 1, 2019, with early adoption permitted. We intend to adopt this standard on that date. We expect to record a right-of-use asset and lease liability for operating leases of approximately $75-95 million on our consolidated balance sheet on January 1, 2019. Our accounting for capital leases will remain substantially unchanged. This standard will not have a material impact on our consolidated statement of operations.

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Summary of Activity in Sales Rebates and Discounts Liability	The following table summarizes the activity in the sales rebates and discounts liability in the U.S.: Year Ended December 31, 2018 2017 Beginning balance $ 114.8 $ 116.1 Reduction of revenue 221.0 236.1 Payments (217.3 ) (237.4 ) Ending balance $ 118.5 $ 114.8
Disaggregation of Revenue	The following table summarizes our revenue disaggregated by product category for the years ended December 31: 2018 2017 2016 Companion Animal Disease Prevention $ 804.6 $ 660.2 $ 628.4 Companion Animal Therapeutics 283.1 260.8 255.6 Food Animal Future Protein & Health 711.2 649.2 630.8 Food Animal Ruminants Swine 1,174.0 1,175.0 1,309.2 Other 93.9 143.8 89.5 Total Revenue $ 3,066.8 $ 2,889.0 $ 2,913.5

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Summary of Amounts Recognized for Assets Acquired and Liabilities Assumed	The following table summarizes the amounts recognized for assets acquired and liabilities assumed as of the acquisition date: Estimated Fair Value at April 22, 2016 Deferred tax assets $ 15.3 Acquired in-process research and development 31.6 Marketed products(1) 57.0 Deferred tax liabilities (15.3 ) Total consideration 88.6 Less: Contingent consideration (43.6 ) Total cash paid $ 45.0 (1) These intangible assets, which are being amortized on a straight-line basis over their estimated useful lives, were expected to have a weighted average useful life of 20 years . The following table summarizes the amounts recognized for assets acquired and liabilities assumed as of the acquisition date: Estimated Fair Value at January 3, 2017 Inventories (1) $ 108.6 Marketed products (2) 297.0 Property and equipment 148.2 Other assets and liabilities — net 8.2 Total identifiable net assets 562.0 Goodwill (3) 320.1 Total consideration transferred — net of cash acquired $ 882.1 (1) The fair value for inventories include a purchase accounting adjustment to write up the inventory value, which resulted in incremental cost of sales of $42.7 million in 2017. The fair value was determined by estimating the expected sales price of the inventories, reduced for all costs expected to the incurred and a profit on those costs. (2) These intangible assets, which are being amortized on a straight-line basis over their estimated useful lives, were expected to have a weighted average useful life of 10 years . (3) The goodwill recognized from this acquisition is attributable primarily to expected synergies from combining the operations of BIVIVP with our legacy business, future unidentified projects and products, and the assembled workforce of BIVIVP. The goodwill associated with this acquisition is deductible for tax purposes.

Asset Impairment, Restructuri_2

Asset Impairment, Restructuring and Other Special Charges (Tables)	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Total Charges Related to Asset Impairment, Restructuring and Other Special Charges	The Company's total charges related to asset impairment, restructuring and other special charges, including integration of acquired businesses, in our consolidated and combined statements of operations consisted of the following for the years ended December 31: 2018 2017 2016 Cash expense: Severance and other $ 15.5 $ 162.0 $ 42.1 Integration 26.5 90.3 154.8 Facility exit costs 5.7 31.8 13.2 Total cash expense 47.7 284.1 210.1 Non-cash expense: Asset impairment 81.9 110.6 98.3 Total non-cash expense 81.9 110.6 98.3 Gain on sale of fixed assets (0.8 ) (19.6 ) — Total expense $ 128.8 $ 375.1 $ 308.4
Summary of Activity in Reserves	The following table summarizes the activity in our reserves established in connection with these restructuring activities: Exit costs Severance Total Balance at December 31, 2016 $ 11.5 $ 26.6 $ 38.1 Charges 31.8 162.0 193.8 Reserve adjustment 1.4 (3.9 ) (2.5 ) Cash paid (9.8 ) (141.6 ) (151.4 ) Balance at December 31, 2017 34.9 43.1 78.0 Charges 11.7 15.5 27.2 Separation adjustment (5.9 ) — (5.9 ) Reserve adjustment (6.0 ) — (6.0 ) Cash paid (25.4 ) (23.5 ) (48.9 ) Balance at December 31, 2018 $ 9.3 $ 35.1 $ 44.4

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2018
Inventory Disclosure [Abstract]
Schedule of Inventories	Inventories at December 31 consisted of the following: 2018 2017 Finished products $ 400.7 $ 452.0 Work in process 570.4 580.0 Raw materials and supplies 80.4 70.4 Total (approximates replacement cost) 1,051.5 1,102.4 Decrease to LIFO cost (47.4 ) (40.1 ) Inventories $ 1,004.1 $ 1,062.3

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long-term debt as of December 31, 2018 consisted of the following: December 31, 2018 Term credit facility $ 492.5 3.912% Senior Notes due 2021 500.0 4.272% Senior Notes due 2023 750.0 4.900% Senior Notes due 2028 750.0 Other obligations 0.5 Unamortized debt issuance costs (20.7 ) 2,472.3 Less current portion of long-term debt (29.0 ) Total long-term debt $ 2,443.3

Financial Instruments and Fai_2

Financial Instruments and Fair Value (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Summary of Fair Value Information	The following table summarizes the fair value information at December 31, 2018 and 2017 for contingent consideration liabilities and net investment hedge liability measured at fair value on a recurring basis in the respective balance sheet line items: Fair Value Measurements Using Financial statement line item Carrying Amount Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value December 31, 2018 Other current liabilities- contingent consideration $ 5.1 $ — $ — $ 5.1 $ 5.1 Other noncurrent liabilities- contingent consideration 69.0 — — 69.0 69.0 Other noncurrent liabilities- cross currency interest rate contracts designated as net investment hedges 7.4 — 7.4 — 7.4 December 31, 2017 Other current liabilities- contingent consideration 1.3 — — 1.3 1.3 Other noncurrent liabilities- contingent consideration 45.2 — — 45.2 45.2

Goodwill and Intangibles (Table

Goodwill and Intangibles (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Components of Finite-Lived Intangible Assets	The components of intangible assets other than goodwill at December 31 were as follows: 2018 2017 Description Carrying Amount, Gross Accumulated Amortization Carrying Amount, Net Carrying Amount, Gross Accumulated Amortization Carrying Amount, Net Finite-lived intangible assets: Marketed products $ 3,193.5 $ (779.2 ) $ 2,414.3 $ 3,151.2 $ (599.8 ) $ 2,551.4 Other 53.1 (34.0 ) 19.1 54.1 (29.9 ) 24.2 Total finite-lived intangible assets 3,246.6 (813.2 ) 2,433.4 3,205.3 (629.7 ) 2,575.6 Indefinite-lived intangible assets: Acquired in-process research and development 19.6 — 19.6 97.2 — 97.2 Other intangibles $ 3,266.2 $ (813.2 ) $ 2,453.0 $ 3,302.5 $ (629.7 ) $ 2,672.8
Components of Indefinite-Lived Intangible Assets	The components of intangible assets other than goodwill at December 31 were as follows: 2018 2017 Description Carrying Amount, Gross Accumulated Amortization Carrying Amount, Net Carrying Amount, Gross Accumulated Amortization Carrying Amount, Net Finite-lived intangible assets: Marketed products $ 3,193.5 $ (779.2 ) $ 2,414.3 $ 3,151.2 $ (599.8 ) $ 2,551.4 Other 53.1 (34.0 ) 19.1 54.1 (29.9 ) 24.2 Total finite-lived intangible assets 3,246.6 (813.2 ) 2,433.4 3,205.3 (629.7 ) 2,575.6 Indefinite-lived intangible assets: Acquired in-process research and development 19.6 — 19.6 97.2 — 97.2 Other intangibles $ 3,266.2 $ (813.2 ) $ 2,453.0 $ 3,302.5 $ (629.7 ) $ 2,672.8
Estimated Amortization Expense	The estimated amortization expense for each of the next five years associated with our finite-lived intangible assets as of December 31, 2018 is as follows: 2019 2020 2021 2022 2023 Estimated amortization expense $ 197.9 $ 198.3 $ 198.0 $ 196.0 $ 195.8

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property and Equipment and Depreciation Expense	At December 31, property and equipment consisted of the following: 2018 2017 Land $ 27.6 $ 25.1 Buildings 567.2 557.7 Equipment 1,025.1 994.5 Construction in progress 181.1 177.1 1,801 1,754.4 Less accumulated depreciation (878.6 ) (834.1 ) Property and equipment, net $ 922.4 $ 920.3 Depreciation expense related to property and equipment and rental expense for all leases was as follows: 2018 2017 2016 Depreciation expense $ 81.3 $ 79.8 $ 75.7 Rental expense 47.5 47.1 41.8
Rental Expense for All Leases	Depreciation expense related to property and equipment and rental expense for all leases was as follows: 2018 2017 2016 Depreciation expense $ 81.3 $ 79.8 $ 75.7 Rental expense 47.5 47.1 41.8
Future Minimum Rental Commitments	The future minimum rental commitments under non-cancelable operating leases are as follows: 2019 2020 2021 2022 2023 After 2023 Lease commitments $ 25.2 $ 20.1 $ 13.5 $ 10.0 $ 8.3 $ 18.5

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Assumptions Used	The weighted-average fair values of the SVA units granted during the years ended December 31, 2018, 2017 and 2016 were $49.38 , $66.25 and $48.68 , respectively, determined using the following assumptions: (Percents) 2018 2017 2016 Expected dividend yield 2.50 % 2.50 % 2.00 % Risk-free interest rate 2.31 1.38 0.92 Volatility 22.26 22.91 21.68 The fair-value-based method for valuing each Elanco stock option grant on the grant date uses the Black-Scholes-Merton option-pricing model, which incorporates a number of valuation assumptions noted in the following table, shown at their weighted-average values for the year ended December 31: 2018 Expected dividend yield (1) 0.70 % Risk-free interest rate (2) 3.07 % Expected stock price volatility (3) 28.25 % Expected term (4) (years) 6.5 (1) Determined using the expected quarterly dividend divided by the available three-month average stock price as of the valuation date, annualized and continuously compounded. (2) Determined using the term-matched, zero-coupon risk-free rate from the Treasury Constant Maturity yield curve, continuously compounded (3) Determined using a leverage-adjusted historical volatility of peer companies (4) Determined using SEC safe harbor approach, based on a 3 -year cliff vesting schedule and 10 -year contractual term.
Schedule of Stock Option Activity	Stock option activity during the year ended December 31, 2018 is summarized below: Shares of Common Stock Attributable to Options Weighted-Average Exercise Price of Options Outstanding at January 1, 2018 — $ — Granted 421,297 31.61 Exercised — — Forfeited or expired — — Outstanding at December 31, 2018 421,297 31.61 Exercisable at December 31, 2018 58,766 31.61 As of December 31, 2018, the weighted-average remaining contractual term of the exercisable options was 9.8 years and the aggregate intrinsic value was $0.08 .

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Composition of Income (Loss) Before Income Tax Expense (Benefit)	Following is the composition of income (loss) before income tax expense (benefit): 2018 2017 2016 Federal $ 12.2 $ (133.2 ) $ (12.5 ) Foreign 101.9 (99.4 ) (9.9 ) Income (loss) before income taxes $ 114.1 $ (232.6 ) $ (22.4 )
Composition of Income Tax Expense (Benefit)	Following is the composition of income tax expense (benefit): 2018 2017 2016 Current: Federal $ 45.1 $ — $ — Foreign 45.5 91.6 31.1 State (2.3 ) (0.1 ) 0.3 Total current tax expense 88.3 91.5 31.4 Deferred: Federal (56.8 ) 42.6 18.4 Foreign (5.6 ) (16.6 ) (26.8 ) State 1.7 (6.3 ) 2.5 2017 Tax Act — (33.1 ) — Total deferred tax benefit (60.7 ) (13.4 ) (5.9 ) Income taxes $ 27.6 $ 78.1 $ 25.5
Significant Components of Deferred Tax Assets and Liabilities	Significant components of our deferred tax assets and liabilities as of December 31 are as follows: 2018 2017 Deferred tax assets: Compensation and benefits $ 32.2 $ 34.8 Accruals and reserves 47.8 12.0 Tax credit carryovers 1.9 19.2 Tax loss carryovers 21.7 144.9 Other 23.5 26.6 Total gross deferred tax assets 127.1 237.5 Valuation allowances (21.4 ) (127.7 ) Total deferred tax assets 105.7 109.8 Deferred tax liabilities: Intangibles (130.8 ) (165.2 ) Property and equipment (50.8 ) (43.1 ) Other (2.7 ) (7.4 ) Total deferred tax liabilities (184.3 ) (215.7 ) Deferred tax liabilities - net $ (78.6 ) $ (105.9 )
Movements in the Valuation Allowance	The movements in the valuation allowance are as follows: 2018 2017 January 1 $ (127.7 ) $ (39.1 ) Adjustment related to Separation 110.4 — January 1 (17.3 ) (39.1 ) Increase (5.8 ) (97.4 ) Release 1.7 8.8 December 31 $ (21.4 ) $ (127.7 )
Cash Payments of Income Taxes	Cash payments of income taxes were as follows: 2018 2017 2016 Cash payments of income taxes $ 26.9 $ 35.7 $ 53.6
Reconciliation of Income Tax Expense (Benefit)	The following is a reconciliation of the income tax expense (benefit) applying the U.S. federal statutory rate to income before income taxes to reported income tax expense: 2018 2017 2016 Income tax at the U.S. federal statutory tax rate $ 24.0 $ (81.4 ) $ (7.8 ) Add (deduct): International operations and change in foreign tax rates 11.5 55.6 8.4 State taxes 4.4 5.4 2.8 Income tax credits (17.3 ) (1.8 ) (1.7 ) Foreign inclusion items 9.0 4.2 2.4 IPO and separation costs 2.3 — — Other permanent adjustments 0.9 1.6 0.2 Change in uncertain tax positions (1.7 ) 6.2 5.2 Change in valuation allowance (1.7 ) 122.2 18.1 2017 Tax Act — (33.1 ) — Other (3.8 ) (0.8 ) (2.1 ) Income taxes $ 27.6 $ 78.1 $ 25.5
Reconciliation of Gross Unrecognized Tax Benefits	A reconciliation of the beginning and ending amount of gross unrecognized tax benefits is as follows: 2018 2017 2016 Beginning balance at January 1 $ 29.6 $ 25.7 $ 25.5 Adjustments related to Separation (17.6 ) — — Beginning balance at January 1 12.0 25.7 25.5 Additions based on tax positions related to the current year 2.2 7.9 7.4 Additions for tax positions of prior years 4.0 — — Settlements (3.0 ) (4.0 ) (7.1 ) Changes related to the impact of foreign currency translation (0.5 ) — (0.1 ) Ending balance at December 31 $ 14.7 $ 29.6 $ 25.7
Income Tax Expense (Benefit) Related to Interest and Penalties	2018 2017 2016 Income tax expense (benefit) $ (2.5 ) $ 2.5 $ 5.5

Geographic Information (Tables)

Geographic Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Revenue by Selected Geographic Area Information	Selected geographic area information was as follows: 2018 2017 2016 Geographic Information Revenue — to unaffiliated customers (1) : United States $ 1,483.2 $ 1,373.0 $ 1,361.6 International 1,583.6 1,516.0 1,551.9 Revenue $ 3,066.8 $ 2,889.0 $ 2,913.5 Long-lived assets (2) : United States $ 602.6 $ 604.7 $ 463.8 United Kingdom 187.5 204.4 190.6 Other foreign countries 195.8 190.2 173.0 Long-lived assets $ 985.9 $ 999.3 $ 827.4 (1) Revenue is attributed to the countries based on the location of the customer. (2) Long-lived assets consist of property and equipment, net, and certain noncurrent assets.
Long-lived Assets by Selected Geographic Area Information	Selected geographic area information was as follows: 2018 2017 2016 Geographic Information Revenue — to unaffiliated customers (1) : United States $ 1,483.2 $ 1,373.0 $ 1,361.6 International 1,583.6 1,516.0 1,551.9 Revenue $ 3,066.8 $ 2,889.0 $ 2,913.5 Long-lived assets (2) : United States $ 602.6 $ 604.7 $ 463.8 United Kingdom 187.5 204.4 190.6 Other foreign countries 195.8 190.2 173.0 Long-lived assets $ 985.9 $ 999.3 $ 827.4 (1) Revenue is attributed to the countries based on the location of the customer. (2) Long-lived assets consist of property and equipment, net, and certain noncurrent assets.

Retirement Benefits (Tables)

Retirement Benefits (Tables)	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Change in Benefit Obligation, Change in Plan Assets, and Funded Status	We use a measurement date of December 31 to develop the change in benefit obligation, change in plan assets, funded status and amounts recognized in the combined balance sheets at December 31 for our defined benefit pension plans, which were as follows: 2018 2017 Change in benefit obligation: Benefit obligation at beginning of year $ 258.6 $ 225.0 Service cost 11.3 10.5 Interest cost 2.5 1.8 Actuarial (gain) loss (44.7 ) 24.4 Benefits paid (2.7 ) (18.5 ) Foreign currency exchange rate changes and other adjustments 9.8 15.4 Benefit obligation at end of year 234.8 258.6 Change in plan assets: Fair value of plan assets at beginning of year 131.5 123.7 Actual return on plan assets (10.2 ) 13.3 Employer contribution 5.7 3.9 Benefits paid (2.7 ) (18.5 ) Foreign currency exchange rate changes and other adjustments 7.3 9.1 Fair value of plan assets at end of year 131.6 131.5 Funded status (103.2 ) (127.1 ) Unrecognized net actuarial loss 0.5 29.1 Unrecognized prior service cost 0.8 0.7 Net amount recognized $ (101.9 ) $ (97.3 )
Amounts Recognized in Combined Balance Sheet	Amounts recognized in the combined balance sheet consisted of: Noncurrent assets $ 2.3 $ 2.4 Other current liabilities (0.3 ) (0.3 ) Accrued retirement benefits (105.2 ) (129.2 ) Accumulated other comprehensive loss before income taxes 1.3 29.8 Net amount recognized $ (101.9 ) $ (97.3 )
Components of Accumulated Other Comprehensive Loss to be Recognized over Next Fiscal Year	During 2019, we expect the following components of accumulated other comprehensive loss to be recognized as components of net periodic benefit cost: Unrecognized net actuarial loss $ 0.5 Unrecognized prior service cost 0.8 Total $ 1.3
Weighted-Average Assumptions Related to Pension Plans	The following represents our weighted-average assumptions related to these pension plans as of December 31: (Percents) 2018 2017 2016 Discount rate for benefit obligation 1.5% 1.1% 1.0% Discount rate for net benefit costs 1.1 1.0 1.0 Rate of compensation increase for benefit obligation 2.2 2.1 3.1 Rate of compensation increase for net benefit costs 2.1 3.1 3.0 Expected return on plan assets for net benefit costs 4.0 4.4 4.9
Schedule of Expected Benefit Payments	The following benefit payments, which reflect expected future service, as appropriate, are expected to be paid as follows: 2019 2020 2021 2022 2023 2024-2028 Benefit payments $ 5.8 $ 6.4 $ 7.1 $ 6.1 $ 6.3 $ 35.9
Projected Benefit Obligations in Excess of Plan Assets	Amounts relating to these pension plans with projected benefit obligations in excess of plan assets were as follows at December 31: 2018 2017 Projected benefit obligation $ 229.2 $ 251.6 Fair value of plan assets 124.1 121.8
Accumulated Benefit Obligations in Excess of Plan Assets	Amounts relating to these defined benefit pension plans with accumulated benefit obligations in excess of plan assets were as follows at December 31: 2018 2017 Accumulated benefit obligation $ 194.3 $ 223.1 Fair value of plan assets 124.1 121.8
Net Pension Expense	Net pension expense related to these plans included the following components: 2018 2017 2016 Service cost $ 11.3 $ 10.5 $ 9.3 Interest cost 2.5 1.8 1.8 Expected return on plan assets (6.2 ) (2.4 ) (3.4 ) Amortization of prior service cost 0.2 0.1 0.1 Amortization of net actuarial loss 1.9 1.4 1.0 Other 0.5 — — Net pension expense $ 10.2 $ 11.4 $ 8.8
Amounts Recognized in Other Comprehensive Loss	The following represents the amounts recognized for these plans in other comprehensive loss: 2018 2017 2016 Actuarial gain (loss) arising during period $ 28.3 $ (17.0 ) $ (6.1 ) Amortization of prior service cost included in net loss 0.2 0.1 0.1 Amortization of net actuarial loss included in net loss 1.9 1.4 1.0 Foreign currency exchange rate changes and other (1.9 ) 3.5 3.0 Total other comprehensive income (loss) during period $ 28.5 $ (12.0 ) $ (2.0 )
Fair Value of Pension Plan Assets	The fair values of these pension plan assets as of December 31, 2017 by asset category are as follows: Fair Value Measurements Using Asset Class Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Investments Valued at Net Asset Value (1) Public equity securities $ 0.8 $ 0.6 $ — $ — $ 0.2 Fixed income: Developed markets 29.9 8.2 0.1 — 21.6 Emerging markets 7.2 0.6 0.3 — 6.3 Private alternative investments: Hedge funds 6.8 — — — 6.8 Equity-like funds 52.7 — — — 52.7 Real estate 20.2 — — — 20.2 Other 13.9 0.1 0.1 13.7 Total $ 131.5 $ 9.5 $ 0.5 $ — $ 121.5 (1) Certain investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair values of these pension plan assets as of December 31, 2018 by asset category are as follows: Fair Value Measurements Using Asset Class Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Investments Valued at Net Asset Value (1) Public equity securities $ 2.2 $ 1.0 $ — $ — $ 1.2 Fixed income: Developed markets 29.9 7.8 0.1 — 22.0 Emerging markets 6.4 0.7 0.4 — 5.3 Private alternative investments: — Hedge funds 6.6 — — — 6.6 Equity-like funds 49.0 — — — 49.0 Real estate 20.1 0.1 — — 20.0 Other 17.4 0.3 2.3 — 14.8 Total $ 131.6 $ 9.9 $ 2.8 $ — $ 118.9 (1) Certain investments that are measured at fair value using the NAV per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy.

Related Party Agreements and _2

Related Party Agreements and Transactions (Tables)	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Amounts Reflected in Consolidated and Combined Financial Statement of Operations and Allocations of Services	The allocations of services from Lilly, prior to IPO, to us were reflected as follows in the combined statements of operations: 2018 (1) 2017 2016 Cost of sales $ 21.8 $ 31.8 $ 32.5 Research and development 2.2 2.8 2.3 Marketing, selling and administrative 81.2 117.1 110.5 Total $ 105.2 $ 151.7 $ 145.3 (1) Through September 30, 2018

Selected Quarterly Data (unau_2

Selected Quarterly Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Selected Quarterly Data	2018 Fourth Third Second First Revenue $ 799.3 $ 761.1 $ 770.2 $ 736.2 Cost of sales 412.5 369.8 431.5 360.0 Operating expenses (1) 246.2 237.9 252.5 245.2 Asset Impairment, restructuring, and other special charges 46.0 12.4 68.0 2.4 Interest expense, net of capitalized interest 21.0 8.6 — — Income (loss) before income taxes (2.2 ) 78.8 (40.0 ) 77.5 Income taxes (18.6 ) 18.6 22.8 4.8 Net income (loss) 16.4 60.2 (62.8 ) 72.7 Earnings (loss) per share—basic and diluted 0.04 0.20 (0.21 ) 0.25 2017 Fourth Third Second First Revenue $ 754.3 $ 697.1 $ 732.8 $ 704.8 Cost of sales 405.0 376.2 374.0 338.6 Operating expenses (1) 258.8 256.6 257.8 258.3 Asset Impairment, restructuring, and other special charges 185.8 23.7 58.8 106.8 Interest expense, net of capitalized interest — — — — Income (loss) before income taxes (155.4 ) (9.1 ) (15.2 ) (52.9 ) Income taxes 6.1 11.6 15.0 45.4 Net income (loss) (161.5 ) (20.7 ) (30.2 ) (98.3 ) Earnings (loss) per share—basic and diluted (0.55 ) (0.07 ) (0.10 ) (0.34 ) (1) Includes research and development and marketing, selling, and administrative expenses.

Nature of Business and Organi_2

Nature of Business and Organization (Details) $ / shares in Units, $ in Millions	Sep. 24, 2018USD ($)$ / sharesshares	Dec. 31, 2018USD ($)brandcountry	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of brands in diverse portfolio (more than) | brand		125
Number of countries in which entity operates (more than) | country		90
Subsidiary, Sale of Stock [Line Items]
Amount transferred to parent		$ 3,991.3	$ 0	$ 0
IPO
Subsidiary, Sale of Stock [Line Items]
Number of shares issued | shares	72,335,000
Percentage of total outstanding shares	19.80%
Price per share (usd per share) | $ / shares	$ 24
Total net proceeds, after underwriting discounts and commissions	$ 1,700
Payments made to date		4,200
Amount transferred to parent		$ 4,000

Basis of Presentation (Details)

Basis of Presentation (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales rebates and discounts liability	$ 118.5	$ 114.8	$ 116.1
Total current liabilities	970.7	643.1
Total liabilities	3,759.2	1,160
Net parent company investment	0	8,036.9
Total equity	$ 5,197.5	7,780.3	7,017.4	$ 7,429.5
Rebates Related to Product Held in Wholesalers Pipeline | Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales rebates and discounts liability		10.5
Total current liabilities		10.5
Total liabilities		10.5
Net parent company investment		(10.5)	(10.5)
Total equity		(10.5)	(10.5)
Rebates Related to Product Held in Wholesalers Pipeline | Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Sales rebates and discounts liability		155
Total current liabilities		632.6
Total liabilities		1,149.5
Net parent company investment		8,047.4	7,484.8
Total equity		$ 7,790.8	$ 7,027.9

Impact of Separation (Details)

Impact of Separation (Details) - USD ($)	Sep. 24, 2018	Dec. 31, 2018	Feb. 18, 2019	Sep. 18, 2018	Sep. 05, 2018	Aug. 28, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Increase in net assets	$ 99,600,000	$ 99,600,000
Elanco | Lilly
Debt Instrument [Line Items]
Common shares outstanding				100			293,290,000
Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount						$ 2,000,000,000
Credit Facility | Revolving credit facility
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	750,000,000				$ 750,000,000
Credit Facility | Senior Unsecured Term Credit Facility
Debt Instrument [Line Items]
Credit facility, maximum borrowing capacity	$ 500,000,000				$ 500,000,000
Subsequent Event | Elanco | Lilly
Debt Instrument [Line Items]
Common shares outstanding			293,290,000
Ownership percentage of outstanding Common stock			80.20%

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net parent company investment		$ 0	$ (8,036.9)
Accounting Standards Update 2016-16
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net parent company investment		$ 0.3
Minimum | Accounting Standards Update 2016-02 | Subsequent Event | Scenario, Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset	$ 75
Lease liability	75
Maximum | Accounting Standards Update 2016-02 | Subsequent Event | Scenario, Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset	95
Lease liability	$ 95

Revenue - Narrative (Details)

Revenue - Narrative (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Payment terms	Payment terms differ by jurisdiction and customer, but payment terms in most of our major jurisdictions typically range from 30 to 100 days from date of shipment.
Rebate period	6 months
Geographic Concentration Risk | Contract With Customer Liability | United States
Concentration Risk [Line Items]
Concentration risk	70.00%	69.00%
Geographic Concentration Risk | Contract With Customer Liability | Next Largest Country
Concentration Risk [Line Items]
Concentration risk	8.00%
Product Return Concentration Risk | Net Revenue
Concentration Risk [Line Items]
Concentration risk	1.00%	1.00%

Revenue - Summary of Activity i

Revenue - Summary of Activity in Sales Rebates and Discounts Liability (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Change In Contract With Customer, Liability [Roll Forward]
Beginning balance	$ 116.1
Reduction of revenue	236.1	$ 221
Payments	(237.4)	(217.3)
Ending balance	$ 114.8	$ 116.1

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Total Revenue	$ 3,066.8	$ 2,889	$ 2,913.5
Companion Animal Disease Prevention
Disaggregation of Revenue [Line Items]
Total Revenue	804.6	660.2	628.4
Companion Animal Therapeutics
Disaggregation of Revenue [Line Items]
Total Revenue	283.1	260.8	255.6
Food Animal Future Protein & Health
Disaggregation of Revenue [Line Items]
Total Revenue	711.2	649.2	630.8
Food Animal Ruminants Swine
Disaggregation of Revenue [Line Items]
Total Revenue	1,174	1,175	1,309.2
Other
Disaggregation of Revenue [Line Items]
Total Revenue	$ 93.9	$ 143.8	$ 89.5

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) - USD ($) $ in Millions	Jan. 03, 2017	Apr. 22, 2016	Jan. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
BIVIVP
Business Acquisition [Line Items]
Total consideration transferred — net of cash acquired	$ 882.1		$ 882.1
Revenues					$ 216.7
Unaudited pro forma combined revenues					$ 2,890	$ 3,140
Galliprant
Business Acquisition [Line Items]
Total consideration transferred — net of cash acquired		$ 88.6
Upfront payment		45
Contingent consideration		$ 43.6
Galliprant | Development and Success-based Regulatory Milestones
Business Acquisition [Line Items]
Amount eligible to receive				$ 8
Galliprant | Potential Sales-based Milestones
Business Acquisition [Line Items]
Amount eligible to receive				60
Payment related to sales-based milestone				$ 15

Asset Impairment, Restructuri_3

Asset Impairment, Restructuring and Other Special Charges - Total Charges Related to Asset Impairment, Restructuring and Other Special Charges (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash expense:
Severance and other									$ 15.5	$ 162	$ 42.1
Integration									26.5	90.3	154.8
Facility exit costs									5.7	31.8	13.2
Total cash expense									47.7	284.1	210.1
Non-cash expense:
Asset impairment									81.9	110.6	98.3
Total non-cash expense									81.9	110.6	98.3
Gain on sale of fixed assets									(0.8)	(19.6)	0
Total expense	$ 46	$ 12.4	$ 68	$ 2.4	$ 185.8	$ 23.7	$ 58.8	$ 106.8	$ 128.8	$ 375.1	$ 308.4

Acquisitions - Summary of Amoun

Acquisitions - Summary of Amounts Recognized for Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Jan. 03, 2017	Apr. 22, 2016	Jan. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Estimated Fair Value
Goodwill (Note 11)				$ 2,958	$ 2,969.2
BIVIVP
Estimated Fair Value
Inventories	$ 108.6
Marketed products	297
Property and equipment	148.2
Other assets and liabilities — net	8.2
Total identifiable net assets	562
Goodwill (Note 11)	320.1
Total consideration transferred — net of cash acquired	$ 882.1		$ 882.1
Weighted average useful life				10 years
BIVIVP | Marketed products
Estimated Fair Value
Purchase accounting adjustment					$ 42.7
Galliprant
Estimated Fair Value
Deferred tax assets		$ 15.3
Acquired in-process research and development		31.6
Deferred tax liabilities		(15.3)
Total consideration transferred — net of cash acquired		88.6
Less: Contingent consideration		(43.6)
Total cash paid		45
Weighted average useful life				20 years
Galliprant | Marketed products
Estimated Fair Value
Marketed products		$ 57

Asset Impairment, Restructuri_4

Asset Impairment, Restructuring and Other Special Charges - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring and Related Activities [Abstract]
Intangible asset impairments	$ 22.5	$ 94.5	$ 14
Other asset impairments	$ 59.4

Asset Impairment, Restructuri_5

Asset Impairment, Restructuring and Other Special Charges - Summary of Activity in Reserves (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restructuring Reserve [Roll Forward]
Balance at beginning of period	$ 78	$ 38.1
Charges	27.2	193.8
Separation adjustment	(5.9)
Reserve adjustment	(6)	(2.5)
Cash paid	(48.9)	(151.4)
Balance at end of period	44.4	78
Exit costs
Restructuring Reserve [Roll Forward]
Balance at beginning of period	34.9	11.5
Charges	11.7	31.8
Separation adjustment	(5.9)
Reserve adjustment	(6)	1.4
Cash paid	(25.4)	(9.8)
Balance at end of period	9.3	34.9
Severance
Restructuring Reserve [Roll Forward]
Balance at beginning of period	43.1	26.6
Charges	15.5	162
Separation adjustment	0
Reserve adjustment	0	(3.9)
Cash paid	(23.5)	(141.6)
Balance at end of period	$ 35.1	$ 43.1

Inventories - Schedule of Inven

Inventories - Schedule of Inventories (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Finished products	$ 400.7	$ 452
Work in process	570.4	580
Raw materials and supplies	80.4	70.4
Total (approximates replacement cost)	1,051.5	1,102.4
Decrease to LIFO cost	(47.4)	(40.1)
Inventories	$ 1,004.1	$ 1,062.3

Inventories - Narrative (Detail

Inventories - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventories valued under the LIFO method	$ 194.8	$ 231.4
Inventory write-offs	$ 38.6

Debt - Schedule of Long-term De

Debt - Schedule of Long-term Debt (Details) - USD ($) $ in Millions	Dec. 31, 2018	Aug. 28, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (20.7)
Long-term debt	2,472.3
Less current portion of long-term debt	(29)		$ 0
Total long-term debt	2,443.3		$ 0
Credit Facility | Term credit facility
Debt Instrument [Line Items]
Long-term debt, gross	$ 492.5
Senior Notes | 3.912% Senior Notes due 2021
Debt Instrument [Line Items]
Interest rate	3.912%	3.912%
Long-term debt, gross	$ 500
Senior Notes | 4.272% Senior Notes due 2023
Debt Instrument [Line Items]
Interest rate	4.272%	4.272%
Long-term debt, gross	$ 750
Senior Notes | 4.900% Senior Notes due 2028
Debt Instrument [Line Items]
Interest rate	4.90%	4.90%
Long-term debt, gross	$ 750
Other obligations
Debt Instrument [Line Items]
Long-term debt, gross	$ 0.5

Debt - Narrative (Details)

Debt - Narrative (Details) - USD ($)	Sep. 05, 2018	Dec. 31, 2018	Sep. 24, 2018	Aug. 28, 2018
Credit Facility | Revolving credit facility
Debt Instrument [Line Items]
Credit facility term	5 years
Credit facility, maximum borrowing capacity	$ 750,000,000		$ 750,000,000
Borrowings outstanding		$ 0
Credit Facility | Term credit facility
Debt Instrument [Line Items]
Credit facility term	3 years
Credit facility, maximum borrowing capacity	$ 500,000,000		$ 500,000,000
Borrowings outstanding		$ 492,500,000
Interest rate at period end		3.77%
Quarterly principal payments percentage	1.50%
Senior Notes
Debt Instrument [Line Items]
Aggregate principal amount				$ 2,000,000,000
Senior Notes | 3.912% Senior Notes due 2021
Debt Instrument [Line Items]
Borrowings outstanding		$ 500,000,000
Aggregate principal amount				$ 500,000,000
Interest rate		3.912%		3.912%
Senior Notes | 4.272% Senior Notes due 2023
Debt Instrument [Line Items]
Borrowings outstanding		$ 750,000,000
Aggregate principal amount				$ 750,000,000
Interest rate		4.272%		4.272%
Senior Notes | 4.900% Senior Notes due 2028
Debt Instrument [Line Items]
Borrowings outstanding		$ 750,000,000
Aggregate principal amount				$ 750,000,000
Interest rate		4.90%		4.90%

Financial Instruments and Fai_3

Financial Instruments and Fair Value - Narrative (Details) SFr in Millions, $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2018CHF (SFr)	Dec. 31, 2018USD ($)	Oct. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Fair Value Disclosures [Abstract]
Cost and equity method investments		$ 15.3		$ 12.3
Net Investment Hedging | Designated as Hedging Instrument | Foreign Exchange Contract
Business Acquisition, Contingent Consideration [Line Items]
Derivative, term of contract	5 years
Notional amount | SFr	SFr 750
Expected cash and contra interest per year			$ 25
Loss to AOCI, net of tax		5.9
Net Investment Hedging | Designated as Hedging Instrument | Foreign Exchange Contract | Interest Expense
Business Acquisition, Contingent Consideration [Line Items]
Contra interest expense		5.6
Amortized Cost
Business Acquisition, Contingent Consideration [Line Items]
Long term debt		2,500
Galliprant
Business Acquisition, Contingent Consideration [Line Items]
Contingent consideration		37.6
Galliprant | Potential Sales-based Milestones
Business Acquisition, Contingent Consideration [Line Items]
Payment related to sales-based milestone		$ 15

Financial Instruments and Fai_4

Financial Instruments and Fair Value - Summary of Fair Value Information (Details) - Recurring - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Other current liabilities- contingent consideration | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	$ 0	$ 0
Other current liabilities- contingent consideration | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	0	0
Other current liabilities- contingent consideration | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	5.1	1.3
Other current liabilities- contingent consideration | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	5.1	1.3
Other current liabilities- contingent consideration | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	5.1	1.3
Other noncurrent liabilities- contingent consideration
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other noncurrent liabilities- cross currency interest rate contracts designated as net investment hedges
Other noncurrent liabilities- contingent consideration | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	0	0
Other noncurrent liabilities- cross currency interest rate contracts designated as net investment hedges	0
Other noncurrent liabilities- contingent consideration | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	0	0
Other noncurrent liabilities- cross currency interest rate contracts designated as net investment hedges	7.4
Other noncurrent liabilities- contingent consideration | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	69	45.2
Other noncurrent liabilities- cross currency interest rate contracts designated as net investment hedges	0
Other noncurrent liabilities- contingent consideration | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	69	45.2
Other noncurrent liabilities- cross currency interest rate contracts designated as net investment hedges	7.4
Other noncurrent liabilities- contingent consideration | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liabilities	69	$ 45.2
Other noncurrent liabilities- cross currency interest rate contracts designated as net investment hedges	$ 7.4

Goodwill and Intangibles - Narr

Goodwill and Intangibles - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill (Note 11)	$ 2,958,000,000	$ 2,969,200,000
Impairments with respect to the carrying value of goodwill	0	0	$ 0
Impairment charges	22,500,000	94,500,000	$ 14,000,000
Impairment of finite-lived intangible assets	9,500,000	56,500,000
Impairment of indefinite-lived intangible assets	$ 13,000,000	$ 38,000,000
Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	3 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful lives	20 years
Weighted-Average
Finite-Lived Intangible Assets [Line Items]
Remaining amortization period	14 years

Goodwill and Intangibles - Comp

Goodwill and Intangibles - Components of Intangible Assets Other Than Goodwill (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Carrying Amount, Gross	$ 3,246.6	$ 3,205.3
Accumulated Amortization	(813.2)	(629.7)
Carrying Amount, Net	2,433.4	2,575.6
Other intangibles
Carrying Amount, Gross	3,266.2	3,302.5
Accumulated Amortization	(813.2)	(629.7)
Carrying Amount, Net	2,453	2,672.8
Acquired in-process research and development
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	19.6	97.2
Marketed products
Finite-Lived Intangible Assets [Line Items]
Carrying Amount, Gross	3,193.5	3,151.2
Accumulated Amortization	(779.2)	(599.8)
Carrying Amount, Net	2,414.3	2,551.4
Other intangibles
Accumulated Amortization	(779.2)	(599.8)
Other
Finite-Lived Intangible Assets [Line Items]
Carrying Amount, Gross	53.1	54.1
Accumulated Amortization	(34)	(29.9)
Carrying Amount, Net	19.1	24.2
Other intangibles
Accumulated Amortization	$ (34)	$ (29.9)

Goodwill and Intangibles - Esti

Goodwill and Intangibles - Estimated Amortization Expense (Details) $ in Millions	Dec. 31, 2018USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2,019	$ 197.9
2,020	198.3
2,021	198
2,022	196
2,023	$ 195.8

Property and Equipment - Narrat

Property and Equipment - Narrative (Details)	12 Months Ended
	Dec. 31, 2018
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	12 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	50 years
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	25 years

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,801	$ 1,754.4
Less accumulated depreciation	(878.6)	(834.1)
Property and equipment, net	922.4	920.3
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	27.6	25.1
Buildings
Property, Plant and Equipment [Line Items]
Property and equipment, gross	567.2	557.7
Equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,025.1	994.5
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 181.1	$ 177.1

Property and Equipment - Deprec

Property and Equipment - Depreciation Expense and Rental Expense for All Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 81.3	$ 79.8	$ 75.7
Rental expense	$ 47.5	$ 47.1	$ 41.8

Property and Equipment - Future

Property and Equipment - Future Minimum Rental Commitments (Details) $ in Millions	Dec. 31, 2018USD ($)
Lease commitments
2,019	$ 25.2
2,020	20.1
2,021	13.5
2,022	10
2,023	8.3
After 2,023	$ 18.5

Stock-Based Compensation - Narr

Stock-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average remaining contractual term of the exercisable options	9 years 9 months 18 days
Exercisable options, aggregate intrinsic value (usd per share)	$ 0.08
Lilly's Stock-Based Compensation Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 26	$ 25	$ 20.4
Lilly's Stock-Based Compensation Program | PAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Fair value granted (usd per share)	$ 71.63	$ 73.54	$ 72
Number of shares issued (in shares)	39,771	69,144	20,329
Unrecognized compensation cost	$ 5.8
Weighted-average remaining requisite service period	12 months
Lilly's Stock-Based Compensation Program | SVAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Fair value granted (usd per share)	$ 49.38	$ 66.25	$ 48.68
Number of shares issued (in shares)	30,195	35,063	36,071
Unrecognized compensation cost	$ 3.5
Weighted-average remaining requisite service period	20 months
Lilly's Stock-Based Compensation Program | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Fair value granted (usd per share)	$ 70.95	$ 72.47	$ 71.46
Number of shares issued (in shares)	82,025	57,224	26,468
Unrecognized compensation cost	$ 12.5
Weighted-average remaining requisite service period	20 months
Elanco Stock Compensation Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 1.8
Related tax benefits	$ 0.4
Elanco Stock Compensation Plans | RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Fair value granted (usd per share)	$ 31.09
Number of shares issued (in shares)	18,991
Unrecognized compensation cost	$ 3.9
Weighted-average remaining requisite service period	33 months
Number of shares granted (in shares)	158,007
Elanco Stock Compensation Plans | Stock Option Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Exercise price for stock option, percent	100.00%
Expiration period	10 years

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Assumptions Used (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Lilly's Stock-Based Compensation Program | SVAs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	2.50%	2.50%	2.00%
Risk-free interest rate	2.31%	1.38%	0.92%
Volatility	22.26%	22.91%	21.68%
Vesting period	3 years
Elanco Stock Compensation Plans | Stock Option Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.70%
Risk-free interest rate	3.07%
Volatility	28.25%
Expected term (years)	6 years 6 months
Vesting period	3 years
Expiration period	10 years

Stock-Based Compensation - Sc_2

Stock-Based Compensation - Schedule of Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Shares of Common Stock Attributable to Options
Outstanding at beginning of period (in shares) | shares	0
Granted (in shares) | shares	421,297
Exercised (in shares) | shares	0
Forfeited or expired (in shares) | shares	0
Outstanding at end of period (in shares) | shares	421,297
Exercisable (in shares) | shares	58,766
Weighted-Average Exercise Price of Options
Outstanding at beginning of period (usd per share) | $ / shares	$ 0
Granted (usd per share) | $ / shares	31.61
Exercised (usd per share) | $ / shares	0
Forfeited or expired (usd per share) | $ / shares	0
Outstanding at end of period (usd per share) | $ / shares	31.61
Exercisable (usd per share) | $ / shares	$ 31.61

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	Sep. 24, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Re-measurement of deferred taxes included as a component of income tax benefit		$ 0	$ 33,100,000	$ 0
Operating Loss Carryforwards [Line Items]
Tax credit carryovers		6,500,000
Net operating losses and other carryovers		21,700,000	144,900,000
Separation entries related to the removal of the net operating losses	$ 133,700,000
Taxes accrued with respect to unremitted earnings of foreign subsidiaries		0
Unremitted earnings of foreign subsidiaries		464,500,000
Unrecognized tax benefits that, if recognized, would affect effective tax rate		12,800,000	29,600,000
Unrecognized tax benefits that, if recognized, would not affect effective tax rate		1,900,000
Accruals for payment of interest and penalties		13,300,000	$ 15,700,000
Foreign
Operating Loss Carryforwards [Line Items]
Tax credit carryovers		4,100,000
State
Operating Loss Carryforwards [Line Items]
Tax credit carryovers		2,400,000
Net operating losses and other carryovers		4,900,000
International and Federal
Operating Loss Carryforwards [Line Items]
Net operating losses and other carryovers		156,200,000
Net operating loss carryforwards that will never expire		1,600,000
International and Federal | 2023
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards that expire		84,600,000
International and Federal | 2024 To 2025
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards that expire		$ 65,000,000

Income Taxes - Composition of I

Income Taxes - Composition of Income (Loss) Before Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal									$ 12.2	$ (133.2)	$ (12.5)
Foreign									101.9	(99.4)	(9.9)
Income (loss) before income taxes	$ (2.2)	$ 78.8	$ (40)	$ 77.5	$ (155.4)	$ (9.1)	$ (15.2)	$ (52.9)	$ 114.1	$ (232.6)	$ (22.4)

Income Taxes - Composition of_2

Income Taxes - Composition of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal									$ 45.1	$ 0	$ 0
Foreign									45.5	91.6	31.1
State									(2.3)	(0.1)	0.3
Total current tax expense									88.3	91.5	31.4
Deferred:
Federal									(56.8)	42.6	18.4
Foreign									(5.6)	(16.6)	(26.8)
State									1.7	(6.3)	2.5
2017 Tax Act									0	(33.1)	0
Total deferred tax benefit									(60.7)	(13.4)	(5.9)
Income taxes	$ (18.6)	$ 18.6	$ 22.8	$ 4.8	$ 6.1	$ 11.6	$ 15	$ 45.4	$ 27.6	$ 78.1	$ 25.5

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Compensation and benefits	$ 32.2	$ 34.8
Accruals and reserves	47.8	12
Tax credit carryovers	1.9	19.2
Tax loss carryovers	21.7	144.9
Other	23.5	26.6
Total gross deferred tax assets	127.1	237.5
Valuation allowances	(21.4)	(127.7)
Total deferred tax assets	105.7	109.8
Deferred tax liabilities:
Intangibles	(130.8)	(165.2)
Property and equipment	(50.8)	(43.1)
Other	(2.7)	(7.4)
Total deferred tax liabilities	(184.3)	(215.7)
Deferred tax liabilities - net	$ (78.6)	$ (105.9)

Income Taxes - Movements in the

Income Taxes - Movements in the Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2016
Valuation Allowance, Deferred Tax Asset
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ (17.3)
Increase	(5.8)	$ (97.4)
Release	1.7	8.8
Ending balance	(21.4)	(39.1)
Previously Reported | Valuation Allowance, Deferred Tax Asset
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	(127.7)
Ending balance		(39.1)
Adjustment related to Separation
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ 110.4
Ending balance		$ 0

Income Taxes - Cash Payments of

Income Taxes - Cash Payments of Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Cash payments of income taxes	$ 26.9	$ 35.7	$ 53.6

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax at the U.S. federal statutory tax rate									$ 24	$ (81.4)	$ (7.8)
Add (deduct):
International operations and change in foreign tax rates									11.5	55.6	8.4
State taxes									4.4	5.4	2.8
Income tax credits									(17.3)	(1.8)	(1.7)
Foreign inclusion items									9	4.2	2.4
IPO and separation costs									2.3	0	0
Other permanent adjustments									0.9	1.6	0.2
Change in uncertain tax positions									(1.7)	6.2	5.2
Change in valuation allowance									(1.7)	122.2	18.1
2017 Tax Act									0	(33.1)	0
Other									(3.8)	(0.8)	(2.1)
Income taxes	$ (18.6)	$ 18.6	$ 22.8	$ 4.8	$ 6.1	$ 11.6	$ 15	$ 45.4	$ 27.6	$ 78.1	$ 25.5

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 29.6	$ 25.7
Additions based on tax positions related to the current year	2.2	7.9	$ 7.4
Additions for tax positions of prior years	4	0	0
Settlements	(3)	(4)	(7.1)
Changes related to the impact of foreign currency translation	(0.5)	0	(0.1)
Ending balance	14.7	29.6	25.7
Adjustment related to Separation
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	(17.6)	0	0
Ending balance		(17.6)	0
Valuation Allowance, Deferred Tax Asset
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	12	25.7	25.5
Ending balance		12	25.7
Valuation Allowance, Deferred Tax Asset | Previously Reported
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 29.6	25.7	25.5
Ending balance		$ 29.6	$ 25.7

Income Taxes - Income Tax Expen

Income Taxes - Income Tax Expense (Benefit) Related to Interest and Penalties (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ (2.5)	$ 2.5	$ 5.5

Contingencies (Details)

Contingencies (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Liabilities related to litigation	$ 0	$ 0

Geographic Information - Narrat

Geographic Information - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016
Segment Reporting [Abstract]
Number of operating segments | segment	1
Concentration Risk [Line Items]
Accounts receivable	$ 651.8	$ 567.4
Product Sales
Concentration Risk [Line Items]
Accounts receivable	$ 96.4	$ 88
Customer Concentration Risk | Revenue | Single Customer
Concentration Risk [Line Items]
Concentration risk	11.90%	12.90%	11.70%

Geographic Information - Revenu

Geographic Information - Revenue and Long-lived Assets by Selected Geographic Area Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 799.3	$ 761.1	$ 770.2	$ 736.2	$ 754.3	$ 697.1	$ 732.8	$ 704.8	$ 3,066.8	$ 2,889	$ 2,913.5
Long-lived assets	985.9				999.3				985.9	999.3	827.4
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									1,483.2	1,373	1,361.6
Long-lived assets	602.6				604.7				602.6	604.7	463.8
International
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue									1,583.6	1,516	1,551.9
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	187.5				204.4				187.5	204.4	190.6
Other foreign countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 195.8				$ 190.2				$ 195.8	$ 190.2	$ 173

Retirement Benefits - Narrative

Retirement Benefits - Narrative (Details)	12 Months Ended
	Dec. 31, 2018USD ($)plan	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Retirement Benefits [Abstract]
Multiemployer plans expense	$ 4,000,000	$ 73,700,000	$ 11,300,000
Multiemployer plans, curtailment loss and special termination benefits		67,000,000
Multiemployer plan contributions	0
Defined Benefit Plan Disclosure [Line Items]
Accrued retirement benefits (Note 17)	109,100,000	139,000,000
Expenses related to employees under Defined Contribution Plans	20,900,000	22,100,000	$ 19,600,000
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Total accumulated benefit obligation	199,900,000	230,300,000
Contributions expected in 2019	0
Accrued retirement benefits (Note 17)	$ 105,200,000	129,200,000
Pension Plans | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Designated percentage invested	24.00%
Pension Plans | Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Designated percentage invested	48.00%
Pension Plans | Real Estate Switzerland
Defined Benefit Plan Disclosure [Line Items]
Designated percentage invested	11.00%
Pension Plans | Other Alternative Investments
Defined Benefit Plan Disclosure [Line Items]
Designated percentage invested	17.00%
Pension Plans | Switzerland
Defined Benefit Plan Disclosure [Line Items]
Percentage of benefit obligation in Switzerland pension plans	84.00%
Percentage of plan assets in Switzerland pension plans	87.00%
Retiree Health Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Number of plans | plan	2
Accrued retirement benefits (Note 17)	$ 3,900,000	$ 9,800,000

Retirement Benefits - Change in

Retirement Benefits - Change in Benefit Obligation, Change in Plan Assets, and Funded Status (Details) - Pension Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in benefit obligation:
Benefit obligation at beginning of year	$ 258.6	$ 225
Service cost	11.3	10.5	$ 9.3
Interest cost	2.5	1.8	1.8
Actuarial (gain) loss	(44.7)	24.4
Benefits paid	(2.7)	(18.5)
Foreign currency exchange rate changes and other adjustments	9.8	15.4
Benefit obligation at end of year	234.8	258.6	225
Change in plan assets:
Fair value of plan assets at beginning of year	131.5	123.7
Actual return on plan assets	(10.2)	13.3
Employer contribution	5.7	3.9
Benefits paid	(2.7)	(18.5)
Foreign currency exchange rate changes and other adjustments	7.3	9.1
Fair value of plan assets at end of year	131.6	131.5	$ 123.7
Funded status	(103.2)	(127.1)
Unrecognized net actuarial loss	0.5	29.1
Unrecognized prior service cost	0.8	0.7
Net amount recognized	$ (101.9)	$ (97.3)

Retirement Benefits - Amounts R

Retirement Benefits - Amounts Recognized in Combined Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Amounts recognized in the combined balance sheet consisted of:
Accrued retirement benefits	$ (109.1)	$ (139)
Pension Plans
Amounts recognized in the combined balance sheet consisted of:
Noncurrent assets	2.3	2.4
Other current liabilities	(0.3)	(0.3)
Accrued retirement benefits	(105.2)	(129.2)
Accumulated other comprehensive loss before income taxes	1.3	29.8
Net amount recognized	$ (101.9)	$ (97.3)

Retirement Benefits - Component

Retirement Benefits - Components of Accumulated Other Comprehensive Loss to be Recognized over Next Fiscal Year (Details) - Pension Plans $ in Millions	Dec. 31, 2018USD ($)
Defined Benefit Plan Disclosure [Line Items]
Unrecognized net actuarial loss	$ 0.5
Unrecognized prior service cost	0.8
Total	$ 1.3

Retirement Benefits - Weighted-

Retirement Benefits - Weighted-Average Assumptions Related to Pension Plans (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase for benefit obligation	2.20%	2.10%	3.10%
Rate of compensation increase for net benefit costs	2.10%	3.10%	3.00%
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligation	1.50%	1.10%	1.00%
Discount rate for net benefit costs	1.10%	1.00%	1.00%
Expected return on plan assets for net benefit costs	4.00%	4.40%	4.90%

Retirement Benefits - Schedule

Retirement Benefits - Schedule of Expected Benefit Payments (Details) - Pension Plans $ in Millions	Dec. 31, 2018USD ($)
Benefit payments
2,019	$ 5.8
2,020	6.4
2,021	7.1
2,022	6.1
2,023	6.3
2024-2028	$ 35.9

Retirement Benefits - Projected

Retirement Benefits - Projected Benefit Obligations in Excess of Plan Assets (Details) - Pension Plans - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 229.2	$ 251.6
Fair value of plan assets	$ 124.1	$ 121.8

Retirement Benefits - Accumulat

Retirement Benefits - Accumulated Benefit Obligations in Excess of Plan Assets (Details) - Pension Plans - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 194.3	$ 223.1
Fair value of plan assets	$ 124.1	$ 121.8

Retirement Benefits - Net Pensi

Retirement Benefits - Net Pension Expense (Details) - Pension Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 11.3	$ 10.5	$ 9.3
Interest cost	2.5	1.8	1.8
Expected return on plan assets	(6.2)	(2.4)	(3.4)
Amortization of prior service cost	0.2	0.1	0.1
Amortization of net actuarial loss	1.9	1.4	1
Other	0.5	0	0
Net pension expense	$ 10.2	$ 11.4	$ 8.8

Retirement Benefits - Amounts_2

Retirement Benefits - Amounts Recognized in Other Comprehensive Loss (Details) - Pension Plans - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Pension Plans
Actuarial gain (loss) arising during period	$ 28.3	$ (17)	$ (6.1)
Amortization of prior service cost included in net loss	0.2	0.1	0.1
Amortization of net actuarial loss included in net loss	1.9	1.4	1
Foreign currency exchange rate changes and other	(1.9)	3.5	3
Total other comprehensive income (loss) during period	$ 28.5	$ (12)	$ (2)

Retirement Benefits - Fair Valu

Retirement Benefits - Fair Value of Pension Plan Assets (Details) - Pension Plans - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 131.6	$ 131.5	$ 123.7
Public equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.2	0.8
Developed markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29.9	29.9
Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.4	7.2
Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.6	6.8
Equity-like funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49	52.7
Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20.1	20.2
Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17.4	13.9
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	9.9	9.5
Quoted Prices in Active Markets for Identical Assets (Level 1) | Public equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	0.6
Quoted Prices in Active Markets for Identical Assets (Level 1) | Developed markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7.8	8.2
Quoted Prices in Active Markets for Identical Assets (Level 1) | Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.7	0.6
Quoted Prices in Active Markets for Identical Assets (Level 1) | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity-like funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.1	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.3	0.1
Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.8	0.5
Significant Other Observable Inputs (Level 2) | Public equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Other Observable Inputs (Level 2) | Developed markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.1	0.1
Significant Other Observable Inputs (Level 2) | Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0.4	0.3
Significant Other Observable Inputs (Level 2) | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Other Observable Inputs (Level 2) | Equity-like funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Other Observable Inputs (Level 2) | Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Other Observable Inputs (Level 2) | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2.3	0.1
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Unobservable Inputs (Level 3) | Public equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Unobservable Inputs (Level 3) | Developed markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Unobservable Inputs (Level 3) | Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Unobservable Inputs (Level 3) | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Unobservable Inputs (Level 3) | Equity-like funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Unobservable Inputs (Level 3) | Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Significant Unobservable Inputs (Level 3) | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Investments Valued at Net Asset Value
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	118.9	121.5
Investments Valued at Net Asset Value | Public equity securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1.2	0.2
Investments Valued at Net Asset Value | Developed markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	22	21.6
Investments Valued at Net Asset Value | Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5.3	6.3
Investments Valued at Net Asset Value | Hedge funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.6	6.8
Investments Valued at Net Asset Value | Equity-like funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49	52.7
Investments Valued at Net Asset Value | Real estate
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20	20.2
Investments Valued at Net Asset Value | Other
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 14.8	$ 13.7

Earnings Per Share (Details)

Earnings Per Share (Details)	Sep. 24, 2018shares	Sep. 19, 2018	Dec. 31, 2016shares	Sep. 18, 2018shares	Dec. 31, 2017shares
Subsidiary, Sale of Stock [Line Items]
Stock split ratio		2,932,900
Number of shares outstanding			293,290,000
IPO
Subsidiary, Sale of Stock [Line Items]
Number of shares issued	72,335,000
Elanco | Lilly
Subsidiary, Sale of Stock [Line Items]
Common shares outstanding				100	293,290,000

Related Party Agreements and _3

Related Party Agreements and Transactions - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)renewal_term	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Related Party Transaction [Line Items]
Payable to Lilly	$ 268.7	$ 0
Net transfers (to)/from Lilly	(226.3)	873.3	$ (129.2)
Acquisition amount	0	882.1	45
Boehringer Ingelheim Vetmedica, Inc.
Related Party Transaction [Line Items]
Acquisition amount		882.1
Lilly
Related Party Transaction [Line Items]
Payable to Lilly	66
Stock-based compensation	26	25	20.4
Costs/(benefits) of defined benefit pension plan	(6.3)	73.7	11.3
Lilly | MSA
Related Party Transaction [Line Items]
Total net assets	95.6
Restricted cash retained	$ 202.7
Lilly | TSA
Related Party Transaction [Line Items]
Mark-up rate	7.00%
Revenue from related parties	$ 28
Lilly | Intellectual Property and Technology License Agreement
Related Party Transaction [Line Items]
Initial term	2 years
Number of renewal terms | renewal_term	3
Extension term	1 year
Lilly | Toll Manufacturing Arrangement
Related Party Transaction [Line Items]
Revenue from related parties	$ 7
Lilly | Manufacturing Support
Related Party Transaction [Line Items]
Revenue from related parties	3.7	6.2	5.5
Director | Commercial Operations
Related Party Transaction [Line Items]
Revenue from related parties	23.5	24.8	14.3
Accounts receivable	2.5	2
Purchases of goods and services	3.9	5.9	$ 7.1
Accounts payable	0.7	$ 0.4
IPO
Related Party Transaction [Line Items]
Amount transferred to parent	$ 4,200

Related Party Agreements and _4

Related Party Agreements and Transactions - Amounts Reflected in Consolidated and Combined Financial Statement of Operations and Allocations of Services (Details) - Lilly - Transitional Services Agreement - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Allocation of services	$ 105.2	$ 151.7	$ 145.3
Cost of sales
Related Party Transaction [Line Items]
Allocation of services	21.8	31.8	32.5
Research and development
Related Party Transaction [Line Items]
Allocation of services	2.2	2.8	2.3
Marketing, selling and administrative
Related Party Transaction [Line Items]
Allocation of services	$ 81.2	$ 117.1	$ 110.5

Selected Quarterly Data (unau_3

Selected Quarterly Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 799.3	$ 761.1	$ 770.2	$ 736.2	$ 754.3	$ 697.1	$ 732.8	$ 704.8	$ 3,066.8	$ 2,889	$ 2,913.5
Cost of sales	412.5	369.8	431.5	360	405	376.2	374	338.6	1,573.8	1,493.9	1,409
Operating expenses	246.2	237.9	252.5	245.2	258.8	256.6	257.8	258.3
Asset Impairment, restructuring, and other special charges	46	12.4	68	2.4	185.8	23.7	58.8	106.8	128.8	375.1	308.4
Interest expense, net of capitalized interest	21	8.6	0	0	0	0	0	0	29.6	0	0
Income (loss) before income taxes	(2.2)	78.8	(40)	77.5	(155.4)	(9.1)	(15.2)	(52.9)	114.1	(232.6)	(22.4)
Income taxes	(18.6)	18.6	22.8	4.8	6.1	11.6	15	45.4	27.6	78.1	25.5
Net income (loss)	$ 16.4	$ 60.2	$ (62.8)	$ 72.7	$ (161.5)	$ (20.7)	$ (30.2)	$ (98.3)	$ 86.5	$ (310.7)	$ (47.9)
Earnings (loss) per share—basic and diluted (usd per share)	$ 0.04	$ 0.20	$ (0.21)	$ 0.25	$ (0.55)	$ (0.07)	$ (0.10)	$ (0.34)	$ 0.28	$ (1.06)	$ (0.16)

Uncategorized Items - elan-2018

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (300,000)
Net Parent Company Investment [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (300,000)