DexCom (DXCM) 10-Q 29 Jul 21 2021 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2021	Jul. 22, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2021
Document Transition Report	false
Entity File Number	000-51222
Entity Registrant Name	DEXCOM, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0857544
Entity Address, Address Line One	6340 Sequence Drive
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	200-0200
Title of 12(b) Security	Common Stock, $0.001 Par Value Per Share
Trading Symbol	DXCM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		96,748,901
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001093557
Current Fiscal Year End Date	--12-31

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 1,158.8	$ 817.6
Short-term marketable securities	1,426.1	1,890.1
Accounts receivable, net	483.5	428.5
Inventory	319.3	234.7
Prepaid and other current assets	86.5	53.9
Total current assets	3,474.2	3,424.8
Property and equipment, net	676	515.3
Operating lease right-of-use assets	94.8	93.3
Goodwill	19.1	19.3
Deferred tax assets	216.4	216.4
Other assets	23.3	21.4
Total assets	4,503.8	4,290.5
Current liabilities:
Accounts payable and accrued liabilities	482	481.1
Accrued payroll and related expenses	98.1	114.3
Short-term operating lease liabilities	18.8	16.5
Deferred revenue	1.8	2.2
Total current liabilities	600.7	614.1
Long-term senior convertible notes	1,710.7	1,667.2
Long-term operating lease liabilities	107.1	101.8
Other long-term liabilities	87.7	80.9
Total liabilities	2,506.2	2,464
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value, 5.0 million shares authorized; no shares issued and outstanding at June 30, 2021 and December 31, 2020	0	0
Common stock, $0.001 par value, 200.0 million shares authorized; 97.5 million and 96.7 million shares issued and outstanding, respectively, at June 30, 2021; and 96.9 million and 96.1 million shares issued and outstanding, respectively, at December 31, 2020	0.1	0.1
Additional paid-in capital	2,193.6	2,125.3
Accumulated other comprehensive income	2.8	3.2
Accumulated deficit	(98.9)	(202.1)
Treasury stock, at cost; 0.8 million shares at June 30, 2021 and December 31, 2020	(100)	(100)
Total stockholders’ equity	1,997.6	1,826.5
Total liabilities and stockholders’ equity	$ 4,503.8	$ 4,290.5

Consolidated Balance Sheets (_2

Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Preferred stock, par value (USD per share)	$ 0.001	$ 0.001
Preferred stock authorized (in shares)	5,000,000	5,000,000
Preferred stock issued (in shares)	0	0
Preferred stock outstanding (in shares)	0	0
Common stock, par value (USD per share)	$ 0.001	$ 0.001
Common stock authorized (in shares)	200,000,000	200,000,000
Common stock issued (in shares)	97,500,000	96,900,000
Common stock outstanding (in shares)	96,700,000	96,100,000
Treasury stock (in shares)	800,000	800,000

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Income Statement [Abstract]
Revenues	$ 595.1	$ 451.8	$ 1,100.1	$ 856.9
Cost of sales	178	167.7	339.1	316.3
Gross profit	417.1	284.1	761	540.6
Operating expenses:
Research and development	129.1	79.9	238.5	153
Selling, general and administrative	187	136.4	375.6	286.2
Total operating expenses	316.1	216.3	614.1	439.2
Operating income	101	67.8	146.9	101.4
Interest expense	(25.2)	(20.3)	(50)	(35.7)
Loss on extinguishment of debt	0	(5.4)	0	(5.4)
Interest and other income, net	0.9	4.1	1	8.3
Income before income taxes	76.7	46.2	97.9	68.6
Income tax expense (benefit)	13.8	(0.1)	(5.3)	2.4
Net income	$ 62.9	$ 46.3	$ 103.2	$ 66.2
Basic net income per share (USD per share)	$ 0.65	$ 0.49	$ 1.07	$ 0.71
Shares used to compute basic net income per share (in shares)	96.7	93.8	96.5	92.8
Diluted net income per share (USD per share)	$ 0.63	$ 0.48	$ 1.04	$ 0.69
Shares used to compute diluted net income per share (in shares)	99.6	97	99.5	95.6

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 62.9	$ 46.3	$ 103.2	$ 66.2
Other comprehensive income (loss), net of tax:
Translation adjustments and other	0.2	0.5	(0.1)	(0.2)
Unrealized gain (loss) on marketable debt securities	(0.3)	(0.7)	(0.3)	1.4
Total other comprehensive income (loss), net of tax	(0.1)	(0.2)	(0.4)	1.2
Comprehensive income	$ 62.8	$ 46.1	$ 102.8	$ 67.4

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Treasury Stock
Balance at beginning of period (in shares) at Dec. 31, 2019		91.6
Balance at beginning of period at Dec. 31, 2019	$ 882.6	$ 0.1	$ 1,675.9	$ 2.3	$ (695.7)	$ (100)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under equity incentive plans (in shares)		0.8
Issuance of common stock under equity incentive plans	0.3		0.3
Issuance of common stock for Employee Stock Purchase Plan	6.4		6.4
Equity component of 2025 Notes issuance, net of issuance costs	289.4		289.4
Repurchase and conversions of 2022 Notes (in shares)		3
Repurchase and conversions of 2022 Notes	53.2		53.2
Share-based compensation expense	54.6		54.6
Net income	66.2				66.2
Other comprehensive loss, net of tax	1.2			1.2
Balance at end of period (in shares) at Jun. 30, 2020		95.4
Balance at end of period at Jun. 30, 2020	1,353.9	$ 0.1	2,079.8	3.5	(629.5)	(100)
Balance at beginning of period (in shares) at Mar. 31, 2020		92.3
Balance at beginning of period at Mar. 31, 2020	934.5	$ 0.1	1,706.5	3.7	(675.8)	(100)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under equity incentive plans (in shares)		0.1
Issuance of common stock under equity incentive plans	0
Issuance of common stock for Employee Stock Purchase Plan	0
Equity component of 2025 Notes issuance, net of issuance costs	289.4		289.4
Repurchase and conversions of 2022 Notes (in shares)		3
Repurchase and conversions of 2022 Notes	53.2		53.2
Share-based compensation expense	30.7		30.7
Net income	46.3				46.3
Other comprehensive loss, net of tax	(0.2)			(0.2)
Balance at end of period (in shares) at Jun. 30, 2020		95.4
Balance at end of period at Jun. 30, 2020	1,353.9	$ 0.1	2,079.8	3.5	(629.5)	(100)
Balance at beginning of period (in shares) at Dec. 31, 2020		96.1
Balance at beginning of period at Dec. 31, 2020	1,826.5	$ 0.1	2,125.3	3.2	(202.1)	(100)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under equity incentive plans (in shares)		0.6
Issuance of common stock for Employee Stock Purchase Plan	8.7		8.7
Share-based compensation expense	59.6		59.6
Net income	103.2				103.2
Other comprehensive loss, net of tax	(0.4)			(0.4)
Balance at end of period (in shares) at Jun. 30, 2021		96.7
Balance at end of period at Jun. 30, 2021	1,997.6	$ 0.1	2,193.6	2.8	(98.9)	(100)
Balance at beginning of period (in shares) at Mar. 31, 2021		96.7
Balance at beginning of period at Mar. 31, 2021	1,903.2	$ 0.1	2,162	2.9	(161.8)	(100)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under equity incentive plans	0
Issuance of common stock for Employee Stock Purchase Plan	0
Share-based compensation expense	31.6		31.6
Net income	62.9				62.9
Other comprehensive loss, net of tax	(0.1)			(0.1)
Balance at end of period (in shares) at Jun. 30, 2021		96.7
Balance at end of period at Jun. 30, 2021	$ 1,997.6	$ 0.1	$ 2,193.6	$ 2.8	$ (98.9)	$ (100)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating activities
Net income	$ 103.2	$ 66.2
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	44.4	28.3
Share-based compensation	59.6	54.6
Loss on extinguishment of debt	0	5.4
Non-cash interest expense	44.7	30.3
Deferred income taxes	0.1	0
Other non-cash income and expenses	16	3.5
Changes in operating assets and liabilities:
Accounts receivable, net	(54.9)	(10.4)
Inventory	(84.5)	(45.5)
Prepaid and other assets	(27.1)	(26.6)
Operating lease right-of-use assets and liabilities, net	1.1	(1.2)
Accounts payable and accrued liabilities	0	56.8
Accrued payroll and related expenses	(16.2)	(20.8)
Deferred revenue and other liabilities	3	15.4
Net cash provided by operating activities	89.4	156
Investing activities
Purchases of marketable securities	(1,171.9)	(1,740)
Proceeds from sale and maturity of marketable securities	1,628.3	849.5
Purchases of property and equipment	(200.9)	(91.4)
Other investing activities	(4.5)	(2.8)
Net cash provided by (used in) investing activities	251	(984.7)
Financing activities
Proceeds from issuance of convertible notes, net of issuance costs	0	1,188.8
Repurchase of convertible notes	0	(282.6)
Net proceeds from issuance of common stock	8.7	6.7
Other financing activities	(8.3)	(0.4)
Net cash provided by financing activities	0.4	912.5
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.1	(0.2)
Increase in cash, cash equivalents and restricted cash	340.9	83.6
Cash, cash equivalents and restricted cash, beginning of period	818.2	446.4
Cash, cash equivalents and restricted cash, end of period	1,159.1	530
Reconciliation of cash, cash equivalents and restricted cash, end of period:
Cash and cash equivalents	1,158.8	530
Restricted cash	0.3	0
Total cash, cash equivalents and restricted cash	1,159.1	530
Supplemental disclosure of non-cash investing and financing transactions:
Common stock issued for repurchase and conversions of senior convertible notes	0	1,190
Acquisition of property and equipment included in accounts payable and accrued liabilities	43.2	17
Right-of-use assets obtained in exchange for operating lease liabilities	10.4	5.3
Right-of-use assets obtained in exchange for finance lease liabilities	$ 4.6	$ 0

Organization and Significant Ac

Organization and Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Significant Accounting Policies	1. Organization and Significant Accounting Policies Organization and Business DexCom, Inc. is a medical device company that develops and markets continuous glucose monitoring, or CGM, systems for the management of diabetes by patients, caregivers, and clinicians around the world. Unless the context requires otherwise, the terms “we,” “us,” “our,” the “company,” or “Dexcom” refer to DexCom, Inc. and its subsidiaries. Basis of Presentation and Principles of Consolidation We have prepared the accompanying unaudited consolidated financial statements in accordance with U.S. generally accepted accounting principles, or GAAP, for interim financial information and with the instructions to Form 10-Q and Article 10 of Securities and Exchange Commission, or SEC, Regulation S-X. Accordingly, they do not include all of the information and disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation, have been included. Operating results for the three and six months ended June 30, 2021 are not necessarily indicative of the results that may be expected for the year ending December 31, 2021. We expect that revenues we generate from the sales of our products will fluctuate from quarter to quarter. We experience seasonality that is typical in our industry, with lower sales in the first quarter of each year compared to the fourth quarter of the previous year. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes thereto for the year ended December 31, 2020 included in the Annual Report on Form 10-K that we filed with the SEC on February 11, 2021. These consolidated financial statements include the accounts of DexCom, Inc. and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We determine the functional currencies of our international subsidiaries by reviewing the environment where each subsidiary primarily generates and expends cash. For international subsidiaries whose functional currencies are the local currencies, we translate the financial statements into U.S. dollars using period-end exchange rates for assets and liabilities and average exchange rates for each period for revenue, costs and expenses. We include translation-related adjustments in comprehensive income and in accumulated other comprehensive income in the equity section of our consolidated balance sheets. We record gains and losses resulting from transactions with customers and vendors that are denominated in currencies other than the functional currency and from certain intercompany transactions in interest and other income, net in our consolidated statements of operations. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires us to make certain estimates and assumptions that affect the amounts reported in our consolidated financial statements and the disclosures made in the accompanying notes. Areas requiring significant estimates include rebates, transaction price, the collectibility of accounts receivable, excess or obsolete inventories and the valuation of inventory, accruals for litigation contingencies, and the amount of our worldwide tax provision and the realizability of deferred tax assets. Despite our intention to establish accurate estimates and use reasonable assumptions, actual results may differ from our estimates. Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are generally recorded at the invoiced amount for distributors and at net realizable value for direct customers, which is determined using estimates of claim denials and historical reimbursement experience without regard to aging category. Accounts receivable are not interest bearing. We evaluate the creditworthiness of significant customers based on historical trends, the financial condition of our customers, and external market factors. We generally do not require collateral from our customers. We maintain an allowance for doubtful accounts for potential credit losses. Uncollectible accounts are written off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a customer account is uncollectible. Generally, receivable balances greater than one year past due are deemed uncollectible. Concentration of Credit Risk Financial instruments which potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents, short-term marketable securities, and accounts receivable. We limit our exposure to credit risk by placing our cash and investments with a few major financial institutions. We have also established guidelines regarding diversification of our investments and their maturities that are designed to maintain principal and maximize liquidity. We review these guidelines periodically and modify them to take advantage of trends in yields and interest rates and changes in our operations and financial position. Revenue Recognition We generate our revenue from the sale of disposable sensors and our reusable transmitter and receiver, collectively referred to as Reusable Hardware. We also refer to Reusable Hardware in this section as Components. We generally recognize revenue when control is transferred to our customers in an amount that reflects the net consideration to which we expect to be entitled. In determining how revenue should be recognized, a five-step process is used, which includes identifying performance obligations in the contract, determining whether the performance obligations are separate, allocating the transaction price to each separate performance obligation, estimating the amount of variable consideration to include in the transaction price and determining the timing of revenue recognition for separate performance obligations. Contracts and Performance Obligations We consider customer purchase orders, which in most cases are governed by agreements with distributors or third-party payors, to be contracts with a customer. For each contract, we consider the obligation to transfer Components to the customer, each of which are distinct, to be separate performance obligations. We also provide free-of-charge software, mobile applications and updates for our Dexcom Share ® remote monitoring system. The standalone selling prices of Dexcom Share ® are estimated based on an expected cost plus a margin approach. Transaction Price Transaction price for the Components reflects the net consideration to which we expect to be entitled. Transaction price is typically based on the contracted rates less an estimate of claim denials and historical reimbursement experience by payor, which include current and future expectations regarding reimbursement rates and payor mix. Variable Consideration We include an estimate of variable consideration in the calculation of the transaction price at the time of sale, when control of the Components transfers to the customer. Variable consideration includes, but is not limited to: rebates, chargebacks, consideration payable to customers such as specialty distributor and wholesaler fees, product returns provision, prompt payment discounts, and various other promotional or incentive arrangements. We classify our provisions related to variable consideration as a reduction of accounts receivable when we are not required to make a payment or as a liability when we are required to make a payment. Rebates We are subject to rebates on pricing programs with managed care organizations, such as pharmacy benefit managers, governmental and third-party commercial payors, primarily in the U.S. We estimate provisions for rebates based on contractual arrangements, estimates of products sold subject to rebate, known events or trends and channel inventory data. Chargebacks We participate in chargeback programs, primarily with government entities in the U.S., under which pricing on products below negotiated list prices is provided to participating entities and equal to the difference between their acquisition cost and the lower negotiated price. We estimate provisions for chargebacks primarily based on historical experience on a product and program basis, current contract prices under the chargeback programs and channel inventory data. Consideration Payable to the Customer We pay administrative and service fees to certain of our distributors based on a fixed percentage of the product price. These fees are not in exchange for a distinct good or service and therefore are recognized as a reduction of the transaction price. We accrue for these fees based on actual net sales and contractual fee rates negotiated with the customer. Product Returns In accordance with the terms of their distribution agreements, most distributors do not have rights of return. The distributors typically have a limited time frame to notify us of any missing, damaged, defective or non-conforming products. We generally provide a “30-day money back guarantee” program whereby first-time end-user customers may return Reusable Hardware. We estimate our product returns provision principally based on historical experience by applying a historical return rate to the amounts of revenue estimated to be subject to returns. Additionally, we consider other specific factors such as estimated shelf life of inventory in the distribution channel and changes to customer terms. Prompt Payment Discounts We provide customers with prompt payment discounts which may result in adjustments to the price that is invoiced for the product transferred, in the case that payments are made within a defined period. We estimate prompt payment discount accruals based on actual net sales and contractual discount rates. Various Other Promotional or Incentive Arrangements Other promotional or incentive arrangements are periodically offered to customers, including but not limited to co-payment assistance we provide to patients with commercial insurance, promotional programs related to the launch of products or other targeted promotions. We record a provision for the incentive earned based on the number of estimated claims and our estimate of the cost per claim related to product sales that we have recognized as revenue. Revenue Recognition The timing of revenue recognition is based on the satisfaction of performance obligations. Substantially all of the performance obligations associated with our Components are satisfied at a point in time, which typically occurs at shipment of our products. Terms of direct and distributor orders are generally Freight on Board (FOB) shipping point for U.S. orders or Free Carrier (FCA) shipping point for international orders. For certain sales transactions, control transfers at delivery of the product to the customer. In cases where our free-of-charge software, mobile applications and updates are deemed to be separate performance obligations, revenue is recognized over time on a ratable basis over the estimated life of the related Reusable Hardware component. Our sales of Components include an assurance-type warranty. Contract Balances Contract balances represent amounts presented in our consolidated balance sheets when either we have transferred goods or services to the customer or the customer has paid consideration to us under the contract. These contract balances include accounts receivable and deferred revenue. Payment terms vary by contract type and type of customer and generally range from 30 to 90 days. Accounts receivable as of June 30, 2021 included unbilled accounts receivable of $11.1 million. We expect to invoice and collect all unbilled accounts receivable within 12 months. We record deferred revenue when we have entered into a contract with a customer and cash payments are received or due prior to transfer of control or satisfaction of the related performance obligation. Our performance obligations are generally satisfied within 12 months of the initial contract date. The deferred revenue balance related to performance obligations that will be satisfied after 12 months was $11.6 million as of June 30, 2021 and $8.2 million as of December 31, 2020. These balances are included in other long-term liabilities in our consolidated balance sheets. Revenue recognized in the period from performance obligations satisfied in previous periods was not material for the periods presented. Deferred Cost of Sales Deferred cost of sales are associated with transactions for which revenue recognition criteria are not met but product has shipped and released from inventory. Deferred cost of sales are included in prepaid and other current assets in our consolidated balance sheets. Incentive Compensation Costs We generally expense incentive compensation associated with our internal sales force when incurred because the amortization period for such costs, if capitalized, would have been one Net Income Per Share Basic net income per share attributable to common stockholders is calculated by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net income per share is computed using the weighted average number of common shares outstanding during the period and, when dilutive, potential common share equivalents. Potentially dilutive common shares consist of shares issuable from restricted stock units, warrants, and our senior convertible notes. Potentially dilutive common shares issuable upon vesting of restricted stock units and exercise of warrants are determined using the average share price for each period under the treasury stock method. Potentially dilutive common shares issuable upon conversion of our senior convertible notes are determined using the if-converted method. In periods of net losses, we exclude all potentially dilutive common shares from the computation of the diluted net loss per share for those periods as the effect would be anti-dilutive. The following table sets forth the computation of basic and diluted net income per share for the periods shown. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Net income $ 62.9 $ 46.3 $ 103.2 $ 66.2 Net income per common share Basic $ 0.65 $ 0.49 $ 1.07 $ 0.71 Diluted $ 0.63 $ 0.48 $ 1.04 $ 0.69 Basic weighted average shares outstanding 96.7 93.8 96.5 92.8 Dilutive potential common stock outstanding: Restricted stock units 0.4 0.9 0.5 1.1 Warrants 2.5 2.3 2.5 1.7 Senior convertible notes — — — — Diluted weighted average shares outstanding 99.6 97.0 99.5 95.6 Outstanding anti-dilutive securities not included in the diluted net income per share attributable to common stockholders calculations were as follows: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Restricted stock units — — — 0.1 Warrants — — — — Senior convertible notes 7.2 8.7 7.2 9.5 Total 7.2 8.7 7.2 9.6 Recent Accounting Guidance Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects of the income tax accounting guidance, including requirements such as tax basis step-up in goodwill obtained in a transaction that is not a business combination, ownership changes in investments, and interim-period accounting for enacted changes in tax law. ASU 2019-12 is effective for public business entities for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years, and early adoption is permitted. Our adoption of ASU 2019-12 at the beginning of the first quarter of 2021 did not have a significant impact on our consolidated financial statements. Recently Issued Accounting Pronouncements Not Yet Adopted In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) . This new guidance is intended to reduce the complexity of accounting for convertible instruments. The guidance also addresses how convertible instruments are accounted for in the diluted earnings per share calculation and requires enhanced disclosures about the terms of convertible instruments. Entities may adopt ASU 2020-06 using either a partial retrospective or fully retrospective method of transition. This ASU is effective for public business entities for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. We are currently evaluating the impact that this guidance will have on our consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	2. Fair Value Measurements Assets and Liabilities Measured at Fair Value on a Recurring Basis We estimate the fair value of our Level 1 financial instruments, which are in active markets, using unadjusted quoted market prices for identical instruments. We obtain the fair values for our Level 2 financial instruments, which are not in active markets, from a primary professional pricing source that uses quoted market prices for identical or comparable instruments, rather than direct observations of quoted prices in active markets. Fair values obtained from this professional pricing source can also be based on pricing models whereby all significant observable inputs, including maturity dates, issue dates, settlement dates, benchmark yields, reported trades, broker-dealer quotes, issue spreads, benchmark securities, bids, offers or other market related data, are observable or can be derived from, or corroborated by, observable market data for substantially the full term of the asset. We validate the quoted market prices provided by our primary pricing service by comparing the fair values of our Level 2 marketable securities portfolio balance provided by our primary pricing service against the fair values of our Level 2 marketable securities portfolio balance provided by our investment managers. The following table summarizes financial assets that we measured at fair value on a recurring basis as of June 30, 2021, classified in accordance with the fair value hierarchy: Fair Value Measurements Using (In millions) Level 1 Level 2 Level 3 Total Cash equivalents $ 961.1 $ — $ — $ 961.1 Debt securities, available for sale: U.S. government agencies — 1,057.3 — 1,057.3 Commercial paper — 261.8 — 261.8 Corporate debt — 107.0 — 107.0 Total debt securities, available for sale — 1,426.1 — 1,426.1 Other assets (1) 5.8 — — 5.8 Total assets measured at fair value on a recurring basis $ 966.9 $ 1,426.1 $ — $ 2,393.0 (1) Includes assets which are held pursuant to a deferred compensation plan for senior management, which consist mainly of mutual funds . The following table summarizes financial assets that we measured at fair value on a recurring basis as of December 31, 2020, classified in accordance with the fair value hierarchy: Fair Value Measurements Using (In millions) Level 1 Level 2 Level 3 Total Cash equivalents $ 491.5 $ 150.0 $ — $ 641.5 Debt securities, available for sale: U.S. government agencies — 1,570.4 — 1,570.4 Commercial paper — 258.8 — 258.8 Corporate debt — 60.9 — 60.9 Total debt securities, available for sale — 1,890.1 — 1,890.1 Other assets (1) 3.4 — — 3.4 Total assets measured at fair value on a recurring basis $ 494.9 $ 2,040.1 $ — $ 2,535.0 (1) Includes assets which are held pursuant to a deferred compensation plan for senior management, which consist mainly of mutual funds. There were no transfers into or out of Level 3 securities during the three and six months ended June 30, 2021. We hold certain other investments that we do not measure at fair value on a recurring basis. The carrying values of these investments are not significant and we include them in other assets in our consolidated balance sheets. It is impracticable for us to estimate the fair value of these investments on a recurring basis due to the fact that these entities are privately held and limited information is available. We monitor the information that becomes available from time to time and adjust the carrying values of these investments if there are identified events or changes in circumstances that have a significant adverse effect on the fair values. Fair Value of Senior Convertible Notes The fair value, based on trading prices (Level 1), of our senior convertible notes were as follows as of the dates indicated: Fair Value Measurements Using Level 1 (In millions) June 30, 2021 December 31, 2020 Senior Convertible Notes due 2023 $ 2,210.9 $ 1,936.4 Senior Convertible Notes due 2025 1,264.1 1,219.2 Total fair value of outstanding senior convertible notes $ 3,475.0 $ 3,155.6 For more information on the carrying values of our senior convertible notes, see Note 4, “Debt.” Foreign Currency and Derivative Financial Instruments From time to time we engage in hedging transactions to reduce foreign currency risks. The fair values of these derivatives are based on quoted market prices, which are Level 1 inputs, and the derivative instruments are recorded in current assets or current liabilities in our consolidated balance sheets consistent with the nature of the instrument at period end. Derivative gains and losses are included in interest and other income, net in our consolidated statements of operations. As of June 30, 2021 and December 31, 2020, notional amounts of $52.0 million and $48.0 million, respectively, were outstanding to hedge certain foreign currency risk. The resulting impact on our consolidated financial statements from currency hedging activities was not significant for the three and six months ended June 30, 2021 or 2020. Our foreign currency exposures vary but are primarily concentrated primarily in the British Pound, the Euro, and the Canadian Dollar. We monitor the costs and the impact of foreign currency risks upon our financial results as part of our risk management program. We do not use derivative financial instruments for speculation or trading purposes or for activities other than risk management. We do not require and are not required to pledge collateral for these financial instruments and we do not carry any master netting arrangements to mitigate the credit risk. Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis In accordance with authoritative guidance, we measure certain non-financial assets and liabilities at fair value on a non-recurring basis. These measurements are usually performed using the discounted cash flow method or cost method and Level 3 inputs. These include items such as non-financial assets and liabilities initially measured at fair value in a business combination and non-financial long-lived assets measured at fair value for an impairment assessment. In general, non-financial assets, including goodwill, intangible assets, and property and equipment, are measured at fair value when there are indicators of impairment and are recorded at fair value only when any impairment is recognized. We recorded no significant impairment losses during the three and six months ended June 30, 2021 and 2020.

Balance Sheet Details

Balance Sheet Details	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Details	3. Balance Sheet Details Short-Term Marketable Securities Short-term marketable securities, consisting of debt securities, were as follows as of the dates indicated: June 30, 2021 (In millions) Amortized Gross Gross Estimated Debt securities, available for sale: U.S. government agencies $ 1,057.3 $ 0.1 $ (0.1) $ 1,057.3 Commercial paper 261.8 — — 261.8 Corporate debt 107.1 — (0.1) 107.0 Total debt securities, available for sale $ 1,426.2 $ 0.1 $ (0.2) $ 1,426.1 December 31, 2020 (In millions) Amortized Gross Gross Estimated Debt securities, available for sale: U.S. government agencies $ 1,570.4 $ 0.1 $ (0.1) $ 1,570.4 Commercial paper 258.7 0.1 — 258.8 Corporate debt 60.9 — — 60.9 Total debt securities, available for sale $ 1,890.0 $ 0.2 $ (0.1) $ 1,890.1 As of June 30, 2021 and December 31, 2020, all of our debt securities had contractual maturities of less than 12 months. Gross realized gains and losses on sales of our debt securities for the three and six months ended June 30, 2021 and June 30, 2020 were not significant. We periodically review our portfolio of debt securities to determine if any investment is impaired due to credit loss or other potential valuation concerns. For debt securities where the fair value of the investment is less than the amortized cost basis, we have assessed at the individual security level for various quantitative factors including, but not limited to, the nature of the investments, changes in credit ratings, interest rate fluctuations, industry analyst reports, and the severity of impairment. Unrealized losses on available-for-sale debt securities at June 30, 2021 were not significant and were primarily due to changes in interest rates, including market credit spreads, and not due to increased credit risks associated with specific securities. Accordingly, we have not recorded an allowance for credit losses. We do not intend to sell these investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases, which may be at maturity. Inventory (In millions) June 30, 2021 December 31, 2020 Raw materials $ 104.6 $ 69.9 Work-in-process 13.6 14.2 Finished goods 201.1 150.6 Total inventory $ 319.3 $ 234.7 Property and Equipment (In millions) June 30, 2021 December 31, 2020 Land (1) $ 15.6 $ 15.6 Building (1) 49.1 49.2 Furniture and fixtures 21.9 15.3 Computer software and hardware 39.3 35.7 Machinery and equipment 236.4 198.9 Leasehold improvements 225.0 135.8 Construction in progress 275.5 219.0 Total cost 862.8 669.5 Less accumulated depreciation and amortization (186.8) (154.2) Total property and equipment, net $ 676.0 $ 515.3 (1 ) Represents finance lease right-of-use assets. Accounts Payable and Accrued Liabilities (In millions) June 30, 2021 December 31, 2020 Accounts payable trade $ 165.9 $ 163.3 Accrued tax, audit, and legal fees 17.9 15.3 Accrued rebates 237.4 247.0 Accrued warranty 11.2 11.7 Other accrued liabilities 49.6 43.8 Total accounts payable and accrued liabilities $ 482.0 $ 481.1 Accrued Payroll and Related Expenses (In millions) June 30, 2021 December 31, 2020 Accrued wages, bonus and taxes $ 64.6 $ 87.7 Other accrued employee benefits 33.5 26.6 Total accrued payroll and related expenses $ 98.1 $ 114.3 Other Long-Term Liabilities (In millions) June 30, 2021 December 31, 2020 Finance lease obligations $ 57.4 $ 54.0 Contractual obligations 12.6 12.6 Other liabilities 17.7 14.3 Total other long-term liabilities $ 87.7 $ 80.9

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	4. Debt Senior Convertible Notes The carrying amounts of our senior convertible notes were as follows as of the dates indicated: (Dollars in millions) June 30, 2021 December 31, 2020 Principal amount: Senior Convertible Notes due 2023 $ 850.0 $ 850.0 Senior Convertible Notes due 2025 1,207.5 1,207.5 Total principal amount 2,057.5 2,057.5 Unamortized debt discount (329.8) (371.1) Unamortized debt issuance costs (17.0) (19.2) Carrying amount of liability component $ 1,710.7 $ 1,667.2 Carrying amount of equity component $ 461.0 $ 461.0 Remaining amortization period of debt discount on the liability component: Senior Convertible Notes due 2023 2.4 years 2.9 years Senior Convertible Notes due 2025 4.4 years 4.9 years For our senior convertible notes for which the if-converted value exceeded the principal amount, the amount in excess of principal was as follows as of the dates indicated: (In millions) June 30, 2021 December 31, 2020 Senior Convertible Notes due 2023 $ 1,364.0 $ 1,077.5 Senior Convertible Notes due 2025 8.8 — Total by which the notes ’ if-converted value exceeds their principal amount $ 1,372.8 $ 1,077.5 The following table summarizes the components of interest expense and the effective interest rates for each of our senior convertible notes for the periods shown. Three Months Ended Six Months Ended (Dollars in millions) 2021 2020 2021 2020 Cash interest expense: Contractual coupon interest (1),(2) $ 2.2 $ 2.4 $ 4.6 $ 4.7 Non-cash interest expense: Accretion of debt discount 20.8 16.5 41.3 28.3 Amortization of debt issuance costs 1.1 1.1 2.2 2.0 Total interest expense recognized on senior notes $ 24.1 $ 20.0 $ 48.1 $ 35.0 Effective interest rates: Senior Convertible Notes due 2022 (2) * 5.1 % * 5.1 % Senior Convertible Notes due 2023 5.6 % 5.6 % 5.6 % 5.6 % Senior Convertible Notes due 2025 5.5 % 5.5 % 5.5 % 5.5 % (1) Interest on the 2022 Notes began accruing upon issuance and was payable semi-annually on May 15 and November 15 of each year. Interest on the 2023 Notes began accruing upon issuance and is payable semi-annually on June 1 and December 1 of each year. Interest on the 2025 Notes began accruing upon issuance and is payable semi-annually on May 15 and November 15 of each year. (2) Our $400.0 million aggregate principal amount of unsecured senior convertible notes issued in June 2017 with a stated interest rate of 0.75% and maturity date of May 15, 2022 (the 2022 Notes) were repurchased and converted by August 2020. * Not applicable as no notes were outstanding at this date. Repurchase, Conversion, and Redemption of 2022 Notes In May 2020, we used approximately $282.6 million of the net proceeds from the 2025 Notes offering described below and issued 1,953,067 shares of Dexcom common stock to repurchase $260.0 million principal amount outstanding of the 2022 Notes and the associated conversion feature of the repurchased noted (which was recorded in additional paid-in capital). In addition, holders of 2022 Notes with a principal amount of $102.8 million exercised their option to convert their 2022 Notes during the three months ended June 30, 2020. We settled these conversions by issuing 1,037,319 shares of our common stock. As a result of the repurchase and conversions of the 2022 Notes, we recorded a loss on extinguishment of debt of $5.4 million for the three and six months ended June 30, 2020. The loss on extinguishment of debt includes the unamortized debt issuance costs for the 2022 Notes. 0.75% Senior Convertible Notes due 2023 In November 2018, we completed an offering of $850.0 million aggregate principal amount of unsecured senior convertible notes with a stated interest rate of 0.75% and a maturity date of December 1, 2023 (the 2023 Notes). The net proceeds from the offering, after deducting initial purchasers’ discounts and costs directly related to the offering, were approximately $836.6 million. The initial conversion rate of the 2023 Notes is 6.0869 shares per $1,000 principal amount of notes, which is equivalent to a conversion price of approximately $164.29 per share, subject to adjustments. We entered into transactions for a convertible note hedge (the 2023 Note Hedge) and warrants (the 2023 Warrants) concurrently with the issuance of the 2023 Notes. The 2023 Notes may be settled in cash, stock, or a combination thereof, solely at our discretion. We use the if-converted method for assumed conversion of the 2023 Notes to compute the weighted average shares of common stock outstanding for diluted earnings per share. Since upon conversion by the holders we may elect to settle such conversion in shares of our common stock, cash, or a combination thereof, we accounted for the cash conversion option as an equity instrument classified to stockholders’ equity. As a result, we recognized $171.6 million in additional paid-in capital, net of debt issuance costs, during 2018. No principal payments are due on the 2023 Notes prior to maturity. Other than restrictions relating to certain fundamental changes and consolidations, mergers or asset sales and customary anti-dilution adjustments, the indenture relating to the 2023 Notes includes customary terms and covenants, including certain events of default after which the 2023 Notes may be due and payable immediately. Conversion Rights at the Option of the Holders Holders of the 2023 Notes have the right to require us to repurchase for cash all or a portion of their notes at 100% of their principal amount, plus any accrued and unpaid interest, upon the occurrence of a fundamental change (as defined in the indenture relating to the notes). We will also be required to increase the conversion rate for holders who convert their 2023 Notes in connection with certain fundamental changes occurring prior to the maturity date or following the delivery by Dexcom of a notice of redemption. Holders of the 2023 Notes may convert all or a portion of their notes at their option prior to 5:00 p.m., New York City time, on the business day immediately preceding September 1, 2023, in multiples of $1,000 principal amount, only under the following circumstances: (1) during any calendar quarter commencing after March 31, 2019 (and only during such calendar quarter), if the last reported sale price of Dexcom’s common stock for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the applicable conversion price of the 2023 Notes on each such trading day; (2) during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of the 2023 Notes for each day of that five-day consecutive trading day period was less than 98% of the product of the last reported sale price of Dexcom’s common stock and the applicable conversion rate of the 2023 Notes on such trading day; (3) if we call any or all of the 2023 Notes for redemption, at any time prior to the close of business on the scheduled trading day immediately preceding the redemption date; or (4) upon the occurrence of specified corporate transactions. On or after September 1, 2023, until 5:00 p.m., New York City time, on the second scheduled trading day immediately preceding the maturity date, holders of the 2023 Notes may convert all or a portion of their notes regardless of the foregoing circumstances. Circumstance (1) listed above occurred during the quarters ended December 31, 2020 and March 31, 2021. As a result, the 2023 Notes were convertible at the option of the holder from January 1, 2021 through June 30, 2021; actual conversions during that period were not significant. Circumstance (1) listed above also occurred during the quarter ended June 30, 2021 and as a result, the 2023 Notes will remain convertible at the option of the holder from July 1, 2021 through September 30, 2021. Conversion Rights at Our Option Dexcom may not redeem the 2023 Notes prior to December 1, 2021. On or after December 1, 2021 and prior to September 1, 2023, Dexcom may redeem for cash all or part of the 2023 Notes, at its option, if the last reported sale price of our common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which Dexcom provides notice of redemption. The redemption price will be equal to 100% of the principal amount of the 2023 Notes to be redeemed plus accrued and unpaid interest to, but excluding, the redemption date. 2023 Note Hedge In connection with the offering of the 2023 Notes, in November 2018 we entered into convertible note hedge transactions with two of the initial purchasers of the 2023 Notes (the 2023 Counterparties) entitling us to purchase up to 5.2 million shares of our common stock at an initial price of $164.29 per share, each of which is subject to adjustment. The cost of the 2023 Note Hedge was $218.9 million and we accounted for it as an equity instrument by recognizing $218.9 million in additional paid-in capital during 2018. The 2023 Note Hedge will expire on December 1, 2023. The 2023 Note Hedge is expected to reduce the potential equity dilution upon any conversion of the 2023 Notes and/or offset any cash payments we are required to make in excess of the principal amount of converted 2023 Notes if the daily volume-weighted average price per share of our common stock exceeds the strike price of the 2023 Note Hedge. The strike price of the 2023 Note Hedge initially corresponds to the conversion price of the 2023 Notes and is subject to certain adjustments under the terms of the 2023 Note Hedge. An assumed exercise of the 2023 Note Hedge by us is considered anti-dilutive since the effect of the inclusion would always be anti-dilutive with respect to the calculation of diluted earnings per share. 2023 Warrants In November 2018, we also sold warrants to the 2023 Counterparties to acquire up to 5.2 million shares of our common stock. The 2023 Warrants require net share settlement and a pro rated number of warrants will expire on each of the 60 scheduled trading days starting on March 1, 2024. We received $183.8 million in cash proceeds from the sale of the 2023 Warrants, which we recorded in additional paid-in capital during 2018. The 2023 Warrants could have a dilutive effect on our earnings per share to the extent that the price of our common stock during a given measurement period exceeds the strike price of the 2023 Warrants. The strike price of the 2023 Warrants is initially $198.38 per share and is subject to certain adjustments under the terms of the warrant agreements. We use the treasury share method for assumed conversion of the 2023 Warrants when computing the weighted average common shares outstanding for diluted earnings per share. 0.25% Senior Convertible Notes due 2025 In May 2020, we completed an offering of $1.21 billion aggregate principal amount of unsecured senior convertible notes with a stated interest rate of 0.25% and a maturity date of November 15, 2025 (the 2025 Notes). The net proceeds from the offering, after deducting initial purchasers’ discounts and estimated costs directly related to the offering, were approximately $1.19 billion. The initial conversion rate of the 2025 Notes is 1.6655 shares per $1,000 principal amount of notes, which is equivalent to a conversion price of approximately $600.42 per share, subject to adjustments, with a maximum conversion rate of 2.3732. The 2025 Notes may be settled in cash, stock, or a combination thereof, solely at our discretion. We use the if-converted method for assumed conversion of the 2025 Notes to compute the weighted average shares of common stock outstanding for diluted earnings per share. Since upon conversion by the holders we may elect to settle such conversion in shares of our common stock, cash, or a combination thereof, we accounted for the cash conversion option as an equity instrument classified to stockholders’ equity. As a result, we recognized $289.4 million in additional paid-in-capital, net of debt issuance costs, during 2020. No principal payments are due on the 2025 Notes prior to maturity. Other than restrictions relating to certain fundamental changes and consolidations, mergers or asset sales and customary anti-dilution adjustments, the indenture relating to the 2025 Notes includes customary terms and covenants, including certain events of default after which the 2025 Notes may be due and payable immediately. Conversion Rights at the Option of the Holders In the event of a fundamental change (as defined in the indenture related to the 2025 Notes), holders of the 2025 Notes have the right to require us to repurchase for cash all or a portion of their notes at a price equal to 100% of the principal amount of the 2025 Notes, plus any accrued and unpaid interest. Holders of the 2025 Notes who convert their notes in connection with a make-whole fundamental change (as defined in the indenture) or following the delivery by Dexcom of a notice of redemption are, under certain circumstances, entitled to an increase in the conversion rate. Prior to 5:00 p.m., New York City time, on the business day immediately preceding August 15, 2025, holders of the 2025 Notes may convert all or a portion of their notes, in multiples of $1,000 principal amount, only under the following circumstances: (1) during any calendar quarter commencing after September 30, 2020 (and only during such calendar quarter), if the last reported sale price of Dexcom’s common stock for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the applicable conversion price of the Notes on each such trading day; (2) during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of the Notes for each day of that five day consecutive trading day period was less than 98% of the product of the last reported sale price of Dexcom’s common stock and the applicable conversion rate of the Notes on such trading day; (3) if we call any or all of the Notes for redemption, at any time prior to the close of business on the scheduled trading day immediately preceding the redemption date; or (4) upon the occurrence of specified corporate transactions. On or after August 15, 2025, until 5:00 p.m., New York City time, on the business day immediately preceding the maturity date, holders of the 2025 Notes may convert all or a portion of their notes regardless of the foregoing circumstances. Conversion Rights at Our Option Dexcom may not redeem the 2025 Notes prior to May 20, 2023. On or after May 20, 2023 and prior to August 15, 2025, Dexcom may redeem for cash all or part of the 2025 Notes, at its option, if the last reported sale price of our common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which Dexcom provides notice of redemption. The redemption price will be equal to 100% of the principal amount of the 2025 Notes to be redeemed plus accrued and unpaid interest to, but excluding, the redemption date. Revolving Credit Agreement Terms of the Revolving Credit Agreement On December 19, 2018, we entered into an amended and restated revolving credit agreement which was subsequently amended on May 11, 2020 (as amended, the Credit Agreement). The Credit Agreement provides for available principal amount of $200.0 million which can be increased up to $500.0 million at our option subject to customary conditions and approval of our lenders. Borrowings under the Credit Agreement are available for general corporate purposes, including working capital and capital expenditures. Information related to availability and outstanding borrowings on our Credit Agreement is as follows as of the date indicated: (In millions) June 30, 2021 Available principal amount $ 200.0 Letters of credit sub-facility 10.0 Outstanding borrowings — Outstanding letters of credit 6.4 Total available balance $ 193.6 Revolving loans under the Credit Agreement bear interest at our choice of one of two base rates plus a range of applicable margin rates that are based on our leverage ratio. The first base rate is the highest of (a) the publicly announced JPMorgan Chase prime rate, (b) the federal funds rate, or (c) the overnight bank funding rate, and the applicable margin rate ranges from 0.375% to 1.000%. The second base rate is a LIBOR-based rate, and the applicable margin rate ranges from 1.375% to 2.000%. We will also pay a commitment fee of between 0.2% and 0.3%, payable quarterly in arrears, on the average daily unused amount of the revolving facility based on our leverage ratio. The Credit Agreement will mature on the earlier to occur of (i) December 19, 2023, (ii) 91 days prior to the maturity date of the 2022 Notes or (iii) 91 days prior to the maturity date of the 2023 Notes if both (a) the aggregate outstanding principal amount of the 2022 Notes or the 2023 Notes, as applicable, is greater than EBITDA for the period of four consecutive fiscal quarters ending prior to such date and (b) unrestricted domestic cash on hand is less than the aggregate outstanding principal amount of the 2022 Notes or the 2023 Notes, as applicable, plus $100.0 million. Our obligations under the Credit Agreement are guaranteed by our existing and future wholly-owned domestic subsidiaries, and are secured by a first-priority security interest in substantially all of the assets of Dexcom and the guarantors, including all or a portion of the equity interests of our domestic subsidiaries and first-tier foreign subsidiaries but excluding real property and intellectual property (which is subject to a negative pledge). The Credit Agreement contains covenants that limit certain indebtedness, liens, investments, transactions with affiliates, dividends and other restricted payments, subordinated indebtedness and amendments to subordinated indebtedness documents, and sale and leaseback transactions of Dexcom or any of its domestic subsidiaries. The Credit Agreement also requires us to maintain a maximum leverage ratio and a minimum fixed charge coverage ratio. We were in compliance with these covenants as of June 30, 2021.

Contingencies

Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Contingencies	5. Contingencies Litigation We are subject to various claims, complaints and legal actions that arise from time to time in the normal course of business, including commercial insurance, product liability, intellectual property and employment related matters. In addition, from time to time we may bring claims or initiate lawsuits against various third parties with respect to matters arising out of the ordinary course of our business, including commercial and employment related matters. During the quarter ended June 30, 2021 and the third quarter of 2021, we and certain Abbott entities served complaints for patent infringement against each other in multiple jurisdictions, inside and outside the United States. We intend to vigorously pursue our claims and defenses in these cases to protect our intellectual property and to defend against Abbott’s infringement allegations.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	6. Income Taxes We estimate our annual effective tax rate to be 27.1% for the full year 2021, which differed from the U.S. federal statutory rate due to state and foreign income taxes, nondeductible executive compensation, and increases to unrecognized tax benefits offset by federal research tax credits generated. Our negative effective tax rate of 5.4% for the six months ended June 30, 2021 was due to excess tax benefits recognized for employee share-based compensation and a one-time tax benefit related to the revaluation of our U.K. net operating loss deferred tax asset resulting from the increase in the U.K. corporate tax rate from 19% to 25% effective April 2023. We operate in various jurisdictions outside of the U.S., many of which are enacting Anti-Tax Avoidance Directive (ATAD) laws that may impact our ability to deduct certain costs, which could potentially affect our estimated annual effective tax rate. We have made certain estimations and assumptions in determining the estimated annual effective tax rate, including the impact of these laws, the final application of which may differ from our estimates.

Stockholders' Equity

Stockholders' Equity	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Stockholders' Equity	7. Stockholders’ Equity Share-Based Compensation Our share-based compensation expense is associated with restricted stock units, or RSUs, performance stock units, or PSUs, and our Employee Stock Purchase Plan, or ESPP. The following table summarizes our share-based compensation expense included in our consolidated statements of operations for the periods shown. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Cost of sales $ 2.6 $ 4.1 $ 4.6 $ 6.0 Research and development 11.1 9.8 21.5 18.0 Selling, general and administrative 17.9 16.8 33.5 30.6 Total share-based compensation expense $ 31.6 $ 30.7 $ 59.6 $ 54.6 At June 30, 2021, unrecognized estimated compensation costs related to RSUs, PSUs and ESPP totaled $210.9 million and is expected to be recognized through 2024. Equity Award Activity The total vest date fair value of RSUs and PSUs that vested during the six months ended June 30, 2021 was $198.6 million and $29.5 million, respectively.

Business Segment and Geographic

Business Segment and Geographic Information	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Business Segment and Geographic Information	8. Business Segment and Geographic Information Reportable Segments An operating segment is identified as a component of a business that has discrete financial information available and for which the chief operating decision maker must decide the level of resource allocation. In addition, the guidance for segment reporting indicates certain quantitative materiality thresholds. None of the components of our business meet the definition of an operating segment. We currently consider our operations to be, and manage our business globally within, one reportable segment, which is consistent with how our President and Chief Executive Officer, who is our chief operating decision maker, reviews our business, makes investment and resource allocation decisions, and assesses operating performance. Disaggregation of Revenue We disaggregate revenue by geographic region and by major sales channel. We have determined that disaggregating revenue into these categories achieves the ASC Topic 606 disclosure objectives of depicting how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors. Dexcom is domiciled in the United States. We sell our CGM systems through a direct sales force in the United States, Canada and some countries in Europe, and through distribution arrangements in the United States, and certain countries in Africa, Asia, Europe, Latin America, and the Middle East, as well as Australia, Canada, and New Zealand. Revenues by geographic region During the three and six months ended June 30, 2021 and 2020, no individual country outside the United States generated revenue that represented more than 10% of our total revenue. The table below sets forth revenues by our two primary geographical markets, the United States and outside of the United States, based on the geographic location to which we deliver the components. The majority of our long-lived assets are located in the United States. Three Months Ended Three Months Ended (Dollars in millions) Amount % of Total Amount % of Total United States $ 461.5 78 % $ 367.1 81 % Outside of the United States 133.6 22 % 84.7 19 % Total revenues $ 595.1 100 % $ 451.8 100 % Six Months Ended Six Months Ended (Dollars in millions) Amount % of Total Amount % of Total United States $ 842.7 77 % $ 659.4 77 % Outside of the United States 257.4 23 % 197.5 23 % Total revenues $ 1,100.1 100 % $ 856.9 100 % Revenues by customer sales channel The following table sets forth revenues by major sales channel for the periods shown: Three Months Ended Three Months Ended (Dollars in millions) Amount % of Total Amount % of Total Distributor $ 495.9 83 % $ 331.7 73 % Direct 99.2 17 % 120.1 27 % Total revenues $ 595.1 100 % $ 451.8 100 % Six Months Ended Six Months Ended (Dollars in millions) Amount % of Total Amount % of Total Distributor $ 886.6 81 % $ 617.8 72 % Direct 213.5 19 % 239.1 28 % Total revenues $ 1,100.1 100 % $ 856.9 100 %

Organization and Significant _2

Organization and Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation and Principles of Consolidation We have prepared the accompanying unaudited consolidated financial statements in accordance with U.S. generally accepted accounting principles, or GAAP, for interim financial information and with the instructions to Form 10-Q and Article 10 of Securities and Exchange Commission, or SEC, Regulation S-X. Accordingly, they do not include all of the information and disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation, have been included. Operating results for the three and six months ended June 30, 2021 are not necessarily indicative of the results that may be expected for the year ending December 31, 2021. We expect that revenues we generate from the sales of our products will fluctuate from quarter to quarter. We experience seasonality that is typical in our industry, with lower sales in the first quarter of each year compared to the fourth quarter of the previous year. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes thereto for the year ended December 31, 2020 included in the Annual Report on Form 10-K that we filed with the SEC on February 11, 2021. These consolidated financial statements include the accounts of DexCom, Inc. and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We determine the functional currencies of our international subsidiaries by reviewing the environment where each subsidiary primarily generates and expends cash. For international subsidiaries whose functional currencies are the local currencies, we translate the financial statements into U.S. dollars using period-end exchange rates for assets and liabilities and average exchange rates for each period for revenue, costs and expenses. We include translation-related adjustments in comprehensive income and in accumulated other comprehensive income in the equity section of our consolidated balance sheets. We record gains and losses resulting from transactions with customers and vendors that are denominated in currencies other than the functional currency and from certain intercompany transactions in interest and other income, net in our consolidated statements of operations.
Principles of Consolidation	Basis of Presentation and Principles of Consolidation We have prepared the accompanying unaudited consolidated financial statements in accordance with U.S. generally accepted accounting principles, or GAAP, for interim financial information and with the instructions to Form 10-Q and Article 10 of Securities and Exchange Commission, or SEC, Regulation S-X. Accordingly, they do not include all of the information and disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation, have been included. Operating results for the three and six months ended June 30, 2021 are not necessarily indicative of the results that may be expected for the year ending December 31, 2021. We expect that revenues we generate from the sales of our products will fluctuate from quarter to quarter. We experience seasonality that is typical in our industry, with lower sales in the first quarter of each year compared to the fourth quarter of the previous year. These consolidated financial statements should be read in conjunction with the audited consolidated financial statements and related notes thereto for the year ended December 31, 2020 included in the Annual Report on Form 10-K that we filed with the SEC on February 11, 2021. These consolidated financial statements include the accounts of DexCom, Inc. and our wholly owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. We determine the functional currencies of our international subsidiaries by reviewing the environment where each subsidiary primarily generates and expends cash. For international subsidiaries whose functional currencies are the local currencies, we translate the financial statements into U.S. dollars using period-end exchange rates for assets and liabilities and average exchange rates for each period for revenue, costs and expenses. We include translation-related adjustments in comprehensive income and in accumulated other comprehensive income in the equity section of our consolidated balance sheets. We record gains and losses resulting from transactions with customers and vendors that are denominated in currencies other than the functional currency and from certain intercompany transactions in interest and other income, net in our consolidated statements of operations.
Use of Estimates	Use of Estimates
Accounts Receivable and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Accounts receivable are generally recorded at the invoiced amount for distributors and at net realizable value for direct customers, which is determined using estimates of claim denials and historical reimbursement experience without regard to aging category. Accounts receivable are not interest bearing. We evaluate the creditworthiness of significant customers based on historical trends, the financial condition of our customers, and external market factors. We generally do not require collateral from our customers. We maintain an allowance for doubtful accounts for potential credit losses. Uncollectible accounts are written off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a customer account is uncollectible. Generally, receivable balances greater than one year past due are deemed uncollectible.
Concentration of Credit Risk	Concentration of Credit Risk
Revenue Recognition	Revenue Recognition We generate our revenue from the sale of disposable sensors and our reusable transmitter and receiver, collectively referred to as Reusable Hardware. We also refer to Reusable Hardware in this section as Components. We generally recognize revenue when control is transferred to our customers in an amount that reflects the net consideration to which we expect to be entitled. In determining how revenue should be recognized, a five-step process is used, which includes identifying performance obligations in the contract, determining whether the performance obligations are separate, allocating the transaction price to each separate performance obligation, estimating the amount of variable consideration to include in the transaction price and determining the timing of revenue recognition for separate performance obligations. Contracts and Performance Obligations We consider customer purchase orders, which in most cases are governed by agreements with distributors or third-party payors, to be contracts with a customer. For each contract, we consider the obligation to transfer Components to the customer, each of which are distinct, to be separate performance obligations. We also provide free-of-charge software, mobile applications and updates for our Dexcom Share ® remote monitoring system. The standalone selling prices of Dexcom Share ® are estimated based on an expected cost plus a margin approach. Transaction Price Transaction price for the Components reflects the net consideration to which we expect to be entitled. Transaction price is typically based on the contracted rates less an estimate of claim denials and historical reimbursement experience by payor, which include current and future expectations regarding reimbursement rates and payor mix. Variable Consideration We include an estimate of variable consideration in the calculation of the transaction price at the time of sale, when control of the Components transfers to the customer. Variable consideration includes, but is not limited to: rebates, chargebacks, consideration payable to customers such as specialty distributor and wholesaler fees, product returns provision, prompt payment discounts, and various other promotional or incentive arrangements. We classify our provisions related to variable consideration as a reduction of accounts receivable when we are not required to make a payment or as a liability when we are required to make a payment. Rebates We are subject to rebates on pricing programs with managed care organizations, such as pharmacy benefit managers, governmental and third-party commercial payors, primarily in the U.S. We estimate provisions for rebates based on contractual arrangements, estimates of products sold subject to rebate, known events or trends and channel inventory data. Chargebacks We participate in chargeback programs, primarily with government entities in the U.S., under which pricing on products below negotiated list prices is provided to participating entities and equal to the difference between their acquisition cost and the lower negotiated price. We estimate provisions for chargebacks primarily based on historical experience on a product and program basis, current contract prices under the chargeback programs and channel inventory data. Consideration Payable to the Customer We pay administrative and service fees to certain of our distributors based on a fixed percentage of the product price. These fees are not in exchange for a distinct good or service and therefore are recognized as a reduction of the transaction price. We accrue for these fees based on actual net sales and contractual fee rates negotiated with the customer. Product Returns In accordance with the terms of their distribution agreements, most distributors do not have rights of return. The distributors typically have a limited time frame to notify us of any missing, damaged, defective or non-conforming products. We generally provide a “30-day money back guarantee” program whereby first-time end-user customers may return Reusable Hardware. We estimate our product returns provision principally based on historical experience by applying a historical return rate to the amounts of revenue estimated to be subject to returns. Additionally, we consider other specific factors such as estimated shelf life of inventory in the distribution channel and changes to customer terms. Prompt Payment Discounts We provide customers with prompt payment discounts which may result in adjustments to the price that is invoiced for the product transferred, in the case that payments are made within a defined period. We estimate prompt payment discount accruals based on actual net sales and contractual discount rates. Various Other Promotional or Incentive Arrangements Other promotional or incentive arrangements are periodically offered to customers, including but not limited to co-payment assistance we provide to patients with commercial insurance, promotional programs related to the launch of products or other targeted promotions. We record a provision for the incentive earned based on the number of estimated claims and our estimate of the cost per claim related to product sales that we have recognized as revenue. Revenue Recognition The timing of revenue recognition is based on the satisfaction of performance obligations. Substantially all of the performance obligations associated with our Components are satisfied at a point in time, which typically occurs at shipment of our products. Terms of direct and distributor orders are generally Freight on Board (FOB) shipping point for U.S. orders or Free Carrier (FCA) shipping point for international orders. For certain sales transactions, control transfers at delivery of the product to the customer. In cases where our free-of-charge software, mobile applications and updates are deemed to be separate performance obligations, revenue is recognized over time on a ratable basis over the estimated life of the related Reusable Hardware component. Our sales of Components include an assurance-type warranty. Contract Balances Contract balances represent amounts presented in our consolidated balance sheets when either we have transferred goods or services to the customer or the customer has paid consideration to us under the contract. These contract balances include accounts receivable and deferred revenue. Payment terms vary by contract type and type of customer and generally range from 30 to 90 days. Accounts receivable as of June 30, 2021 included unbilled accounts receivable of $11.1 million. We expect to invoice and collect all unbilled accounts receivable within 12 months. We record deferred revenue when we have entered into a contract with a customer and cash payments are received or due prior to transfer of control or satisfaction of the related performance obligation. Our performance obligations are generally satisfied within 12 months of the initial contract date. The deferred revenue balance related to performance obligations that will be satisfied after 12 months was $11.6 million as of June 30, 2021 and $8.2 million as of December 31, 2020. These balances are included in other long-term liabilities in our consolidated balance sheets. Revenue recognized in the period from performance obligations satisfied in previous periods was not material for the periods presented. Deferred Cost of Sales Deferred cost of sales are associated with transactions for which revenue recognition criteria are not met but product has shipped and released from inventory. Deferred cost of sales are included in prepaid and other current assets in our consolidated balance sheets. Incentive Compensation Costs one
Net Income Per Share	Net Income Per Share Basic net income per share attributable to common stockholders is calculated by dividing the net income attributable to common stockholders by the weighted-average number of common shares outstanding during the period. Diluted net income per share is computed using the weighted average number of common shares outstanding during the period and, when dilutive, potential common share equivalents. Potentially dilutive common shares consist of shares issuable from restricted stock units, warrants, and our senior convertible notes. Potentially dilutive common shares issuable upon vesting of restricted stock units and exercise of warrants are determined using the average share price for each period under the treasury stock method. Potentially dilutive common shares issuable upon conversion of our senior convertible notes are determined using the if-converted method. In periods of net losses, we exclude all potentially dilutive common shares from the computation of the diluted net loss per share for those periods as the effect would be anti-dilutive.
Recent Accounting Guidance	Recent Accounting Guidance Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects of the income tax accounting guidance, including requirements such as tax basis step-up in goodwill obtained in a transaction that is not a business combination, ownership changes in investments, and interim-period accounting for enacted changes in tax law. ASU 2019-12 is effective for public business entities for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years, and early adoption is permitted. Our adoption of ASU 2019-12 at the beginning of the first quarter of 2021 did not have a significant impact on our consolidated financial statements. Recently Issued Accounting Pronouncements Not Yet Adopted In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40) . This new guidance is intended to reduce the complexity of accounting for convertible instruments. The guidance also addresses how convertible instruments are accounted for in the diluted earnings per share calculation and requires enhanced disclosures about the terms of convertible instruments. Entities may adopt ASU 2020-06 using either a partial retrospective or fully retrospective method of transition. This ASU is effective for public business entities for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. Early adoption is permitted for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. We are currently evaluating the impact that this guidance will have on our consolidated financial statements.

Organization and Significant _3

Organization and Significant Accounting Policies (Tables)	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Basic and Diluted Net Income (Loss) per Share	The following table sets forth the computation of basic and diluted net income per share for the periods shown. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Net income $ 62.9 $ 46.3 $ 103.2 $ 66.2 Net income per common share Basic $ 0.65 $ 0.49 $ 1.07 $ 0.71 Diluted $ 0.63 $ 0.48 $ 1.04 $ 0.69 Basic weighted average shares outstanding 96.7 93.8 96.5 92.8 Dilutive potential common stock outstanding: Restricted stock units 0.4 0.9 0.5 1.1 Warrants 2.5 2.3 2.5 1.7 Senior convertible notes — — — — Diluted weighted average shares outstanding 99.6 97.0 99.5 95.6
Schedule of Outstanding Anti-dilutive Securities Excluded from Diluted Net Income (Loss) per Share	Outstanding anti-dilutive securities not included in the diluted net income per share attributable to common stockholders calculations were as follows: Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Restricted stock units — — — 0.1 Warrants — — — — Senior convertible notes 7.2 8.7 7.2 9.5 Total 7.2 8.7 7.2 9.6

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Fair Value Hierarchy for Financial Assets	The following table summarizes financial assets that we measured at fair value on a recurring basis as of June 30, 2021, classified in accordance with the fair value hierarchy: Fair Value Measurements Using (In millions) Level 1 Level 2 Level 3 Total Cash equivalents $ 961.1 $ — $ — $ 961.1 Debt securities, available for sale: U.S. government agencies — 1,057.3 — 1,057.3 Commercial paper — 261.8 — 261.8 Corporate debt — 107.0 — 107.0 Total debt securities, available for sale — 1,426.1 — 1,426.1 Other assets (1) 5.8 — — 5.8 Total assets measured at fair value on a recurring basis $ 966.9 $ 1,426.1 $ — $ 2,393.0 (1) Includes assets which are held pursuant to a deferred compensation plan for senior management, which consist mainly of mutual funds . The following table summarizes financial assets that we measured at fair value on a recurring basis as of December 31, 2020, classified in accordance with the fair value hierarchy: Fair Value Measurements Using (In millions) Level 1 Level 2 Level 3 Total Cash equivalents $ 491.5 $ 150.0 $ — $ 641.5 Debt securities, available for sale: U.S. government agencies — 1,570.4 — 1,570.4 Commercial paper — 258.8 — 258.8 Corporate debt — 60.9 — 60.9 Total debt securities, available for sale — 1,890.1 — 1,890.1 Other assets (1) 3.4 — — 3.4 Total assets measured at fair value on a recurring basis $ 494.9 $ 2,040.1 $ — $ 2,535.0 (1)
Schedule of Estimated Fair Values of Debt Instruments	The fair value, based on trading prices (Level 1), of our senior convertible notes were as follows as of the dates indicated: Fair Value Measurements Using Level 1 (In millions) June 30, 2021 December 31, 2020 Senior Convertible Notes due 2023 $ 2,210.9 $ 1,936.4 Senior Convertible Notes due 2025 1,264.1 1,219.2 Total fair value of outstanding senior convertible notes $ 3,475.0 $ 3,155.6 The carrying amounts of our senior convertible notes were as follows as of the dates indicated: (Dollars in millions) June 30, 2021 December 31, 2020 Principal amount: Senior Convertible Notes due 2023 $ 850.0 $ 850.0 Senior Convertible Notes due 2025 1,207.5 1,207.5 Total principal amount 2,057.5 2,057.5 Unamortized debt discount (329.8) (371.1) Unamortized debt issuance costs (17.0) (19.2) Carrying amount of liability component $ 1,710.7 $ 1,667.2 Carrying amount of equity component $ 461.0 $ 461.0 Remaining amortization period of debt discount on the liability component: Senior Convertible Notes due 2023 2.4 years 2.9 years Senior Convertible Notes due 2025 4.4 years 4.9 years

Balance Sheet Details (Tables)

Balance Sheet Details (Tables)	6 Months Ended
	Jun. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Short-term Marketable Securities	Short-term marketable securities, consisting of debt securities, were as follows as of the dates indicated: June 30, 2021 (In millions) Amortized Gross Gross Estimated Debt securities, available for sale: U.S. government agencies $ 1,057.3 $ 0.1 $ (0.1) $ 1,057.3 Commercial paper 261.8 — — 261.8 Corporate debt 107.1 — (0.1) 107.0 Total debt securities, available for sale $ 1,426.2 $ 0.1 $ (0.2) $ 1,426.1 December 31, 2020 (In millions) Amortized Gross Gross Estimated Debt securities, available for sale: U.S. government agencies $ 1,570.4 $ 0.1 $ (0.1) $ 1,570.4 Commercial paper 258.7 0.1 — 258.8 Corporate debt 60.9 — — 60.9 Total debt securities, available for sale $ 1,890.0 $ 0.2 $ (0.1) $ 1,890.1
Schedule of Inventory	(In millions) June 30, 2021 December 31, 2020 Raw materials $ 104.6 $ 69.9 Work-in-process 13.6 14.2 Finished goods 201.1 150.6 Total inventory $ 319.3 $ 234.7
Schedule of Property and Equipment	(In millions) June 30, 2021 December 31, 2020 Land (1) $ 15.6 $ 15.6 Building (1) 49.1 49.2 Furniture and fixtures 21.9 15.3 Computer software and hardware 39.3 35.7 Machinery and equipment 236.4 198.9 Leasehold improvements 225.0 135.8 Construction in progress 275.5 219.0 Total cost 862.8 669.5 Less accumulated depreciation and amortization (186.8) (154.2) Total property and equipment, net $ 676.0 $ 515.3 (1 ) Represents finance lease right-of-use assets.
Schedule of Accounts Payable and Accrued Liabilities	(In millions) June 30, 2021 December 31, 2020 Accounts payable trade $ 165.9 $ 163.3 Accrued tax, audit, and legal fees 17.9 15.3 Accrued rebates 237.4 247.0 Accrued warranty 11.2 11.7 Other accrued liabilities 49.6 43.8 Total accounts payable and accrued liabilities $ 482.0 $ 481.1
Schedule of Accrued Payroll and Related Expenses	(In millions) June 30, 2021 December 31, 2020 Accrued wages, bonus and taxes $ 64.6 $ 87.7 Other accrued employee benefits 33.5 26.6 Total accrued payroll and related expenses $ 98.1 $ 114.3
Schedule of Other Long-Term Liabilities	(In millions) June 30, 2021 December 31, 2020 Finance lease obligations $ 57.4 $ 54.0 Contractual obligations 12.6 12.6 Other liabilities 17.7 14.3 Total other long-term liabilities $ 87.7 $ 80.9

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments	The fair value, based on trading prices (Level 1), of our senior convertible notes were as follows as of the dates indicated: Fair Value Measurements Using Level 1 (In millions) June 30, 2021 December 31, 2020 Senior Convertible Notes due 2023 $ 2,210.9 $ 1,936.4 Senior Convertible Notes due 2025 1,264.1 1,219.2 Total fair value of outstanding senior convertible notes $ 3,475.0 $ 3,155.6 The carrying amounts of our senior convertible notes were as follows as of the dates indicated: (Dollars in millions) June 30, 2021 December 31, 2020 Principal amount: Senior Convertible Notes due 2023 $ 850.0 $ 850.0 Senior Convertible Notes due 2025 1,207.5 1,207.5 Total principal amount 2,057.5 2,057.5 Unamortized debt discount (329.8) (371.1) Unamortized debt issuance costs (17.0) (19.2) Carrying amount of liability component $ 1,710.7 $ 1,667.2 Carrying amount of equity component $ 461.0 $ 461.0 Remaining amortization period of debt discount on the liability component: Senior Convertible Notes due 2023 2.4 years 2.9 years Senior Convertible Notes due 2025 4.4 years 4.9 years
Schedule of Converted Value of Notes	For our senior convertible notes for which the if-converted value exceeded the principal amount, the amount in excess of principal was as follows as of the dates indicated: (In millions) June 30, 2021 December 31, 2020 Senior Convertible Notes due 2023 $ 1,364.0 $ 1,077.5 Senior Convertible Notes due 2025 8.8 — Total by which the notes ’ if-converted value exceeds their principal amount $ 1,372.8 $ 1,077.5
Schedule of Components of Interest Expense and Effective Interest Rates of Senior Convertible Notes	The following table summarizes the components of interest expense and the effective interest rates for each of our senior convertible notes for the periods shown. Three Months Ended Six Months Ended (Dollars in millions) 2021 2020 2021 2020 Cash interest expense: Contractual coupon interest (1),(2) $ 2.2 $ 2.4 $ 4.6 $ 4.7 Non-cash interest expense: Accretion of debt discount 20.8 16.5 41.3 28.3 Amortization of debt issuance costs 1.1 1.1 2.2 2.0 Total interest expense recognized on senior notes $ 24.1 $ 20.0 $ 48.1 $ 35.0 Effective interest rates: Senior Convertible Notes due 2022 (2) * 5.1 % * 5.1 % Senior Convertible Notes due 2023 5.6 % 5.6 % 5.6 % 5.6 % Senior Convertible Notes due 2025 5.5 % 5.5 % 5.5 % 5.5 % (1) Interest on the 2022 Notes began accruing upon issuance and was payable semi-annually on May 15 and November 15 of each year. Interest on the 2023 Notes began accruing upon issuance and is payable semi-annually on June 1 and December 1 of each year. Interest on the 2025 Notes began accruing upon issuance and is payable semi-annually on May 15 and November 15 of each year. (2) Our $400.0 million aggregate principal amount of unsecured senior convertible notes issued in June 2017 with a stated interest rate of 0.75% and maturity date of May 15, 2022 (the 2022 Notes) were repurchased and converted by August 2020. * Not applicable as no notes were outstanding at this date.
Schedule of Availability and Outstanding Borrowings on Credit Agreement	Information related to availability and outstanding borrowings on our Credit Agreement is as follows as of the date indicated: (In millions) June 30, 2021 Available principal amount $ 200.0 Letters of credit sub-facility 10.0 Outstanding borrowings — Outstanding letters of credit 6.4 Total available balance $ 193.6

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	6 Months Ended
	Jun. 30, 2021
Share-based Payment Arrangement [Abstract]
Schedule of Share-Based Compensation Expense	Our share-based compensation expense is associated with restricted stock units, or RSUs, performance stock units, or PSUs, and our Employee Stock Purchase Plan, or ESPP. The following table summarizes our share-based compensation expense included in our consolidated statements of operations for the periods shown. Three Months Ended Six Months Ended (In millions) 2021 2020 2021 2020 Cost of sales $ 2.6 $ 4.1 $ 4.6 $ 6.0 Research and development 11.1 9.8 21.5 18.0 Selling, general and administrative 17.9 16.8 33.5 30.6 Total share-based compensation expense $ 31.6 $ 30.7 $ 59.6 $ 54.6

Business Segment and Geograph_2

Business Segment and Geographic Information (Tables)	6 Months Ended
	Jun. 30, 2021
Segment Reporting [Abstract]
Schedule of Revenue from External Customers by Geographic Areas	The table below sets forth revenues by our two primary geographical markets, the United States and outside of the United States, based on the geographic location to which we deliver the components. The majority of our long-lived assets are located in the United States. Three Months Ended Three Months Ended (Dollars in millions) Amount % of Total Amount % of Total United States $ 461.5 78 % $ 367.1 81 % Outside of the United States 133.6 22 % 84.7 19 % Total revenues $ 595.1 100 % $ 451.8 100 % Six Months Ended Six Months Ended (Dollars in millions) Amount % of Total Amount % of Total United States $ 842.7 77 % $ 659.4 77 % Outside of the United States 257.4 23 % 197.5 23 % Total revenues $ 1,100.1 100 % $ 856.9 100 %
Schedule of Disaggregation of Revenue	The following table sets forth revenues by major sales channel for the periods shown: Three Months Ended Three Months Ended (Dollars in millions) Amount % of Total Amount % of Total Distributor $ 495.9 83 % $ 331.7 73 % Direct 99.2 17 % 120.1 27 % Total revenues $ 595.1 100 % $ 451.8 100 % Six Months Ended Six Months Ended (Dollars in millions) Amount % of Total Amount % of Total Distributor $ 886.6 81 % $ 617.8 72 % Direct 213.5 19 % 239.1 28 % Total revenues $ 1,100.1 100 % $ 856.9 100 %

Organization and Significant _4

Organization and Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Organization And Summary Of Significant Accounting Policies [Line Items]
Sales returns coverage period	30 days
Unbilled accounts receivable	$ 11.1
Noncurrent deferred revenue	$ 11.6	$ 8.2
Amortization period for incentive compensation costs	1 year
Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Contract payment term	30 days
Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Contract payment term	90 days

Organization and Significant _5

Organization and Significant Accounting Policies - Earnings Per Share, Basic and Diluted (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net income	$ 62.9	$ 46.3	$ 103.2	$ 66.2
Net income per common share
Basic (USD per share)	$ 0.65	$ 0.49	$ 1.07	$ 0.71
Diluted (USD per share)	$ 0.63	$ 0.48	$ 1.04	$ 0.69
Basic weighted average shares outstanding (in shares)	96.7	93.8	96.5	92.8
Diluted weighted average shares outstanding (in shares)	99.6	97	99.5	95.6
Restricted stock units
Net income per common share
Effect of potentially dilutive stock options (in shares)	0.4	0.9	0.5	1.1
Warrants
Net income per common share
Effect of potentially dilutive stock options (in shares)	2.5	2.3	2.5	1.7
Senior convertible notes
Net income per common share
Effect of potentially dilutive stock options (in shares)	0	0	0	0

Organization and Significant _6

Organization and Significant Accounting Policies - Anti-dilutive Securities Excluded from Calculation of Net Income (Loss) per Share (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (shares)	7.2	8.7	7.2	9.6
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (shares)	0	0	0	0.1
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (shares)	0	0	0	0
Senior convertible notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of net loss per share (shares)	7.2	8.7	7.2	9.5

Fair Value Measurements - Summa

Fair Value Measurements - Summary (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Cash equivalents	$ 961.1	$ 641.5
Debt securities, available for sale:	1,426.1	1,890.1
Other assets	5.8	3.4
Total assets measured at fair value on a recurring basis	2,393	2,535
U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	1,057.3	1,570.4
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	261.8	258.8
Corporate debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	107	60.9
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Cash equivalents	961.1	491.5
Debt securities, available for sale:	0	0
Other assets	5.8	3.4
Total assets measured at fair value on a recurring basis	966.9	494.9
Level 1 | U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	0	0
Level 1 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	0	0
Level 1 | Corporate debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	0	0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Cash equivalents	0	150
Debt securities, available for sale:	1,426.1	1,890.1
Other assets	0	0
Total assets measured at fair value on a recurring basis	1,426.1	2,040.1
Level 2 | U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	1,057.3	1,570.4
Level 2 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	261.8	258.8
Level 2 | Corporate debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	107	60.9
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Cash equivalents	0	0
Debt securities, available for sale:	0	0
Other assets	0	0
Total assets measured at fair value on a recurring basis	0	0
Level 3 | U.S. government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	0	0
Level 3 | Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	0	0
Level 3 | Corporate debt
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Debt securities, available for sale:	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers into or out of Level 3 securities	$ 0		$ 0
Goodwill and intangible asset impairment	0	$ 0	0	$ 0
Foreign Exchange Forward | Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Notional amount of derivative instrument	$ 52,000,000		$ 52,000,000		$ 48,000,000

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Convertible Senior Notes (Details) - Senior Notes - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Line Items]
Fair value of outstanding senior convertible notes:	$ 3,475	$ 3,155.6
Senior Convertible Notes due 2023
Fair Value Disclosures [Line Items]
Fair value of outstanding senior convertible notes:	2,210.9	1,936.4
Senior Convertible Notes due 2025
Fair Value Disclosures [Line Items]
Fair value of outstanding senior convertible notes:	$ 1,264.1	$ 1,219.2

Balance Sheet Details - Short-t

Balance Sheet Details - Short-term Marketable Securities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Debt securities, available for sale:
Amortized Cost	$ 1,426.2	$ 1,890
Gross Unrealized Gains	0.1	0.2
Gross Unrealized Losses	(0.2)	(0.1)
Estimated Market Value	1,426.1	1,890.1
U.S. government agencies
Debt securities, available for sale:
Amortized Cost	1,057.3	1,570.4
Gross Unrealized Gains	0.1	0.1
Gross Unrealized Losses	(0.1)	(0.1)
Estimated Market Value	1,057.3	1,570.4
Commercial paper
Debt securities, available for sale:
Amortized Cost	261.8	258.7
Gross Unrealized Gains	0	0.1
Gross Unrealized Losses	0	0
Estimated Market Value	261.8	258.8
Corporate debt
Debt securities, available for sale:
Amortized Cost	107.1	60.9
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(0.1)	0
Estimated Market Value	$ 107	$ 60.9

Balance Sheet Details - Narrati

Balance Sheet Details - Narrative (Details)	Jun. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Contractual maturities of debt securities (less than)	12 years	12 years

Balance Sheet Details - Invento

Balance Sheet Details - Inventory (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 104.6	$ 69.9
Work-in-process	13.6	14.2
Finished goods	201.1	150.6
Total inventory	$ 319.3	$ 234.7

Balance Sheet Details - Propert

Balance Sheet Details - Property and Equipment (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total cost	$ 862.8	$ 669.5
Less accumulated depreciation and amortization	(186.8)	(154.2)
Total property and equipment, net	676	515.3
Land
Property, Plant and Equipment [Line Items]
Total cost	15.6	15.6
Building
Property, Plant and Equipment [Line Items]
Total cost	49.1	49.2
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total cost	21.9	15.3
Computer software and hardware
Property, Plant and Equipment [Line Items]
Total cost	39.3	35.7
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total cost	236.4	198.9
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total cost	225	135.8
Construction in progress
Property, Plant and Equipment [Line Items]
Total cost	$ 275.5	$ 219

Balance Sheet Details - Account

Balance Sheet Details - Accounts Payable and Accrued Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Accounts Payable and Accrued Liabilities [Abstract]
Accounts payable trade	$ 165.9	$ 163.3
Accrued tax, audit, and legal fees	17.9	15.3
Accrued rebates	237.4	247
Accrued warranty	11.2	11.7
Other accrued liabilities	49.6	43.8
Total accounts payable and accrued liabilities	$ 482	$ 481.1

Balance Sheet Details - Accrued

Balance Sheet Details - Accrued Payroll and Related Expenses (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Employee-related Liabilities, Current [Abstract]
Accrued wages, bonus and taxes	$ 64.6	$ 87.7
Other accrued employee benefits	33.5	26.6
Total accrued payroll and related expenses	$ 98.1	$ 114.3

Balance Sheet Details - Other L

Balance Sheet Details - Other Long-Term Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Finance lease obligations	$ 57.4	$ 54
Contractual obligations	12.6	12.6
Other liabilities	17.7	14.3
Total other long-term liabilities	$ 87.7	$ 80.9

Debt - Senior Convertible Notes

Debt - Senior Convertible Notes (Details) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	May 31, 2020	Nov. 30, 2018
Senior Convertible Notes
Carrying amount of liability component	$ 1,710,700,000	$ 1,667,200,000
Senior Notes
Senior Convertible Notes
Principal amount	2,057,500,000	2,057,500,000
Unamortized debt discount	(329,800,000)	(371,100,000)
Unamortized debt issuance costs	(17,000,000)	(19,200,000)
Carrying amount of liability component	1,710,700,000	1,667,200,000
Carrying amount of equity component	461,000,000	461,000,000
Senior Notes | Senior Convertible Notes due 2023
Senior Convertible Notes
Principal amount	$ 850,000,000	$ 850,000,000		$ 850,000,000
Remaining amortization period of debt discount on the liability component:	2 years 4 months 24 days	2 years 10 months 24 days
Senior Notes | Senior Convertible Notes due 2025
Senior Convertible Notes
Principal amount	$ 1,207,500,000	$ 1,207,500,000	$ 1,210,000,000
Remaining amortization period of debt discount on the liability component:	4 years 4 months 24 days	4 years 10 months 24 days

Debt - Conversion Value of Conv

Debt - Conversion Value of Convertible Notes (Details) - Senior Notes - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Total by which the notes’ if-converted value exceeds their principal amount	$ 1,372.8	$ 1,077.5
Senior Convertible Notes due 2023
Debt Instrument [Line Items]
Total by which the notes’ if-converted value exceeds their principal amount	1,364	1,077.5
Senior Convertible Notes due 2025
Debt Instrument [Line Items]
Total by which the notes’ if-converted value exceeds their principal amount	$ 8.8	$ 0

Debt - Components of Interest E

Debt - Components of Interest Expense and Effective Interest Rates of Senior Convertible Notes (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020	May 31, 2020	Nov. 30, 2018	Jun. 30, 2017
Cash interest expense:
Contractual coupon interest	$ 2,200,000	$ 2,400,000	$ 4,600,000	$ 4,700,000
Non-cash interest expense:
Accretion of debt discount	20,800,000	16,500,000	41,300,000	28,300,000
Amortization of debt issuance costs	1,100,000	1,100,000	2,200,000	2,000,000
Total interest expense recognized on senior notes	24,100,000	$ 20,000,000	48,100,000	$ 35,000,000
Senior Notes
Non-cash interest expense:
Principal amount	$ 2,057,500,000		$ 2,057,500,000		$ 2,057,500,000
Senior Convertible Notes due 2022
Non-cash interest expense:
Effective interest rate (as a percent)		5.10%		5.10%
Senior Convertible Notes due 2022 | Senior Notes
Non-cash interest expense:
Principal amount						$ 260,000,000		$ 400,000,000
Interest rate on convertible notes (as a percent)								0.75%
Senior Convertible Notes due 2023
Non-cash interest expense:
Effective interest rate (as a percent)	5.60%	5.60%	5.60%	5.60%
Senior Convertible Notes due 2023 | Senior Notes
Non-cash interest expense:
Principal amount	$ 850,000,000		$ 850,000,000		850,000,000		$ 850,000,000
Interest rate on convertible notes (as a percent)							0.75%
Senior Convertible Notes due 2025
Non-cash interest expense:
Effective interest rate (as a percent)	5.50%	5.50%	5.50%	5.50%
Senior Convertible Notes due 2025 | Senior Notes
Non-cash interest expense:
Principal amount	$ 1,207,500,000		$ 1,207,500,000		$ 1,207,500,000	$ 1,210,000,000
Interest rate on convertible notes (as a percent)						0.25%

Debt - Narrative (Details)

Debt - Narrative (Details)	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	May 31, 2020USD ($)$ / sharesshares	Nov. 30, 2018USD ($)d$ / sharesshares	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)shares	Jun. 30, 2021USD ($)d	Jun. 30, 2020USD ($)shares	Dec. 31, 2020USD ($)	Dec. 31, 2018USD ($)	Dec. 19, 2018USD ($)	Jun. 30, 2017USD ($)
Debt Instrument [Line Items]
Payments to repurchase convertible notes	$ 282,600,000				$ 0	$ 282,600,000
Repurchase and conversions of 2022 Notes (in shares) | shares	1,953,067
Loss on extinguishment of debt			$ 0	$ 5,400,000	0	5,400,000
Proceeds from issuance of convertible notes, net of issuance costs					0	1,188,800,000
Equity component of 2025 Notes issuance, net of issuance costs				289,400,000		$ 289,400,000
Senior Notes
Debt Instrument [Line Items]
Principal amount			2,057,500,000		$ 2,057,500,000		$ 2,057,500,000
Senior Notes | Senior Convertible Notes due 2022
Debt Instrument [Line Items]
Principal amount	$ 260,000,000									$ 400,000,000
Debt instrument convertible principal amount exercised				$ (102,800,000)
Interest rate on convertible notes (as a percent)										0.75%
Redemption price (as a percent)					100.00%
Senior Notes | Senior Convertible Notes due 2023
Debt Instrument [Line Items]
Principal amount		$ 850,000,000	$ 850,000,000		$ 850,000,000		850,000,000
Interest rate on convertible notes (as a percent)		0.75%
Proceeds from issuance of convertible notes, net of issuance costs		$ 836,600,000
Conversion ratio		0.0060869
Conversion amount		$ 1,000
Conversion price of convertible notes (USD per share) | $ / shares		$ 164.29
Holder's repurchase price percentage in event of fundamental change (as a percent)			100.00%		100.00%
Number of trading days | d		60
Proportion of conversion price (as a percent)					130.00%
Redemption price (as a percent)					100.00%
Stock counterparties to acquire with warrants purchased (shares) | shares		5,200,000
Proceeds from sale of warrants		$ 183,800,000
Exercise price of warrants or rights (USD per share) | $ / shares		$ 198.38
Senior Notes | Senior Convertible Notes due 2023 | Designated as Hedging Instrument
Debt Instrument [Line Items]
Stock issued upon conversion of senior notes (in shares) | shares		5,200,000
Equity component of 2025 Notes issuance, net of issuance costs		$ 218,900,000
Senior Notes | Senior Convertible Notes due 2023 | Debt Instrument Conversion Term One | Minimum
Debt Instrument [Line Items]
Number of trading days | d					20
Proportion of applicable conversion price (as a percent)					130.00%
Senior Notes | Senior Convertible Notes due 2023 | Debt Instrument Conversion Term One | Maximum
Debt Instrument [Line Items]
Number of trading days | d					30
Senior Notes | Senior Convertible Notes due 2023 | Debt Instrument Conversion Term Two
Debt Instrument [Line Items]
Number of trading days | d					5
Senior Notes | Senior Convertible Notes due 2023 | Debt Instrument Conversion Term Two | Maximum
Debt Instrument [Line Items]
Number of trading days | d					5
Proportion of applicable conversion price (as a percent)					98.00%
Senior Notes | Senior Convertible Notes due 2025
Debt Instrument [Line Items]
Principal amount	$ 1,210,000,000		$ 1,207,500,000		$ 1,207,500,000		1,207,500,000
Interest rate on convertible notes (as a percent)	0.25%
Proceeds from issuance of convertible notes, net of issuance costs	$ 1,190,000,000
Conversion ratio	0.0016655
Conversion price of convertible notes (USD per share) | $ / shares	$ 600.42
Holder's repurchase price percentage in event of fundamental change (as a percent)			100.00%		100.00%
Proportion of conversion price (as a percent)					130.00%
Senior Notes | Senior Convertible Notes due 2025 | Designated as Hedging Instrument
Debt Instrument [Line Items]
Recognized additional paid-in capital from cash conversion option							$ 289,400,000
Senior Notes | Senior Convertible Notes due 2025 | Maximum
Debt Instrument [Line Items]
Conversion ratio	0.0023732
Senior Notes | Senior Convertible Notes due 2025 | Debt Instrument Conversion Term One | Minimum
Debt Instrument [Line Items]
Number of trading days | d					20
Proportion of applicable conversion price (as a percent)					130.00%
Senior Notes | Senior Convertible Notes due 2025 | Debt Instrument Conversion Term One | Maximum
Debt Instrument [Line Items]
Number of trading days | d					30
Senior Notes | Senior Convertible Notes due 2025 | Debt Instrument Conversion Term Two
Debt Instrument [Line Items]
Number of trading days | d					5
Senior Notes | Senior Convertible Notes due 2025 | Debt Instrument Conversion Term Two | Maximum
Debt Instrument [Line Items]
Number of trading days | d					5
Proportion of applicable conversion price (as a percent)					98.00%
Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity of revolving credit agreement			$ 200,000,000		$ 200,000,000				$ 200,000,000
Option to increase revolving line of credit									$ 500,000,000
Value of unrestricted cash on hand threshold					$ 100,000,000
Line of Credit | Minimum
Debt Instrument [Line Items]
Interest rate on convertible notes (as a percent)			0.375%		0.375%
Unused capacity fee (as a percent)					0.20%
Line of Credit | Minimum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					1.375%
Line of Credit | Maximum
Debt Instrument [Line Items]
Interest rate on convertible notes (as a percent)			1.00%		1.00%
Unused capacity fee (as a percent)					0.30%
Line of Credit | Maximum | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)					2.00%
Common Stock
Debt Instrument [Line Items]
Repurchase and conversions of 2022 Notes (in shares) | shares				3,000,000		3,000,000
Common Stock | Senior Notes | Senior Convertible Notes due 2022
Debt Instrument [Line Items]
Repurchase and conversions of 2022 Notes (in shares) | shares				1,037,319
Additional Paid-In Capital
Debt Instrument [Line Items]
Equity component of 2025 Notes issuance, net of issuance costs				$ 289,400,000		$ 289,400,000
Additional Paid-In Capital | Senior Notes | Senior Convertible Notes due 2023
Debt Instrument [Line Items]
Recognized additional paid-in capital from cash conversion option								$ 171,600,000

Debt - Availability and Outstan

Debt - Availability and Outstanding Borrowings under Credit Agreement (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 19, 2018
Line of Credit Facility [Line Items]
Total available balance	$ 193.6
Line of Credit
Line of Credit Facility [Line Items]
Letters of credit sub-facility	200	$ 200
Outstanding borrowings	0
Line of Credit | Letter of Credit
Line of Credit Facility [Line Items]
Letters of credit sub-facility	10
Outstanding letters of credit	$ 6.4

Income Taxes (Details)

Income Taxes (Details)	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Estimated annual effective tax rate (as a percent)	27.10%
Effective tax rate (as a percent)	(5.40%)

Stockholders' Equity - Share-Ba

Stockholders' Equity - Share-Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	$ 31.6	$ 30.7	$ 59.6	$ 54.6
Cost of sales
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	2.6	4.1	4.6	6
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	11.1	9.8	21.5	18
Selling, general and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total share-based compensation expense	$ 17.9	$ 16.8	$ 33.5	$ 30.6

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) $ in Millions	6 Months Ended
	Jun. 30, 2021USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized estimated compensation costs	$ 210.9
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total vest date fair value	198.6
Performance stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total vest date fair value	$ 29.5

Business Segment and Geograph_3

Business Segment and Geographic Information - Narrative (Details)	6 Months Ended
	Jun. 30, 2021segment
Segment Reporting [Abstract]
Number of reportable segments	1

Business Segment and Geograph_4

Business Segment and Geographic Information - Summary (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 595.1	$ 451.8	$ 1,100.1	$ 856.9
Proportion of revenue (as a percent)	100.00%	100.00%	100.00%	100.00%
Distributor
Disaggregation of Revenue [Line Items]
Revenues	$ 495.9	$ 331.7	$ 886.6	$ 617.8
Proportion of revenue (as a percent)	83.00%	73.00%	81.00%	72.00%
Direct
Disaggregation of Revenue [Line Items]
Revenues	$ 99.2	$ 120.1	$ 213.5	$ 239.1
Proportion of revenue (as a percent)	17.00%	27.00%	19.00%	28.00%
United States
Disaggregation of Revenue [Line Items]
Revenues	$ 461.5	$ 367.1	$ 842.7	$ 659.4
Proportion of revenue (as a percent)	78.00%	81.00%	77.00%	77.00%
Outside of the United States
Disaggregation of Revenue [Line Items]
Revenues	$ 133.6	$ 84.7	$ 257.4	$ 197.5
Proportion of revenue (as a percent)	22.00%	19.00%	23.00%	23.00%