Debt	12 Months Ended
Dec. 31, 2019
Debt Disclosure [Abstract]
Debt	Note 13—Debt 2019 Convertible Debt In September 2019, the Company issued $650.0 million aggregate principal amount of 0.125% Convertible Senior Notes due 2026 (the “2019 Notes”) in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”). The net proceeds from the sale of the 2019 Notes were $639.5 million after deducting the initial purchasers’ discount and offering expenses. The 2019 Notes are convertible based upon an initial conversion rate of 11.4040 shares of the Company’s common stock per $1,000 principal amount of 2019 Notes (equivalent to an initial conversion price of approximately $87.69 per share). The conversion rate will be subject to adjustment upon the occurrence of certain specified events, including certain distributions and dividends to all or substantially all of the holders of the Company’s common stock. The Company will settle any conversions of the 2019 Notes in cash, shares of the Company’s common stock, or a combination thereof, with the form of consideration determined at the Company’s election. The 2019 Notes will mature on October 1, 2026, unless earlier converted or repurchased. Prior to the close of business on the business day immediately preceding June 1, 2026, holders may convert all or a portion of their 2019 Notes only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on December 31, 2019 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the 5 business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of 2019 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; (3) with respect to any or all of the 2019 Notes called for redemption by the Company prior to the close of business on the business day immediately preceding June 1, 2026, holders may convert all or any portion of their 2019 Notes at any time prior to the close of business on the second scheduled trading day prior to the redemption date, even if the 2019 Notes are not otherwise convertible at such time; and (4) upon the occurrence of specified corporate events. On and after June 1, 2026 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their 2019 Notes at any time, regardless of the foregoing circumstances. As of December 31, 2019, the if-converted value of the 2019 Notes was approximately $321.6 million lower than the aggregate principal amount, or $328.4 million. If a fundamental change occurs prior to the maturity date, holders may require the Company to repurchase all or a portion of their 2019 Notes for cash at a price equal to 100% of the principal amount of the 2019 Notes to be repurchased. Holders of 2019 Notes who convert their 2019 Notes in connection with a notice of a redemption or a make-whole fundamental change may be entitled to a premium in the form of an increase in the conversion rate of the 2019 Notes. As of December 31, 2019, none of the conditions permitting the holders of the 2019 Notes to early convert have been met. The 2019 Notes are general unsecured obligations of the Company. The 2019 Notes rank senior in right of payment to all of the Company’s future indebtedness that is expressly subordinated in right of payment to the 2019 Notes; rank equal in right of payment with all of our liabilities that are not so subordinated, including our 0% Convertible Senior Notes due 2023 (the “2018 Notes”); are effectively junior to any of the Company’s secured indebtedness; and are structurally junior to all indebtedness and liabilities (including trade payables) of the Company’s subsidiaries. In accounting for the issuance of the 2019 Notes, the Company separated the 2019 Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component, representing the conversion option, which does not meet the criteria for separate accounting as a derivative as it is indexed to the Company’s own stock, was determined by deducting the fair value of the liability component from the par value of the 2019 Notes. The difference between the principal amount of the 2019 Notes and the liability component represents the debt discount, which is recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheet and accreted over the period from the date of issuance to the contractual maturity date, resulting in the recognition of non-cash interest expense. The equity component of the 2019 Notes of approximately $154.0 million is included in additional paid-in capital in the Consolidated Balance Sheet and is not remeasured as long as it continues to meet the conditions for equity classification. Transaction costs were allocated to the liability and equity components in the same proportion as the allocation of the proceeds. Transaction costs attributable to the liability component were recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheet and are amortized to interest expense using the effective interest method over the term of the 2019 Notes, and transaction costs attributable to the equity component were netted with the equity component in stockholders’ equity. The Company capitalized $10.5 million of debt issuance costs in connection with the 2019 Notes. Non-cash interest expense, including amortization of debt issuance costs, related to the 2019 Notes for the year ended December 31, 2019 was $5.6 million. Total unamortized debt issuance costs were $7.8 million as of December 31, 2019. The estimated fair value of the 2019 Notes was $522.2 million as of December 31, 2019. The estimated fair value of the 2019 Notes was determined through consideration of quoted market prices for similar instruments. The fair value is classified as Level 2, as defined in “Note 8—Fair Value Measurements.” 2019 Capped Call Transactions The Company used $76.2 million of the net proceeds from the 2019 Notes offering to enter into separate capped call transactions (“2019 Capped Call Transactions”) with the initial purchasers and/or their respective affiliates. The 2019 Capped Call Transactions are expected generally to reduce the potential dilution and/or offset the cash payments the Company is required to make in excess of the principal amount of the 2019 Notes upon conversion of the 2019 Notes in the event that the market price per share of the Company’s common stock is greater than the strike price of the 2019 Capped Call Transactions with such reduction and/or offset subject to a cap. The 2019 Capped Call Transactions have an initial cap price of $148.63 per share of the Company’s common stock, which represents a premium of 150% over the last reported sale price of the Company’s common stock on September 18, 2019, and is subject to certain adjustments under the terms of the 2019 Capped Call Transactions. Collectively, the 2019 Capped Call Transactions cover, initially, the number of shares of the Company’s common stock underlying the 2019 Notes, subject to anti-dilution adjustments substantially similar to those applicable to the 2019 Notes. The 2019 Capped Call Transactions do not meet the criteria for separate accounting as a derivative as they are indexed to the Company’s stock. The premiums paid for the 2019 Capped Call Transactions have been included as a net reduction to additional paid-in capital within stockholders’ equity. 2018 Convertible Debt In March 2018, the Company issued the 2018 Notes, $345.0 million aggregate principal amount of 0% Convertible Senior Notes due 2023, in a private placement to qualified institutional buyers pursuant to the Securities Act. The net proceeds from the sale of the 2018 Notes were $335.0 million after deducting the initial purchasers’ discount and offering expenses. The 2018 Notes are convertible based upon an initial conversion rate of 27.5691 shares of the Company’s common stock per $1,000 principal amount of 2018 Notes (equivalent to an initial conversion price of approximately $36.27 per share). The conversion rate will be subject to adjustment upon the occurrence of certain specified events, including certain distributions and dividends to all or substantially all of the holders of the Company’s common stock. The Company will settle any conversions of the 2018 Notes in cash, shares of the Company’s common stock, or a combination thereof, with the form of consideration determined at the Company’s election. The 2018 Notes will mature on March 1, 2023, unless earlier converted or repurchased. Prior to the close of business on the business day immediately preceding November 1, 2022, holders may convert all or a portion of their 2018 Notes only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on June 30, 2018 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the 5 business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of 2018 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; (3) with respect to any or all of the 2018 Notes called for redemption by the Company prior to the close of business on the business day immediately preceding November 1, 2022, holders may convert all or any portion of their 2018 Notes at any time prior to the close of business on the second scheduled trading day prior to the redemption date, even if the 2018 Notes are not otherwise convertible at such time; (4) upon the occurrence of specified corporate events. On and after November 1, 2022 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their Notes at any time, regardless of the foregoing circumstances. If a fundamental change occurs prior to the maturity date, holders may require the Company to repurchase all or a portion of their 2018 Notes for cash at a price equal to 100% of the principal amount of the 2018 Notes to be repurchased. Holders of 2018 Notes who convert their 2018 Notes in connection with a notice of a redemption or a make-whole fundamental change may be entitled to a premium in the form of an increase in the conversion rate of the 2018 Notes. During any calendar quarter preceding November 1, 2022 in which the closing price of the Company’s common stock exceeds 130% of the applicable conversion price of the 2018 Notes on at least 20 of the last 30 consecutive trading days of the quarter, holders may in the immediate quarter following convert all or a portion of their 2018 Notes. Based on the daily closing prices of the Company’s stock during the quarter ended December 31, 2019, holders of the 2018 Notes are not eligible to convert their 2018 Notes during the first quarter of 2020. When a conversion notice is received, the Company has the option to pay or deliver cash, shares of the Company’s common stock, or a combination thereof. Accordingly, the Company cannot be required to settle the 2018 Notes in cash and, therefore, the 2018 Notes are classified as long-term debt as of December 31, 2019. As of December 31, 2019, the if-converted value of the 2018 Notes was approximately $76.4 million higher than the aggregate principal amount, or $421.4 million. The 2018 Notes are general unsecured obligations of the Company. The 2018 Notes rank senior in right of payment to all of the Company’s future indebtedness that is expressly subordinated in right of payment to the Notes; rank equal in right of payment with all of our liabilities that are not so subordinated, including our 2019 Notes; are effectively junior to any of the Company’s secured indebtedness; and are structurally junior to all indebtedness and liabilities (including trade payables) of the Company’s subsidiaries. In accounting for the issuance of the 2018 Notes, the Company separated the 2018 Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component, representing the conversion option, which does not meet the criteria for separate accounting as a derivative as it is indexed to the Company’s own stock, was determined by deducting the fair value of the liability component from the par value of the 2018 Notes. The difference between the principal amount of the 2018 Notes and the liability component represents the debt discount, which is recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheets and accreted over the period from the date of issuance to the contractual maturity date, resulting in the recognition of non-cash interest expense. The equity component of the 2018 Notes of approximately $72.8 million is included in additional paid-in capital in the Consolidated Balance Sheets and is not remeasured as long as it continues to meet the conditions for equity classification. Transaction costs were allocated to the liability and equity components in the same proportion as the allocation of the proceeds. Transaction costs attributable to the liability component were recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheets and are amortized to interest expense using the effective interest method over the term of the 2018 Notes, and transaction costs attributable to the equity component were netted with the equity component in stockholders’ equity. The Company capitalized $10.0 million of debt issuance costs in connection with the 2018 Notes. Non-cash interest expense, including amortization of debt issuance costs, related to the 2018 Notes for the year ended December 31, 2019 and 2018 was $15.2 million and $12.2 million, respectively. Total unamortized debt issuance costs related to the 2018 Notes were $5.2 million and $6.7 million as of December 31, 2019 and 2018, respectively. The estimated fair value of the 2018 Notes was $310.3 million and $279.1 million as of December 31, 2019 and 2018, respectively. The estimated fair value of the 2018 Notes was determined through consideration of quoted market prices for similar instruments. The fair value is classified as Level 2, as defined in “Note 8—Fair Value Measurements.” 2018 Capped Call Transactions The Company used $34.2 million of the net proceeds from the 2018 Notes offering to enter into separate capped call transactions (“2018 Capped Call Transactions”) with the initial purchasers and/or their respective affiliates. The 2018 Capped Call Transactions are expected generally to reduce the potential dilution and/or offset the cash payments the Company is required to make in excess of the principal amount of the 2018 Notes upon conversion of the 2018 Notes in the event that the market price per share of the Company’s common stock is greater than the strike price of the 2018 Capped Call Transactions with such reduction and/or offset subject to a cap. The 2018 Capped Call Transactions have an initial cap price of $52.76 per share of the Company’s common stock, which represents a premium of 100% over the last reported sale price of the Company’s common stock on March 8, 2018, and is subject to certain adjustments under the terms of the 2018 Capped Call Transactions. Collectively, the 2018 Capped Call Transactions cover, initially, the number of shares of the Company’s common stock underlying the 2018 Notes, subject to anti-dilution adjustments substantially similar to those applicable to the 2018 Notes. The Capped Call Transactions do not meet the criteria for separate accounting as a derivative as they are indexed to the Company’s stock. The premiums paid for the 2018 Capped Call Transactions have been included as a net reduction to additional paid-in capital within stockholders’ equity. 2019 Credit Agreement On February 25, 2019, the Company entered into a $200.0 million senior secured revolving credit facility pursuant to a Credit Agreement (the “2019 Credit Agreement”) with lenders party thereto from time to time, and Citibank N.A., as administrative Agent. The 2019 Credit Agreement will mature in February 2024. The 2019 Credit Agreement includes a letter of credit sublimit of $30.0 million and a swingline loan sublimit of $10.0 million. Borrowings under the 2019 Credit Agreement (other than swingline loans) bear interest, at the Company’s option, at (i) a base rate equal to the highest of (a) the prime rate, (b) the federal funds rate plus 0.50%, and (c) an adjusted LIBOR rate for a one-month interest period plus 1.00%, in each case plus a margin ranging from 0.25% to 0.875% or (ii) an adjusted LIBOR rate plus a margin ranging from 1.25% to 1.875%. Swingline loans under the 2019 Credit Agreement bear interest at the same base rate (plus the margin applicable to borrowings bearing interest at the base rate). These margins are determined based on the senior secured net leverage ratio (defined as secured funded debt, net of unrestricted cash up to $100 million, to EBITDA) for the preceding four fiscal quarter period. The Company is also obligated to pay other customary fees for a credit facility of this size and type, including an unused commitment fee, ranging from 0.20% to 0.35% depending on the Company’s senior secured net leverage ratio, and fees associated with letters of credit. The 2019 Credit Agreement also permits the Company, in certain circumstances, to request an increase in the facility by an amount of up to $100.0 million at the same maturity, pricing and other terms and to request an extension of the maturity date for the facility. In connection with the 2019 Credit Agreement, the Company also paid the lenders certain upfront fees. The 2019 Credit Agreement contains customary representations and warranties applicable to the Company and its subsidiaries and customary affirmative and negative covenants applicable to the Company and its restricted subsidiaries. The negative covenants include restrictions on, among other things, indebtedness, liens, certain fundamental changes (including mergers), investments, dispositions, restricted payments (including dividends and stock repurchases), prepayments of junior debt, and transactions with affiliates. These restrictions do not prohibit a subsidiary of the Company from making pro rata payments to the Company or any other person that owns an equity interest in such subsidiary. The 2019 Credit Agreement contains financial covenants, that require the Company and its subsidiaries to maintain (i) a secured net leverage ratio not to exceed 3.00 to 1.00, subject to an increase, at the option of the Company, to 3.50 to 1.00 for a specified period of time in the event of certain material acquisitions, tested as of the last day of each fiscal quarter and (ii) an interest coverage ratio (defined as the ratio of EBITDA to cash interest expense) of not less than 2.50 to 1.00, tested for each fiscal quarter. The 2019 Credit Agreement includes customary events of default, including, but not limited to, nonpayment of principal or interest, breaches of representations and warranties, failure to perform or observe covenants, cross-defaults with certain other indebtedness, final judgments or orders, certain change of control events, and certain bankruptcy-related events or proceedings. Upon the occurrence of an event of default (subject to notice and grace periods), obligations under the 2019 Credit Agreement could be accelerated. Subject to certain exceptions, to the extent the Company has any material domestic subsidiaries, the obligations under the 2019 Credit Agreement would be required to be guaranteed by such material domestic subsidiaries. The obligations under the 2019 Credit Agreement are secured by all or substantially all of the assets of the Company and any such subsidiary guarantors. The Company capitalized $1.4 million of debt issuance costs in connection with the 2019 Credit Agreement. Non-cash interest expense related to debt issuance costs on the 2019 Credit Agreement for the year ended December 31, 2019 was $0.3 million. Total unamortized debt issuance costs related to the 2019 Credit Agreement were $1.1 million as of December 31, 2019. At December 31, 2019, the Company did not have any borrowings under the 2019 Credit Agreement and was in compliance with all financial covenants.

In September 2019, the Company issued $650.0 million aggregate principal amount of 0.125% Convertible Senior Notes due 2026 (the “2019 Notes”) in a private placement to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”). The net proceeds from the sale of the 2019 Notes were $639.5 million after deducting the initial purchasers’ discount and offering expenses.

The 2019 Notes are convertible based upon an initial conversion rate of 11.4040 shares of the Company’s common stock per $1,000 principal amount of 2019 Notes (equivalent to an initial conversion price of approximately $87.69 per share). The conversion rate will be subject to adjustment upon the occurrence of certain specified events, including certain distributions and dividends to all or substantially all of the holders of the Company’s common stock. The Company will settle any conversions of the 2019 Notes in cash, shares of the Company’s common stock, or a combination thereof, with the form of consideration determined at the Company’s election.

The 2019 Notes will mature on October 1, 2026, unless earlier converted or repurchased. Prior to the close of business on the business day immediately preceding June 1, 2026, holders may convert all or a portion of their 2019 Notes only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on December 31, 2019 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the 5 business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of 2019 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; (3) with respect to any or all of the 2019 Notes called for redemption by the Company prior to the close of business on the business day immediately preceding June 1, 2026, holders may convert all or any portion of their 2019 Notes at any time prior to the close of business on the second scheduled trading day prior to the redemption date, even if the 2019 Notes are not otherwise convertible at such time; and (4) upon the occurrence of specified corporate events. On and after June 1, 2026 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their 2019 Notes at any time, regardless of the foregoing circumstances. As of December 31, 2019, the if-converted value of the 2019 Notes was approximately $321.6 million lower than the aggregate principal amount, or $328.4 million.

If a fundamental change occurs prior to the maturity date, holders may require the Company to repurchase all or a portion of their 2019 Notes for cash at a price equal to 100% of the principal amount of the 2019 Notes to be repurchased. Holders of 2019 Notes who convert their 2019 Notes in connection with a notice of a redemption or a make-whole fundamental change may be entitled to a premium in the form of an increase in the conversion rate of the 2019 Notes. As of December 31, 2019, none of the conditions permitting the holders of the 2019 Notes to early convert have been met.

In accounting for the issuance of the 2019 Notes, the Company separated the 2019 Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component, representing the conversion option, which does not meet the criteria for separate accounting as a derivative as it is indexed to the Company’s own stock, was determined by deducting the fair value of the liability component from the par value of the 2019 Notes. The difference between the principal amount of the 2019 Notes and the liability component represents the debt discount, which is recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheet and accreted over the period from the date of issuance to the contractual maturity date, resulting in the recognition of non-cash interest expense. The equity component of the 2019 Notes of approximately $154.0 million is included in additional paid-in capital in the Consolidated Balance Sheet and is not remeasured as long as it continues to meet the conditions for equity classification. Transaction costs were allocated to the liability and equity components in the same proportion as the allocation of the proceeds. Transaction costs attributable to the liability component were recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheet and are amortized to interest expense using the effective interest method over the term of the 2019 Notes, and transaction costs attributable to the equity component were netted with the equity component in stockholders’ equity.

The Company used $76.2 million of the net proceeds from the 2019 Notes offering to enter into separate capped call transactions (“2019 Capped Call Transactions”) with the initial purchasers and/or their respective affiliates. The 2019 Capped Call Transactions are expected generally to reduce the potential dilution and/or offset the cash payments the Company is required to make in excess of the principal amount of the 2019 Notes upon conversion of the 2019 Notes in the event that the market price per share of the Company’s common stock is greater than the strike price of the 2019 Capped Call Transactions with such reduction and/or offset subject to a cap. The 2019 Capped Call Transactions have an initial cap price of $148.63 per share of the Company’s common stock, which represents a premium of 150% over the last reported sale price of the Company’s common stock on September 18, 2019, and is subject to certain adjustments under the terms of the 2019 Capped Call Transactions. Collectively, the 2019 Capped Call Transactions cover, initially, the number of shares of the Company’s common stock underlying the 2019 Notes, subject to anti-dilution adjustments substantially similar to those applicable to the 2019 Notes.

The 2018 Notes are convertible based upon an initial conversion rate of 27.5691 shares of the Company’s common stock per $1,000 principal amount of 2018 Notes (equivalent to an initial conversion price of approximately $36.27 per share). The conversion rate will be subject to adjustment upon the occurrence of certain specified events, including certain distributions and dividends to all or substantially all of the holders of the Company’s common stock. The Company will settle any conversions of the 2018 Notes in cash, shares of the Company’s common stock, or a combination thereof, with the form of consideration determined at the Company’s election.

The 2018 Notes will mature on March 1, 2023, unless earlier converted or repurchased. Prior to the close of business on the business day immediately preceding November 1, 2022, holders may convert all or a portion of their 2018 Notes only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on June 30, 2018 (and only during such calendar quarter), if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the 5 business day period after any 10 consecutive trading day period (the “measurement period”) in which the trading price per $1,000 principal amount of 2018 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company’s common stock and the conversion rate on each such trading day; (3) with respect to any or all of the 2018 Notes called for redemption by the Company prior to the close of business on the business day immediately preceding November 1, 2022, holders may convert all or any portion of their 2018 Notes at any time prior to the close of business on the second scheduled trading day prior to the redemption date, even if the 2018 Notes are not otherwise convertible at such time; (4) upon the occurrence of specified corporate events. On and after November 1, 2022 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their Notes at any time, regardless of the foregoing circumstances.

If a fundamental change occurs prior to the maturity date, holders may require the Company to repurchase all or a portion of their 2018 Notes for cash at a price equal to 100% of the principal amount of the 2018 Notes to be repurchased. Holders of 2018 Notes who convert their 2018 Notes in connection with a notice of a redemption or a make-whole fundamental change may be entitled to a premium in the form of an increase in the conversion rate of the 2018 Notes.

During any calendar quarter preceding November 1, 2022 in which the closing price of the Company’s common stock exceeds 130% of the applicable conversion price of the 2018 Notes on at least 20 of the last 30 consecutive trading days of the quarter, holders may in the immediate quarter following convert all or a portion of their 2018 Notes. Based on the daily closing prices of the Company’s stock during the quarter ended December 31, 2019, holders of the 2018 Notes are not eligible to convert their 2018 Notes during the first quarter of 2020. When a conversion notice is received, the Company has the option to pay or deliver cash, shares of the Company’s common stock, or a combination thereof. Accordingly, the Company cannot be required to settle the 2018 Notes in cash and, therefore, the 2018 Notes are classified as long-term debt as of December 31, 2019. As of December 31, 2019, the if-converted value of the 2018 Notes was approximately $76.4 million higher than the aggregate principal amount, or $421.4 million.

The 2018 Notes are general unsecured obligations of the Company. The 2018 Notes rank senior in right of payment to all of the Company’s future indebtedness that is expressly subordinated in right of payment to the Notes; rank equal in right of payment with all of our liabilities that are not so subordinated, including our 2019 Notes; are effectively junior to any of the Company’s secured indebtedness; and are structurally junior to all indebtedness and liabilities (including trade payables) of the Company’s subsidiaries.

In accounting for the issuance of the 2018 Notes, the Company separated the 2018 Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar liability that does not have an associated convertible feature. The carrying amount of the equity component, representing the conversion option, which does not meet the criteria for separate accounting as a derivative as it is indexed to the Company’s own stock, was determined by deducting the fair value of the liability component from the par value of the 2018 Notes. The difference between the principal amount of the 2018 Notes and the liability component represents the debt discount, which is recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheets and accreted over the period from the date of issuance to the contractual maturity date, resulting in the recognition of non-cash interest expense. The equity component of the 2018 Notes of approximately $72.8 million is included in additional paid-in capital in the Consolidated Balance Sheets and is not remeasured as long as it continues to meet the conditions for equity classification. Transaction costs were allocated to the liability and equity components in the same proportion as the allocation of the proceeds. Transaction costs attributable to the liability component were recorded as a direct deduction from the related debt liability in the Consolidated Balance Sheets and are amortized to interest expense using the effective interest method over the term of the 2018 Notes, and transaction costs attributable to the equity component were netted with the equity component in stockholders’ equity.

The Company capitalized $10.0 million of debt issuance costs in connection with the 2018 Notes. Non-cash interest expense, including amortization of debt issuance costs, related to the 2018 Notes for the year ended December 31, 2019 and 2018 was $15.2 million and $12.2 million, respectively. Total unamortized debt issuance costs related to the 2018 Notes were $5.2 million and $6.7 million as of December 31, 2019 and 2018, respectively.

The Company used $34.2 million of the net proceeds from the 2018 Notes offering to enter into separate capped call transactions (“2018 Capped Call Transactions”) with the initial purchasers and/or their respective affiliates. The 2018 Capped Call Transactions are expected generally to reduce the potential dilution and/or offset the cash payments the Company is required to make in excess of the principal amount of the 2018 Notes upon conversion of the 2018 Notes in the event that the market price per share of the Company’s common stock is greater than the strike price of the 2018 Capped Call Transactions with such reduction and/or offset subject to a cap. The 2018 Capped Call Transactions have an initial cap price of $52.76 per share of the Company’s common stock, which represents a premium of 100% over the last reported sale price of the Company’s common stock on March 8, 2018, and is subject to certain adjustments under the terms of the 2018 Capped Call Transactions. Collectively, the 2018 Capped Call Transactions cover, initially, the number of shares of the Company’s common stock underlying the 2018 Notes, subject to anti-dilution adjustments substantially similar to those applicable to the 2018 Notes.

On February 25, 2019, the Company entered into a $200.0 million senior secured revolving credit facility pursuant to a Credit Agreement (the “2019 Credit Agreement”) with lenders party thereto from time to time, and Citibank N.A., as administrative Agent. The 2019 Credit Agreement will mature in February 2024. The 2019 Credit Agreement includes a letter of credit sublimit of $30.0 million and a swingline loan sublimit of $10.0 million.

Borrowings under the 2019 Credit Agreement (other than swingline loans) bear interest, at the Company’s option, at (i) a base rate equal to the highest of (a) the prime rate, (b) the federal funds rate plus 0.50%, and (c) an adjusted LIBOR rate for a one-month interest period plus 1.00%, in each case plus a margin ranging from 0.25% to 0.875% or (ii) an adjusted LIBOR rate plus a margin ranging from 1.25% to 1.875%. Swingline loans under the 2019 Credit Agreement bear interest at the same base rate (plus the margin applicable to borrowings bearing interest at the base rate). These margins are determined based on the senior secured net leverage ratio (defined as secured funded debt, net of unrestricted cash up to $100 million, to EBITDA) for the preceding four fiscal quarter period. The Company is also obligated to pay other customary fees for a credit facility of this size and type, including an unused commitment fee, ranging from 0.20% to 0.35% depending on the Company’s senior secured net leverage ratio, and fees associated with letters of credit. The 2019 Credit Agreement also permits the Company, in certain circumstances, to request an increase in the facility by an amount of up to $100.0 million at the same maturity, pricing and other terms and to request an extension of the maturity date for the facility. In connection with the 2019 Credit Agreement, the Company also paid the lenders certain upfront fees.

The 2019 Credit Agreement contains customary representations and warranties applicable to the Company and its subsidiaries and customary affirmative and negative covenants applicable to the Company and its restricted subsidiaries. The negative covenants include restrictions on, among other things, indebtedness, liens, certain fundamental changes (including mergers), investments, dispositions, restricted payments (including dividends and stock repurchases), prepayments of junior debt, and transactions with affiliates. These restrictions do not prohibit a subsidiary of the Company from making pro rata payments to the Company or any other person that owns an equity interest in such subsidiary. The 2019 Credit Agreement contains financial covenants, that require the Company and its subsidiaries to maintain (i) a secured net leverage ratio not to exceed 3.00 to 1.00, subject to an increase, at the option of the Company, to 3.50 to 1.00 for a specified period of time in the event of certain material acquisitions, tested as of the last day of each fiscal quarter and (ii) an interest coverage ratio (defined as the ratio of EBITDA to cash interest expense) of not less than 2.50 to 1.00, tested for each fiscal quarter.

The 2019 Credit Agreement includes customary events of default, including, but not limited to, nonpayment of principal or interest, breaches of representations and warranties, failure to perform or observe covenants, cross-defaults with certain other indebtedness, final judgments or orders, certain change of control events, and certain bankruptcy-related events or proceedings. Upon the occurrence of an event of default (subject to notice and grace periods), obligations under the 2019 Credit Agreement could be accelerated.