Convertible and Long-term Debt Obligations	3 Months Ended
Mar. 31, 2014
Debt Disclosure [Abstract]
Convertible and Long-term Debt Obligations	6. Convertible and Long-term Debt Obligations *0.25% and 1.25% Convertible Senior Notes and Bond Hedge and Warrant Transactions* In March 2014, we issued $800.0 million principal amount of 0.25% convertible senior notes due 2019 (2019 Notes) and $1.20 billion principal amount of 1.25% convertible senior notes due 2021 (2021 Notes) in a public offering. The net proceeds from the offering, after deducting transaction costs, were approximately $787.6 million from the 2019 Notes and $1.18 billion from the 2021 Notes, respectively. We incurred $12.4 million and $18.7 million, respectively, of debt issuance costs in connection with the 2019 Notes and the 2021 Notes, which we initially recorded in other assets and are amortizing to interest expense using the effective interest method over the contractual terms of these notes. The interest rates are fixed at 0.25% and 1.25% per annum and are payable semi-annually in arrears on March 1 and September 1 of each year, commencing on September 1, 2014. During the three months ended March 31, 2014, we recognized $0.2 million of interest expense related to the amortization of debt issuance costs and $1.2 million of accrued coupon interest expense. Each $1,000 of principal of these notes will initially be convertible into 2.7788 shares of our common stock, which is equivalent to an initial conversion price of approximately $359.87 per share, subject to adjustment upon the occurrence of specified events. Holders of these notes may convert their Notes at their option on or after December 1, 2018 for the 2019 Notes and on or after December 1, 2020 for the 2021 Notes. Further, holders of these notes may convert their notes at their option prior to the respective dates above, only under the following circumstances: (1) during any fiscal quarter beginning after the fiscal quarter ending June 30, 2014, if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during the last 30 consecutive trading days of the immediately preceding fiscal quarter is greater than or equal to 130% of the conversion price of the applicable notes on each applicable trading day; (2) during the five business day period following any five consecutive trading day period in which the trading price for the applicable notes is less than 98% of the average of the closing sale price of our common stock for each day during such five trading day period; or (3) if we make specified distributions to holders of our common stock or if specified corporate transactions occur. Upon conversion of the 2019 Notes, we would pay or deliver as applicable, cash, shares of our common stock or a combination of cash and shares of our common stock, at our election. Upon conversion of the 2021 Notes, we would pay the holders in cash for the principal amount and, if applicable, shares of our common stock (subject to our right to deliver cash in lieu of all or a portion of such shares of our common stock) based on a daily conversion value. If a fundamental change occurs prior to the maturity date, holders of these notes may require us to repurchase all or a portion of their notes for cash at a repurchase price equal to 100% of the principal amount of the notes, plus any accrued and unpaid interest. In addition, if specific corporate events occur prior to the applicable maturity date, we will increase the conversion rate for a holder who elects to convert their notes in connection with such a corporate event in certain circumstances. In accordance with accounting guidance on embedded conversion features, we valued and bifurcated the conversion option associated with the Notes from the respective host debt instrument and initially recorded the conversion option of $163.6 million for the 2019 Notes and $321.2 million for the 2021 Notes in stockholders’ equity. The resulting debt discounts on the 2019 Notes and 2021 Notes are being amortized to interest expense at an effective interest rate of 4.89% and 5.96%, respectively, over the contractual terms of the Notes. During the three months ended March 31, 2014, we recognized $4.7 million of interest expense related to the amortization of the debt discount. As of March 31, 2014, the net carrying value of the 2019 Notes and the 2021 Notes was $638.5 million and $881.5 million, respectively. In connection with the offering of these notes, we entered into convertible note hedge transactions whereby we have the option to purchase (subject to adjustment for certain specified events) a total of approximately 5.6 million shares of our common stock at a price of approximately $359.87 per share. The total cost of the convertible note hedge transactions was $524.7 million. In addition, we sold warrants whereby the holders of the warrants have the option to purchase (subject to adjustment for certain specified events) a total of approximately 2.2 million shares of our common stock at a price of $512.66 for the 2019 Notes and a total of approximately 3.3 million shares of our common stock at a price of $560.64 per share for the 2021 Notes. We received $338.4 million in cash proceeds from the sale of these warrants. Taken together, the purchase of the convertible note hedges and the sale of warrants are intended to offset any actual dilution from the conversion of these notes and to effectively increase the overall conversion price from $359.87 to $512.66 per share in the case of warrants relating to the 2019 Notes and from $359.87 to $560.64 in the case of warrants relating to the 2021 Notes. As these transactions meet certain accounting criteria, the convertible note hedges and warrants are recorded in stockholders’ equity and are not accounted for as derivatives. The net cost incurred in connection with the convertible note hedge and warrant transactions was recorded as a reduction to additional paid-in capital in the condensed consolidated balance sheet as of March 31, 2014. *1.50% Convertible Senior Notes and Bond Hedge and Warrant Transactions* In May 2013, we issued $660.0 million aggregate principal amount of convertible senior notes due 2018 (2018 Notes) in a public offering. The net proceeds from the offering, after deducting transaction costs, were approximately $648.0 million. We incurred $12.0 million of debt issuance costs in connection with the 2018 Notes which we initially recorded in other assets and are amortizing to interest expense using the effective interest method over the contractual term of the 2018 Notes. The interest under the 2018 Notes is fixed at 1.50% per annum and is payable semi-annually in arrears on June 1 and December 1 of each year, commencing on December 1, 2013. During the three months ended March 31, 2014, we recognized $0.5 million of interest expense related to the amortization of debt issuance costs and $2.4 million of accrued coupon interest expense. Each $1,000 of principal of the 2018 Notes will initially be convertible into 8.0306 shares of our common stock, which is equivalent to an initial conversion price of approximately $124.52 per share, subject to adjustment upon the occurrence of specified events. Holders of the 2018 Notes may convert their notes at their option on or after March 1, 2018. Further, holders of the 2018 Notes may convert their notes at their option prior to March 1, 2018, only under the following circumstances: (1) during any fiscal quarter beginning after the fiscal quarter ending September 30, 2013, if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during the last 30 consecutive trading days of the immediately preceding fiscal quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the five business day period following any five consecutive trading day period in which the trading price for the 2018 Notes is less than 98% of the average of the closing sale price of our common stock for each day during such five trading day period; or (3) if we make specified distributions to holders of our common stock or if specified corporate transactions occur. Upon conversion, we would pay the holders in cash for the principal amount of the 2018 Notes and, if applicable, shares of our common stock (subject to our right to deliver cash in lieu of all or a portion of such shares of our common stock) based on a daily conversion value. If a fundamental change occurs prior to the maturity date, holders of the 2018 Notes may require us to repurchase all or a portion of their notes for cash at a repurchase price equal to 100% of the principal amount of the notes, plus any accrued and unpaid interest. In addition, if specific corporate events occur prior to the maturity date, we will increase the conversion rate for a holder who elects to convert their notes in connection with such a corporate event in certain circumstances. In accordance with accounting guidance on embedded conversion features, we valued and bifurcated the conversion option associated with the 2018 Notes from the host debt instrument and initially recorded the conversion option of $82.8 million in stockholders’ equity. The resulting debt discount on the 2018 Notes is being amortized to interest expense at an effective interest rate of 4.29% over the contractual term of the notes. During the three months ended March 31, 2014, we recognized $3.8 million of interest expense related to the amortization of the debt discount. As of March 31, 2014, the net carrying value of the 2018 Notes was $589.9 million. In connection with the offering of the 2018 Notes, we entered into convertible note hedge transactions whereby we have the option to purchase (subject to adjustment for certain specified events) a total of approximately 5.3 million shares of our common stock at a price of approximately $124.52 per share. The cost of the convertible note hedge transactions was $177.5 million. In addition, we sold warrants whereby the holders of the warrants have the option to purchase (subject to adjustment for certain specified events) a total of approximately 5.3 million shares of our common stock at a price of $184.48 per share. We received $120.3 million in cash proceeds from the sale of these warrants. Taken together, the purchase of the convertible note hedges and the sale of warrants are intended to offset any actual dilution from the conversion of the 2018 Notes and to effectively increase the overall conversion price from $124.52 to $184.48 per share. As these transactions meet certain accounting criteria, the convertible note hedges and warrants are recorded in stockholders’ equity and are not accounted for as derivatives. The net cost incurred in connection with the convertible note hedge and warrant transactions was recorded as a reduction to additional paid-in capital in the condensed consolidated balance sheet. During the first quarter of 2014, the closing price of our common stock exceeded 130% of the applicable conversion price of our 2018 Notes on at least 20 of the last 30 consecutive trading days of the quarter; therefore, holders of the 2018 Notes may convert their notes during the second quarter of 2014. As such, we reclassified the $589.9 million carrying value of our 2018 Notes to current liabilities and reclassified $69.9 million, representing the difference between the aggregate principal of our 2018 Notes of $659.8 million and the carrying value of the 2018 Notes, from additional paid-in capital to mezzanine equity on our condensed consolidated balance sheet as of March 31, 2014. Similarly, debt issuance costs previously recorded in other assets were reclassified to other current assets as of March 31, 2014. Should the closing price conditions be met in the second quarter of 2014 or a future quarter, the 2018 Notes will be convertible at their holders’ option during the immediately following quarters. *Full Repayment of DOE Loan Facility and Expiration of DOE Warrant* On January 20, 2010, we entered into a loan facility with the Federal Financing Bank (FFB), and the Department of Energy (DOE), pursuant to the Advanced Technology Vehicles Manufacturing Incentive Program. We refer to the loan facility with the DOE as the DOE Loan Facility. Under the DOE Loan Facility, the FFB had made available to us two multi-draw term loan facilities in an aggregate principal amount of $465.0 million. As of August 31, 2012, we had fully drawn down the aforementioned facilities. In connection with the closing of the DOE Loan Facility, we issued in January 2010 a warrant to the DOE to purchase up to 9,255,035 shares of our Series E convertible preferred stock at an exercise price of $2.51 per share. Upon the completion of our initial public offering on July 2, 2010, this preferred stock warrant became a warrant to purchase up to 3,090,111 shares of common stock at an exercise price of $7.54 per share. In March 2013, we entered into an amendment with the DOE under which we agreed to repay all outstanding principal and interest payments under the DOE Loan Facility by December 15, 2017 prior to the warrant vesting start date of December 15, 2018; therefore, the DOE warrant was no longer expected to vest and its fair value was reduced to zero as of March 31, 2013. During the three months ended March 31, 2013, we recognized other income for the reduction of the fair value of the DOE warrant in the amount of $10.7 million. In May 2013, in connection with the closing of our offerings of common stock and 2018 Notes, we paid $451.8 million to settle all outstanding loan amounts of $441.0 million under the DOE Loan Facility, including principal and interest, as well as an early repayment penalty of $10.8 million which was recorded in interest expense for the year ended December 31, 2013. Upon termination of the DOE Loan Facility, $29.3 million previously held in a dedicated debt service account was released by the DOE.

6. Convertible and Long-term Debt Obligations

0.25% and 1.25% Convertible Senior Notes and Bond Hedge and Warrant Transactions

In March 2014, we issued $800.0 million principal amount of 0.25% convertible senior notes due 2019 (2019 Notes) and $1.20 billion principal amount of 1.25% convertible senior notes due 2021 (2021 Notes) in a public offering. The net proceeds from the offering, after deducting transaction costs, were approximately $787.6 million from the 2019 Notes and $1.18 billion from the 2021 Notes, respectively. We incurred $12.4 million and $18.7 million, respectively, of debt issuance costs in connection with the 2019 Notes and the 2021 Notes, which we initially recorded in other assets and are amortizing to interest expense using the effective interest method over the contractual terms of these notes. The interest rates are fixed at 0.25% and 1.25% per annum and are payable semi-annually in arrears on March 1 and September 1 of each year, commencing on September 1, 2014. During the three months ended March 31, 2014, we recognized $0.2 million of interest expense related to the amortization of debt issuance costs and $1.2 million of accrued coupon interest expense.

Each $1,000 of principal of these notes will initially be convertible into 2.7788 shares of our common stock, which is equivalent to an initial conversion price of approximately $359.87 per share, subject to adjustment upon the occurrence of specified events. Holders of these notes may convert their Notes at their option on or after December 1, 2018 for the 2019 Notes and on or after December 1, 2020 for the 2021 Notes. Further, holders of these notes may convert their notes at their option prior to the respective dates above, only under the following circumstances: (1) during any fiscal quarter beginning after the fiscal quarter ending June 30, 2014, if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during the last 30 consecutive trading days of the immediately preceding fiscal quarter is greater than or equal to 130% of the conversion price of the applicable notes on each applicable trading day; (2) during the five business day period following any five consecutive trading day period in which the trading price for the applicable notes is less than 98% of the average of the closing sale price of our common stock for each day during such five trading day period; or (3) if we make specified distributions to holders of our common stock or if specified corporate transactions occur. Upon conversion of the 2019 Notes, we would pay or deliver as applicable, cash, shares of our common stock or a combination of cash and shares of our common stock, at our election. Upon conversion of the 2021 Notes, we would pay the holders in cash for the principal amount and, if applicable, shares of our common stock (subject to our right to deliver cash in lieu of all or a portion of such shares of our common stock) based on a daily conversion value. If a fundamental change occurs prior to the maturity date, holders of these notes may require us to repurchase all or a portion of their notes for cash at a repurchase price equal to 100% of the principal amount of the notes, plus any accrued and unpaid interest. In addition, if specific corporate events occur prior to the applicable maturity date, we will increase the conversion rate for a holder who elects to convert their notes in connection with such a corporate event in certain circumstances.

In accordance with accounting guidance on embedded conversion features, we valued and bifurcated the conversion option associated with the Notes from the respective host debt instrument and initially recorded the conversion option of $163.6 million for the 2019 Notes and $321.2 million for the 2021 Notes in stockholders’ equity. The resulting debt discounts on the 2019 Notes and 2021 Notes are being amortized to interest expense at an effective interest rate of 4.89% and 5.96%, respectively, over the contractual terms of the Notes. During the three months ended March 31, 2014, we recognized $4.7 million of interest expense related to the amortization of the debt discount. As of March 31, 2014, the net carrying value of the 2019 Notes and the 2021 Notes was $638.5 million and $881.5 million, respectively.

In connection with the offering of these notes, we entered into convertible note hedge transactions whereby we have the option to purchase (subject to adjustment for certain specified events) a total of approximately 5.6 million shares of our common stock at a price of approximately $359.87 per share. The total cost of the convertible note hedge transactions was $524.7 million. In addition, we sold warrants whereby the holders of the warrants have the option to purchase (subject to adjustment for certain specified events) a total of approximately 2.2 million shares of our common stock at a price of $512.66 for the 2019 Notes and a total of approximately 3.3 million shares of our common stock at a price of $560.64 per share for the 2021 Notes. We received $338.4 million in cash proceeds from the sale of these warrants. Taken together, the purchase of the convertible note hedges and the sale of warrants are intended to offset any actual dilution from the conversion of these notes and to effectively increase the overall conversion price from $359.87 to $512.66 per share in the case of warrants relating to the 2019 Notes and from $359.87 to $560.64 in the case of warrants relating to the 2021 Notes. As these transactions meet certain accounting criteria, the convertible note hedges and warrants are recorded in stockholders’ equity and are not accounted for as derivatives. The net cost incurred in connection with the convertible note hedge and warrant transactions was recorded as a reduction to additional paid-in capital in the condensed consolidated balance sheet as of March 31, 2014.

1.50% Convertible Senior Notes and Bond Hedge and Warrant Transactions

In May 2013, we issued $660.0 million aggregate principal amount of convertible senior notes due 2018 (2018 Notes) in a public offering. The net proceeds from the offering, after deducting transaction costs, were approximately $648.0 million. We incurred $12.0 million of debt issuance costs in connection with the 2018 Notes which we initially recorded in other assets and are amortizing to interest expense using the effective interest method over the contractual term of the 2018 Notes. The interest under the 2018 Notes is fixed at 1.50% per annum and is payable semi-annually in arrears on June 1 and December 1 of each year, commencing on December 1, 2013. During the three months ended March 31, 2014, we recognized $0.5 million of interest expense related to the amortization of debt issuance costs and $2.4 million of accrued coupon interest expense.

Each $1,000 of principal of the 2018 Notes will initially be convertible into 8.0306 shares of our common stock, which is equivalent to an initial conversion price of approximately $124.52 per share, subject to adjustment upon the occurrence of specified events. Holders of the 2018 Notes may convert their notes at their option on or after March 1, 2018. Further, holders of the 2018 Notes may convert their notes at their option prior to March 1, 2018, only under the following circumstances: (1) during any fiscal quarter beginning after the fiscal quarter ending September 30, 2013, if the last reported sale price of our common stock for at least 20 trading days (whether or not consecutive) during the last 30 consecutive trading days of the immediately preceding fiscal quarter is greater than or equal to 130% of the conversion price on each applicable trading day; (2) during the five business day period following any five consecutive trading day period in which the trading price for the 2018 Notes is less than 98% of the average of the closing sale price of our common stock for each day during such five trading day period; or (3) if we make specified distributions to holders of our common stock or if specified corporate transactions occur. Upon conversion, we would pay the holders in cash for the principal amount of the 2018 Notes and, if applicable, shares of our common stock (subject to our right to deliver cash in lieu of all or a portion of such shares of our common stock) based on a daily conversion value. If a fundamental change occurs prior to the maturity date, holders of the 2018 Notes may require us to repurchase all or a portion of their notes for cash at a repurchase price equal to 100% of the principal amount of the notes, plus any accrued and unpaid interest. In addition, if specific corporate events occur prior to the maturity date, we will increase the conversion rate for a holder who elects to convert their notes in connection with such a corporate event in certain circumstances.

In accordance with accounting guidance on embedded conversion features, we valued and bifurcated the conversion option associated with the 2018 Notes from the host debt instrument and initially recorded the conversion option of $82.8 million in stockholders’ equity. The resulting debt discount on the 2018 Notes is being amortized to interest expense at an effective interest rate of 4.29% over the contractual term of the notes. During the three months ended March 31, 2014, we recognized $3.8 million of interest expense related to the amortization of the debt discount. As of March 31, 2014, the net carrying value of the 2018 Notes was $589.9 million.

In connection with the offering of the 2018 Notes, we entered into convertible note hedge transactions whereby we have the option to purchase (subject to adjustment for certain specified events) a total of approximately 5.3 million shares of our common stock at a price of approximately $124.52 per share. The cost of the convertible note hedge transactions was $177.5 million. In addition, we sold warrants whereby the holders of the warrants have the option to purchase (subject to adjustment for certain specified events) a total of approximately 5.3 million shares of our common stock at a price of $184.48 per share. We received $120.3 million in cash proceeds from the sale of these warrants. Taken together, the purchase of the convertible note hedges and the sale of warrants are intended to offset any actual dilution from the conversion of the 2018 Notes and to effectively increase the overall conversion price from $124.52 to $184.48 per share. As these transactions meet certain accounting criteria, the convertible note hedges and warrants are recorded in stockholders’ equity and are not accounted for as derivatives. The net cost incurred in connection with the convertible note hedge and warrant transactions was recorded as a reduction to additional paid-in capital in the condensed consolidated balance sheet.

During the first quarter of 2014, the closing price of our common stock exceeded 130% of the applicable conversion price of our 2018 Notes on at least 20 of the last 30 consecutive trading days of the quarter; therefore, holders of the 2018 Notes may convert their notes during the second quarter of 2014. As such, we reclassified the $589.9 million carrying value of our 2018 Notes to current liabilities and reclassified $69.9 million, representing the difference between the aggregate principal of our 2018 Notes of $659.8 million and the carrying value of the 2018 Notes, from additional paid-in capital to mezzanine equity on our condensed consolidated balance sheet as of March 31, 2014. Similarly, debt issuance costs previously recorded in other assets were reclassified to other current assets as of March 31, 2014. Should the closing price conditions be met in the second quarter of 2014 or a future quarter, the 2018 Notes will be convertible at their holders’ option during the immediately following quarters.

Full Repayment of DOE Loan Facility and Expiration of DOE Warrant

On January 20, 2010, we entered into a loan facility with the Federal Financing Bank (FFB), and the Department of Energy (DOE), pursuant to the Advanced Technology Vehicles Manufacturing Incentive Program. We refer to the loan facility with the DOE as the DOE Loan Facility. Under the DOE Loan Facility, the FFB had made available to us two multi-draw term loan facilities in an aggregate principal amount of $465.0 million. As of August 31, 2012, we had fully drawn down the aforementioned facilities.

In connection with the closing of the DOE Loan Facility, we issued in January 2010 a warrant to the DOE to purchase up to 9,255,035 shares of our Series E convertible preferred stock at an exercise price of $2.51 per share. Upon the completion of our initial public offering on July 2, 2010, this preferred stock warrant became a warrant to purchase up to 3,090,111 shares of common stock at an exercise price of $7.54 per share.

In March 2013, we entered into an amendment with the DOE under which we agreed to repay all outstanding principal and interest payments under the DOE Loan Facility by December 15, 2017 prior to the warrant vesting start date of December 15, 2018; therefore, the DOE warrant was no longer expected to vest and its fair value was reduced to zero as of March 31, 2013. During the three months ended March 31, 2013, we recognized other income for the reduction of the fair value of the DOE warrant in the amount of $10.7 million.

In May 2013, in connection with the closing of our offerings of common stock and 2018 Notes, we paid $451.8 million to settle all outstanding loan amounts of $441.0 million under the DOE Loan Facility, including principal and interest, as well as an early repayment penalty of $10.8 million which was recorded in interest expense for the year ended December 31, 2013. Upon termination of the DOE Loan Facility, $29.3 million previously held in a dedicated debt service account was released by the DOE.