Long Term Obligations	12 Months Ended
Dec. 31, 2014
Debt Disclosure [Abstract]
Long Term Obligations	Long Term Obligations Fan Pier Leases In 2011, the Company entered into two lease agreements, pursuant to which the Company leases approximately 1.1 million square feet of office and laboratory space in two buildings (the “Buildings”) at Fan Pier in Boston, Massachusetts (the “Fan Pier Leases”). The Company commenced lease payments in December 2013, and will make lease payments pursuant to the Fan Pier Leases through December 2028. The Company has an option to extend the term of the Fan Pier Leases for an additional 10 years. Because the Company was involved in the construction project, the Company was deemed for accounting purposes to be the owner of the Buildings during the construction period and recorded project construction costs incurred by the landlord. Upon completion of the Buildings, the Company evaluated the Fan Pier Leases and determined that the Fan Pier Leases did not meet the criteria for “sale-leaseback” treatment. Accordingly, the Company began depreciating the asset and incurring interest expense related to the financing obligation in 2013. The Company bifurcates its lease payments pursuant to the Fan Pier Leases into (i) a portion that is allocated to the Buildings and (ii) a portion that is allocated to the land on which the Buildings were constructed. The portion of the lease obligations allocated to the land is treated as an operating lease that commenced in 2011. In 2014, the Company recorded $60.2 million in interest expense, $13.4 million in depreciation expense and $6.5 million in rent expense related to the Buildings. Property and equipment, net, included $515.0 million and $503.4 million as of December 31, 2014 and 2013, respectively, related to construction costs for the Buildings. The carrying value of the construction financing lease obligation related to the Buildings, which excludes interest that will be imputed over the course of the Company’s lease agreement for the Buildings, was $473.4 million and $440.9 million, as of December 31, 2014 and 2013, respectively. Term Loan On July 9, 2014, the Company entered into a credit agreement with the lenders party thereto, and Macquarie US Trading LLC (“Macquarie”), as administrative agent. The credit agreement provides for a $300.0 million senior secured term loan (“Term Loan”). The credit agreement also provides that, subject to satisfaction of certain conditions, the Company may request that the lenders establish an incremental senior secured term loan facility in an aggregate amount not to exceed $200.0 million. The Term Loan initially bears interest at a rate of 7.2% per annum but shall be reduced to 6.2% per annum on the later to occur of (i) FDA approval in the United States of a product with a label claim for treating patients with cystic fibrosis 12 years of age and older who are homozygous with the F508del mutation (“FDA Approval”), and (ii) the one year anniversary of the closing, in each case, until the second anniversary of the closing. On and after the second anniversary of the closing, the Term Loan will bear interest at a rate per annum equal to LIBOR plus 5.0% to 7.5% depending on the receipt of FDA Approval. The maturity date of all loans under the facilities is July 9, 2017. Interest is payable quarterly and on the maturity date. The Company is required to repay principal on the Term Loan in installments of $15.0 million per quarter from October 1, 2015 through July 1, 2016 and in installments of $60.0 million per quarter from October 1, 2016 through the maturity date. The Company may prepay the Term Loan, in whole or in part, at any time; provided that prepayments prior to the second anniversary of the closing are subject to a make-whole premium to ensure Macquarie receives approximately the present value of two years of interest payments over the life of the loan. The Company’s obligations under the Term Loan are unconditionally guaranteed by certain of its domestic subsidiaries. All obligations under the Term Loan, and the guarantees of those obligations, are secured, subject to certain exceptions, by substantially all of the Company’s assets and the assets of all guarantors, including the pledge of all or a portion of the equity interests of certain of its subsidiaries. The credit agreement requires that the Company maintain, on a quarterly basis, a minimum level of KALYDECO net revenues. Further, the credit agreement includes negative covenants, subject to exceptions, restricting or limiting the Company’s ability and the ability of its subsidiaries to, among other things, incur additional indebtedness, grant liens, engage in certain investment, acquisition and disposition transactions, pay dividends, repurchase capital stock and enter into transactions with affiliates. The credit agreement also contains customary representations and warranties, affirmative covenants and events of default, including payment defaults, breach of representations and warranties, covenant defaults and cross defaults. If an event of default occurs, the administrative agent would be entitled to take various actions, including the acceleration of amounts due under outstanding loans. There have been no events of default as of or during the period ended December 31, 2014. Based on the Company’s evaluation of the Term Loan, the Company determined that the Term Loan contains several embedded derivatives. These embedded derivatives are clearly and closely related to the host instrument because they relate to the Company’s credit risk; therefore, they do not require bifurcation from the host instrument, the Term Loan. The Company incurred $5.3 million in fees paid to Macquarie that were recorded as a discount on the Term Loan and that are being recorded as additional interest expense using the effective interest method over the term of the loan in the Company’s consolidated statements of operations. As of December 31, 2014, the unamortized discount associated with the Term Loan that was embedded in the senior secured term loan caption on the Company’s consolidated balance sheet was $5.2 million. Convertible Senior Subordinated Notes In September 2010, the Company completed an offering of $400.0 million in aggregate principal amount of 3.35% convertible senior subordinated notes due 2015 Notes (the “2015 Notes”). This offering resulted in $391.6 million of net proceeds to the Company. The underwriting discount and other expenses of $8.4 million were recorded as debt issuance costs and were included in other assets on the Company’s consolidated balance sheets. The 2015 Notes bore interest at the rate of 3.35% per annum, and the Company was required to make semi-annual interest payments on the outstanding principal balance of the 2015 Notes on April 1 and October 1 of each year. The 2015 Notes were convertible at any time, at the option of the holder, into common stock at a price equal to approximately $48.83 per share, or 20.4794 shares of common stock per $1,000 principal amount of the 2015 Notes, subject to adjustment. If the closing price of the Company’s common stock exceeded 130% of the conversion price for at least 20 trading days within a period of 30 consecutive trading days, the Company had the right to redeem the 2015 Notes at its option at a redemption price equal to 100% of the principal amount of the 2015 Notes to be redeemed. In the second quarter of 2013, the Company’s common stock exceeded 130% of the conversion price of the 2015 Notes for at least 20 trading days within a period of 30 consecutive trading days, and the Company notified the holders of the 2015 Notes that it would redeem the 2015 Notes on June 17, 2013. In response to the Company’s call of the 2015 Notes for redemption, in accordance with the provisions of the 2015 Notes, the holders of $399.8 million in aggregate principal amount of 2015 Notes elected to convert their 2015 Notes into the Company’s common stock at the conversion price of approximately $48.83 per share. As a result of these conversions, the Company issued 8,188,448 shares of common stock. The remaining $0.2 million in aggregate principal amount of 2015 Notes was redeemed on June 17, 2013. Pursuant to the terms of the 2015 Notes, the Company made an additional payment of $16.75 per $1,000 principal amount, payable in shares of the Company’s common stock, to the holders of the 2015 Notes that converted or redeemed their 2015 Notes after the Company called the 2015 Notes for redemption. These payments resulted in the issuance of an additional 87,109 shares of the Company’s common stock. In the second quarter of 2013, the Company recognized an aggregate of $6.7 million in interest expense related to the 2015 Notes. Unamortized debt issuance costs for the 2015 Notes of $4.2 million were recorded as an offset to additional paid-in capital.

Long Term Obligations

Fan Pier Leases

In 2011, the Company entered into two lease agreements, pursuant to which the Company leases approximately 1.1 million square feet of office and laboratory space in two buildings (the “Buildings”) at Fan Pier in Boston, Massachusetts (the “Fan Pier Leases”). The Company commenced lease payments in December 2013, and will make lease payments pursuant to the Fan Pier Leases through December 2028. The Company has an option to extend the term of the Fan Pier Leases for an additional 10 years.

Because the Company was involved in the construction project, the Company was deemed for accounting purposes to be the owner of the Buildings during the construction period and recorded project construction costs incurred by the landlord. Upon completion of the Buildings, the Company evaluated the Fan Pier Leases and determined that the Fan Pier Leases did not meet the criteria for “sale-leaseback” treatment. Accordingly, the Company began depreciating the asset and incurring interest expense related to the financing obligation in 2013. The Company bifurcates its lease payments pursuant to the Fan Pier Leases into (i) a portion that is allocated to the Buildings and (ii) a portion that is allocated to the land on which the Buildings were constructed. The portion of the lease obligations allocated to the land is treated as an operating lease that commenced in 2011. In 2014, the Company recorded $60.2 million in interest expense, $13.4 million in depreciation expense and $6.5 million in rent expense related to the Buildings.

Property and equipment, net, included $515.0 million and $503.4 million as of December 31, 2014 and 2013, respectively, related to construction costs for the Buildings. The carrying value of the construction financing lease obligation related to the Buildings, which excludes interest that will be imputed over the course of the Company’s lease agreement for the Buildings, was $473.4 million and $440.9 million, as of December 31, 2014 and 2013, respectively.

Term Loan

On July 9, 2014, the Company entered into a credit agreement with the lenders party thereto, and Macquarie US Trading LLC (“Macquarie”), as administrative agent. The credit agreement provides for a $300.0 million senior secured term loan (“Term Loan”). The credit agreement also provides that, subject to satisfaction of certain conditions, the Company may request that the lenders establish an incremental senior secured term loan facility in an aggregate amount not to exceed $200.0 million.

The Term Loan initially bears interest at a rate of 7.2% per annum but shall be reduced to 6.2% per annum on the later to occur of (i) FDA approval in the United States of a product with a label claim for treating patients with cystic fibrosis 12 years of age and older who are homozygous with the F508del mutation (“FDA Approval”), and (ii) the one year anniversary of the closing, in each case, until the second anniversary of the closing. On and after the second anniversary of the closing, the Term Loan will bear interest at a rate per annum equal to LIBOR plus 5.0% to 7.5% depending on the receipt of FDA Approval.

The maturity date of all loans under the facilities is July 9, 2017. Interest is payable quarterly and on the maturity date. The Company is required to repay principal on the Term Loan in installments of $15.0 million per quarter from October 1, 2015 through July 1, 2016 and in installments of $60.0 million per quarter from October 1, 2016 through the maturity date. The Company may prepay the Term Loan, in whole or in part, at any time; provided that prepayments prior to the second anniversary of the closing are subject to a make-whole premium to ensure Macquarie receives approximately the present value of two years of interest payments over the life of the loan.

The Company’s obligations under the Term Loan are unconditionally guaranteed by certain of its domestic subsidiaries. All obligations under the Term Loan, and the guarantees of those obligations, are secured, subject to certain exceptions, by substantially all of the Company’s assets and the assets of all guarantors, including the pledge of all or a portion of the equity interests of certain of its subsidiaries.

The credit agreement requires that the Company maintain, on a quarterly basis, a minimum level of KALYDECO net revenues. Further, the credit agreement includes negative covenants, subject to exceptions, restricting or limiting the Company’s ability and the ability of its subsidiaries to, among other things, incur additional indebtedness, grant liens, engage in certain investment, acquisition and disposition transactions, pay dividends, repurchase capital stock and enter into transactions with affiliates. The credit agreement also contains customary representations and warranties, affirmative covenants and events of default, including payment defaults, breach of representations and warranties, covenant defaults and cross defaults. If an event of default occurs, the administrative agent would be entitled to take various actions, including the acceleration of amounts due under outstanding loans. There have been no events of default as of or during the period ended December 31, 2014.

Based on the Company’s evaluation of the Term Loan, the Company determined that the Term Loan contains several embedded derivatives. These embedded derivatives are clearly and closely related to the host instrument because they relate to the Company’s credit risk; therefore, they do not require bifurcation from the host instrument, the Term Loan.

The Company incurred $5.3 million in fees paid to Macquarie that were recorded as a discount on the Term Loan and that are being recorded as additional interest expense using the effective interest method over the term of the loan in the Company’s consolidated statements of operations. As of December 31, 2014, the unamortized discount associated with the Term Loan that was embedded in the senior secured term loan caption on the Company’s consolidated balance sheet was $5.2 million.

Convertible Senior Subordinated Notes

In September 2010, the Company completed an offering of $400.0 million in aggregate principal amount of 3.35% convertible senior subordinated notes due 2015 Notes (the “2015 Notes”). This offering resulted in $391.6 million of net proceeds to the Company. The underwriting discount and other expenses of $8.4 million were recorded as debt issuance costs and were included in other assets on the Company’s consolidated balance sheets. The 2015 Notes bore interest at the rate of 3.35% per annum, and the Company was required to make semi-annual interest payments on the outstanding principal balance of the 2015 Notes on April 1 and October 1 of each year.

The 2015 Notes were convertible at any time, at the option of the holder, into common stock at a price equal to approximately $48.83 per share, or 20.4794 shares of common stock per $1,000 principal amount of the 2015 Notes, subject to adjustment. If the closing price of the Company’s common stock exceeded 130% of the conversion price for at least 20 trading days within a period of 30 consecutive trading days, the Company had the right to redeem the 2015 Notes at its option at a redemption price equal to 100% of the principal amount of the 2015 Notes to be redeemed.

In the second quarter of 2013, the Company’s common stock exceeded 130% of the conversion price of the 2015 Notes for at least 20 trading days within a period of 30 consecutive trading days, and the Company notified the holders of the 2015 Notes that it would redeem the 2015 Notes on June 17, 2013. In response to the Company’s call of the 2015 Notes for redemption, in accordance with the provisions of the 2015 Notes, the holders of $399.8 million in aggregate principal amount of 2015 Notes elected to convert their 2015 Notes into the Company’s common stock at the conversion price of approximately $48.83 per share. As a result of these conversions, the Company issued 8,188,448 shares of common stock. The remaining $0.2 million in aggregate principal amount of 2015 Notes was redeemed on June 17, 2013.

Pursuant to the terms of the 2015 Notes, the Company made an additional payment of $16.75 per $1,000 principal amount, payable in shares of the Company’s common stock, to the holders of the 2015 Notes that converted or redeemed their 2015 Notes after the Company called the 2015 Notes for redemption. These payments resulted in the issuance of an additional 87,109 shares of the Company’s common stock. In the second quarter of 2013, the Company recognized an aggregate of $6.7 million in interest expense related to the 2015 Notes. Unamortized debt issuance costs for the 2015 Notes of $4.2 million were recorded as an offset to additional paid-in capital.