Subsequent Events	6 Months Ended
Jun. 30, 2017
Subsequent Events [Abstract]
Subsequent Events	16. SUBSEQUENT EVENTS In July 2017, the Company and the University of Western Australia (“UWA”) on one hand entered into a settlement agreement with BioMarin Leiden Holding BV, its subsidiaries BioMarin Nederlands BV and BioMarin Technologies BV (collectively, “BioMarin”), and on the same day the Company entered into a license agreement with BioMarin and Academisch Ziekenhuis Leiden (“AZL”, and collectively with the Company, UWA and BioMarin, the “Settlement Parties”). On the same day, the Company entered into a license agreement with BioMarin. Under these agreements, BioMarin agrees to provide the Company with an exclusive license to certain intellectual property with an option to convert the exclusive license into a co-exclusive license and the Settlement Parties agree to stop most existing efforts to continue with ongoing litigation and opposition and other administrative proceedings concerning BioMarin’s intellectual property. Under terms of the agreements, the Company agrees to make total up-front payments of $35.0 million upon execution of the agreements, consisting of $20.0 million under the settlement agreement and $15.0 million under the license agreement. Additionally, the Company may be liable for up to approximately $65.0 million in regulatory and sales milestones for eteplirsen as well as exon 45 and exon 53 skipping product candidates. BioMarin will also be eligible to receive royalty payments, ranging from 4% - 8% which for defined exon 51 skipping products, exon 45 skipping products and exon 53 skipping products will expire in December 2023 in the U.S. and September 2024 in the EU. For the three and six months ended June 30, 2017, the Company recognized a settlement charge of $2.8 million which related to estimated royalties between September 2016 and June 2017. In July 2017, the Company entered into an amended and restated credit agreement (the “Amended and Restated Credit and Security Agreement”) which provides a term loan of $60.0 million and a revolving credit and security agreement (the “Revolving Credit Agreement”) which provides an aggregate revolving loan commitment of $40.0 million (which may be increased by an additional tranche of $20.0 million) with MidCap Financial Trust. Borrowings under the Amended and Restated Credit and Security Agreement bear interest at a rate per annum equal to 6.25%, plus one-month London Interbank Offered Rate (“LIBOR”), and borrowings under the Revolving Credit Agreement bear interest at a rate of 3.95%, plus one-month LIBOR. In addition to paying interest on the outstanding principal under the Amended and Restated Credit and Security Agreement, the Company will pay (i) an origination fee equal to 0.50% of the amount of the term loan when advanced under the Amended and Restated Credit and Security Agreement, (ii) and origination fee equal to 0.50% of the amount of the revolving loan when advanced under the Revolving Credit Agreement, (iii) a final payment fee equal to 2.00% of the amount borrowed under the Amended and Restated Credit and Security Agreement when the term loan is fully repaid and (iv) an unused line fee, minimum balance fee, collateral fee, deferred revolving loan original fee and certain other fees under the Revolving Credit Agreement. Commencing on July 1, 2018, and continuing for the remaining thirty six months of the facility, the Company will be required to make monthly principal payments based on the straight-line amortization schedule set forth in the Amended and Restated Credit and Security Agreement, subject to certain adjustments as described therein. Both facilities mature in July 2021. As of the date of the issuance of this report, the Company has received $34.8 million of net proceeds for the debt offerings, net of approximately $9.2 million repayment of the outstanding loan payable and $1.1 million of fees. In July 2017, the Company sold approximately 8.8 million shares of common stock through an underwritten public offering, including 1.2 million shares sold to the underwriters. The offering price was $42.50 per share. As of the date of the issuance of this report, the Company expected to receive net proceeds of approximately $354.0 million from the offering, net of commission and offering expenses of approximately $19.9 million.

16. SUBSEQUENT EVENTS

In July 2017, the Company and the University of Western Australia (“UWA”) on one hand entered into a settlement agreement with BioMarin Leiden Holding BV, its subsidiaries BioMarin Nederlands BV and BioMarin Technologies BV (collectively, “BioMarin”), and on the same day the Company entered into a license agreement with BioMarin and Academisch Ziekenhuis Leiden (“AZL”, and collectively with the Company, UWA and BioMarin, the “Settlement Parties”). On the same day, the Company entered into a license agreement with BioMarin. Under these agreements, BioMarin agrees to provide the Company with an exclusive license to certain intellectual property with an option to convert the exclusive license into a co-exclusive license and the Settlement Parties agree to stop most existing efforts to continue with ongoing litigation and opposition and other administrative proceedings concerning BioMarin’s intellectual property. Under terms of the agreements, the Company agrees to make total up-front payments of $35.0 million upon execution of the agreements, consisting of $20.0 million under the settlement agreement and $15.0 million under the license agreement. Additionally, the Company may be liable for up to approximately $65.0 million in regulatory and sales milestones for eteplirsen as well as exon 45 and exon 53 skipping product candidates. BioMarin will also be eligible to receive royalty payments, ranging from 4% - 8% which for defined exon 51 skipping products, exon 45 skipping products and exon 53 skipping products will expire in December 2023 in the U.S. and September 2024 in the EU. For the three and six months ended June 30, 2017, the Company recognized a settlement charge of $2.8 million which related to estimated royalties between September 2016 and June 2017.

In July 2017, the Company entered into an amended and restated credit agreement (the “Amended and Restated Credit and Security Agreement”) which provides a term loan of $60.0 million and a revolving credit and security agreement (the “Revolving Credit Agreement”) which provides an aggregate revolving loan commitment of $40.0 million (which may be increased by an additional tranche of $20.0 million) with MidCap Financial Trust. Borrowings under the Amended and Restated Credit and Security Agreement bear interest at a rate per annum equal to 6.25%, plus one-month London Interbank Offered Rate (“LIBOR”), and borrowings under the Revolving Credit Agreement bear interest at a rate of 3.95%, plus one-month LIBOR. In addition to paying interest on the outstanding principal under the Amended and Restated Credit and Security Agreement, the Company will pay (i) an origination fee equal to 0.50% of the amount of the term loan when advanced under the Amended and Restated Credit and Security Agreement, (ii) and origination fee equal to 0.50% of the amount of the revolving loan when advanced under the Revolving Credit Agreement, (iii) a final payment fee equal to 2.00% of the amount borrowed under the Amended and Restated Credit and Security Agreement when the term loan is fully repaid and (iv) an unused line fee, minimum balance fee, collateral fee, deferred revolving loan original fee and certain other fees under the Revolving Credit Agreement. Commencing on July 1, 2018, and continuing for the remaining thirty six months of the facility, the Company will be required to make monthly principal payments based on the straight-line amortization schedule set forth in the Amended and Restated Credit and Security Agreement, subject to certain adjustments as described therein. Both facilities mature in July 2021. As of the date of the issuance of this report, the Company has received $34.8 million of net proceeds for the debt offerings, net of approximately $9.2 million repayment of the outstanding loan payable and $1.1 million of fees.

In July 2017, the Company sold approximately 8.8 million shares of common stock through an underwritten public offering, including 1.2 million shares sold to the underwriters. The offering price was $42.50 per share. As of the date of the issuance of this report, the Company expected to receive net proceeds of approximately $354.0 million from the offering, net of commission and offering expenses of approximately $19.9 million.