License and Collaborative Agreements	12 Months Ended
Dec. 31, 2012
License and Collaborative Agreements [Abstract]
License and Collaborative Agreements	12. License and Collaboration Agreements In-License Agreements Ipsen and Genentech - In March 2007, the Company was granted a license or sublicense as applicable to patents held by Ipsen and Genentech to develop IPLEX in certain medical indications in the US and foreign territories. In November 2008, the Company gained Royalty-Free Worldwide Rights for IPLEX from Ipsen and Genentech in connection with potential expanded access ALS programs. PARI Pharma GmbH - In April 2008, the Company entered into a licensing agreement with PARI Pharma GmbH for use of the optimized eFlow Nebulizer System for delivery of ARIKACE in treating patients with CF, bronchiectasis, and NTM infections. Insmed has rights to several US and foreign issued patents and patent applications involving improvements to the optimized eFlow Nebulizer System. In consideration of this agreement, PARI shall receive payments either in cash, qualified stock or a combination of both, at PARI's discretion, based on achievement of certain future milestone events including first acceptance of MAA submission (or equivalent) in the US of ARIKACE and the device, first receipt of marketing approval in the US for ARIKACE and the device, and first receipt of marketing approval in a major EU country for ARIKACE. In addition, PARI will receive royalty payments on commercial sales of ARIKACE. Out-License Agreements NAPO Pharmaceuticals - In January 2007, the Company entered into an agreement with NAPO Pharmaceuticals, whereby it granted NAPO a license for INSM-18 also known as Masoprocal. The license gives NAPO the right to develop, manufacture and commercialize Masoprocal products for any indications relating specifically to diabetes, cardiac disease, vascular disease, metabolic disease and Syndrome X. The agreement calls for payments from NAPO to the Company upon the achievement of certain milestones which have not yet been met. TriAct - In December, 2010, the Company entered into an agreement with TriAct Therapeutics Inc. ("TriAct") whereby it granted TriAct an exclusive license for INS-18 also known as Masoprocal. The license gives TriAct the right to develop, manufacture and commercialize Masoprocal products for any indications relating specifically to oncology. The agreement calls for the issue of TriAct common stock to Insmed upon the achievement of certain milestones. To date, no milestones have been achieved and no common stock has been received. Eleison - In February, 2011, the Company entered into an agreement with Eleison Pharmaceuticals whereby it granted Eleison an exclusive license for CISPLATIN Lipid Complex. The license gives Eleison the right to develop, manufacture and commercialize CISPLATIN Lipid Complex. Payments totaling $1.0 million were received in 2011 and were recorded as license fee revenue. Premacure (now Shire plc) - In May, 2012, the Company entered into an agreement with Premacure Holdings AB and Premacure AB of Sweden (collectively, "Premacure") pursuant to which the Company granted to Premacure an exclusive, worldwide license to develop manufacture and commercialize IGF-1, with its natural binding protein, IGFBP-3, for the prevention and treatment of complications of preterm birth. (the " Premacure License Agreement"). In March 2013, we amended the Premacure License Agreement to provide Premacure with the option, exercisable by Premacure any time prior to April 30, 2013, to pay us $11.5 million and assume any of our royalty obligations to other parties in exchange for a fully paid license. If Premacure exercises this option, we would not be entitled to future royalties from Premacure. Collaboration Agreements Cystic Fibrosis Foundation Therapeutics, Inc. - In 2005 and 2009, the Company entered into research funding agreements with Cystic Fibrosis Foundation Therapeutics, Inc. (CFFT) whereby it received $1.7 million and $2.2 million for each respective agreement in research funding for the development of its ARIKACE product. If ARIKACE becomes an approved product for CF in the US, the Company will owe payments totaling up to $13.4 million to CFFT that would be payable over a three-year period after approval as a commercialized drug in the US. Furthermore, if certain sales milestones are met within 5 years of the drug commercialization approval in the US, the Company would owe an additional payment of $3.9 million. Since there is significant development risk associated with ARIKACE, we have not accrued these obligations. National Institutes of Allergy and Infectious Diseases - In 2009 and 2012, we entered into a cooperative research and development agreement (CRADA) with National Institutes of Allergy and Infectious Diseases (NIAID) to design and conduct our phase 2 study of ARIKACE in patients with NTM. NIAID has also agreed to provide biostatistical advisory input in connection with the phase 2 NTM study. If we decide not to continue with the commercialization of ARIKACE in NTM, NIAID will have the right to complete the clinical trial. Further, NIAID may elect to pursue its rights to obtain license rights to certain inventions made under the CRADA.

12. License and Collaboration Agreements

In-License Agreements

Ipsen and Genentech - In March 2007, the Company was granted a license or sublicense as applicable to patents held by Ipsen and Genentech to develop IPLEX in certain medical indications in the US and foreign territories. In November 2008, the Company gained Royalty-Free Worldwide Rights for IPLEX from Ipsen and Genentech in connection with potential expanded access ALS programs.

PARI Pharma GmbH - In April 2008, the Company entered into a licensing agreement with PARI Pharma GmbH for use of the optimized eFlow Nebulizer System for delivery of ARIKACE in treating patients with CF, bronchiectasis, and NTM infections. Insmed has rights to several US and foreign issued patents and patent applications involving improvements to the optimized eFlow Nebulizer System. In consideration of this agreement, PARI shall receive payments either in cash, qualified stock or a combination of both, at PARI's discretion, based on achievement of certain future milestone events including first acceptance of MAA submission (or equivalent) in the US of ARIKACE and the device, first receipt of marketing approval in the US for ARIKACE and the device, and first receipt of marketing approval in a major EU country for ARIKACE. In addition, PARI will receive royalty payments on commercial sales of ARIKACE.

Out-License Agreements

NAPO Pharmaceuticals - In January 2007, the Company entered into an agreement with NAPO Pharmaceuticals, whereby it granted NAPO a license for INSM-18 also known as Masoprocal. The license gives NAPO the right to develop, manufacture and commercialize Masoprocal products for any indications relating specifically to diabetes, cardiac disease, vascular disease, metabolic disease and Syndrome X. The agreement calls for payments from NAPO to the Company upon the achievement of certain milestones which have not yet been met.

TriAct - In December, 2010, the Company entered into an agreement with TriAct Therapeutics Inc. ("TriAct") whereby it granted TriAct an exclusive license for INS-18 also known as Masoprocal. The license gives TriAct the right to develop, manufacture and commercialize Masoprocal products for any indications relating specifically to oncology. The agreement calls for the issue of TriAct common stock to Insmed upon the achievement of certain milestones. To date, no milestones have been achieved and no common stock has been received.

Eleison - In February, 2011, the Company entered into an agreement with Eleison Pharmaceuticals whereby it granted Eleison an exclusive license for CISPLATIN Lipid Complex. The license gives Eleison the right to develop, manufacture and commercialize CISPLATIN Lipid Complex. Payments totaling $1.0 million were received in 2011 and were recorded as license fee revenue.

Premacure (now Shire plc) - In May, 2012, the Company entered into an agreement with Premacure Holdings AB and Premacure AB of Sweden (collectively, "Premacure") pursuant to which the Company granted to Premacure an exclusive, worldwide license to develop manufacture and commercialize IGF-1, with its natural binding protein, IGFBP-3, for the prevention and treatment of complications of preterm birth. (the " Premacure License Agreement"). In March 2013, we amended the Premacure License Agreement to provide Premacure with the option, exercisable by Premacure any time prior to April 30, 2013, to pay us $11.5 million and assume any of our royalty obligations to other parties in exchange for a fully paid license. If Premacure exercises this option, we would not be entitled to future royalties from Premacure.

Collaboration Agreements

Cystic Fibrosis Foundation Therapeutics, Inc. - In 2005 and 2009, the Company entered into research funding agreements with Cystic Fibrosis Foundation Therapeutics, Inc. (CFFT) whereby it received $1.7 million and $2.2 million for each respective agreement in research funding for the development of its ARIKACE product. If ARIKACE becomes an approved product for CF in the US, the Company will owe payments totaling up to $13.4 million to CFFT that would be payable over a three-year period after approval as a commercialized drug in the US. Furthermore, if certain sales milestones are met within 5 years of the drug commercialization approval in the US, the Company would owe an additional payment of $3.9 million. Since there is significant development risk associated with ARIKACE, we have not accrued these obligations.

National Institutes of Allergy and Infectious Diseases - In 2009 and 2012, we entered into a cooperative research and development agreement (CRADA) with National Institutes of Allergy and Infectious Diseases (NIAID) to design and conduct our phase 2 study of ARIKACE in patients with NTM. NIAID has also agreed to provide biostatistical advisory input in connection with the phase 2 NTM study. If we decide not to continue with the commercialization of ARIKACE in NTM, NIAID will have the right to complete the clinical trial. Further, NIAID may elect to pursue its rights to obtain license rights to certain inventions made under the CRADA.