Description of the Business and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2012
Description of the Business and Summary of Significant Accounting Policies [Abstract]
Description of the Business and Summary of Significant Accounting Policies	1. Description of Business and Basis of Presentation Description of Business - Insmed is a biopharmaceutical company focused on developing and commercializing inhaled therapies for patients battling serious orphan lung diseases that are often life threatening. The Company's lead product candidate, ARIKACE®, or liposomal amikacin for inhalation, is an inhaled antibiotic treatment that delivers a proven and potent anti-infective directly to the site of serious lung infections to improve the efficacy, safety and convenience of this therapeutic approach for patients. Currently, the Company is conducting clinical trials of ARIKACE for two initial indications in orphan patient populations: a phase 3 clinical trial in cystic fibrosis (CF) patients who have lung infections caused by Pseudomonasaeruginosa (Pseudomonas) and a phase 2 clinical trial in patients who have lung infections caused by non-tuberculous mycobacteria (NTM). The Company's strategy is to continue to develop ARIKACE for additional indications beyond Pseudomonas and NTM. The Company's primary development focus is to obtain regulatory approval for ARIKACE and to prepare for commercialization initially in Europe, Canada and the United States (US). If approved, ARIKACE will be the first once-a-day inhaled antibiotic treatment option available for these CF and NTM indications. The Company was incorporated in the Commonwealth of Virginia on November 29,1999. On December 1, 2010, the Company completed a business combination with Transave, Inc. (Transave), a privately held, New Jersey-based pharmaceutical company focused on the development of differentiated and innovative inhaled pharmaceuticals for the site-specific treatment of serious lung infections. The integration with Transave was completed in 2011. The Company's continuing operations are based on the technology and products historically developed by Transave. The Company's principal executive offices are located in Monmouth Junction, New Jersey. Basis of Presentation - The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, Transave, LLC, Insmed Pharmaceuticals, Incorporated, Insmed Limited and Celtrix Pharmaceuticals, Incorporated (Celtrix). All significant intercompany balances and transactions have been eliminated in consolidation.

The entire disclosure for the organization, consolidation and basis of presentation of financial statements disclosure, and significant accounting policies of the reporting entity. May be provided in more than one note to the financial statements, as long as users are provided with an understanding of (1) the significant judgments and assumptions made by an enterprise in determining whether it must consolidate a VIE and/or disclose information about its involvement with a VIE, (2) the nature of restrictions on a consolidated VIE's assets reported by an enterprise in its statement of financial position, including the carrying amounts of such assets, (3) the nature of, and changes in, the risks associated with an enterprise's involvement with the VIE, and (4) how an enterprise's involvement with the VIE affects the enterprise's financial position, financial performance, and cash flows. Describes procedure if disclosures are provided in more than one note to the financial statements.

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