Insmed (INSM) 10-K 27 Feb 15 2014 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Feb. 02, 2015	Jun. 30, 2014
Document and Entity Information
Entity Registrant Name	INSMED INC
Entity Central Index Key	1104506
Document Type	10-K
Document Period End Date	31-Dec-14
Amendment Flag	FALSE
Current Fiscal Year End Date	-19
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$772.70
Entity Common Stock, Shares Outstanding		49,994,137
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$159,226	$113,894
Prepaid expenses and other current assets	5,488	2,269
Total current assets	164,714	116,163
In-process research and development	58,200	58,200
Fixed assets, net	7,534	1,812
Other assets	416	323
Total assets	230,864	176,498
Current liabilities:
Accounts payable	9,249	5,929
Accrued expenses	5,321	3,905
Accrued compensation	4,317	2,839
Accrued lease expense, current	320	307
Deferred rent	423	129
Capital lease obligations, current		64
Current portion of long term debt		3,283
Total current liabilities	19,630	16,456
Long-term liabilities:
Accrued lease expense, long-term	118	380
Other long-term liabilities	23
Debt, long-term	24,856	16,338
Total liabilities	44,627	33,174
Shareholders' equity:
Common stock, $0.01 par value; 500,000,000 authorized shares, 49,806,131 and 39,137,169 issued and outstanding shares at December 31, 2014 and December 31, 2013, respectively	498	391
Additional paid-in capital	656,519	534,554
Accumulated deficit	-470,780	-391,621
Total shareholders' equity	186,237	143,324
Total liabilities and shareholders' equity	$230,864	$176,498

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Consolidated Balance Sheets
Common stock, par value (in dollars per share)	$0.01	$0.01
Common stock, authorized shares	500,000,000	500,000,000
Common stock, issued shares	49,806,131	39,137,169
Common stock, outstanding shares	49,806,131	39,137,169

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Consolidated Statements of Comprehensive Loss
Other revenue		$11,500
Total revenues		11,500
Operating expenses:
Research and development	56,292	44,279	29,781
General and administrative	31,073	22,236	12,657
Total operating expenses	87,365	66,515	42,438
Operating loss	-87,365	-55,015	-42,438
Investment income	58	166	1,822
Interest expense	-2,415	-2,412	-763
Other income / (expense), net	141	-33	5
Loss before income taxes	-89,581	-57,294	-41,374
Benefit from income taxes	-10,422	-1,221	0
Net loss	-79,159	-56,073	-41,374
Basic and diluted net loss per share (in dollars per share)	($1.84)	($1.60)	($1.56)
Weighted average basic and diluted common shares outstanding (in shares)	43,095	34,980	26,545
Net loss	-79,159	-56,073	-41,374
Comprehensive loss:
Unrealized loss on investments, net of taxes			-450
Comprehensive loss	($79,159)	($56,073)	($41,824)

Consolidated_Statements_of_Sto

Consolidated Statements of Stockholders' Equity (USD $)	Common Stock	Warrant	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Total
In Thousands, except Share data, unless otherwise specified
Balance at Dec. 31, 2011	$248		$427,743	($294,174)	$450	$134,267
Balance (in shares) at Dec. 31, 2011	24,833,000
Comprehensive loss:
Net loss				-41,374		-41,374
Unrealized loss on investments, net					-450	-450
Exercise of stock options	1		213			214
Exercise of stock options (in shares)	30,000					30,250
Net proceeds from issuance of common stock	63		25,595			25,658
Net proceeds from issuance of common stock (in shares)	6,304,000
Issuance of common stock for vesting of RSUs	3		-3
Issuance of common stock for vesting of RSUs (in shares)	321,000
Fair value of warrants granted in connection with debt financing		790				790
Fair value of warrants granted in connection with debt financing (in shares)		330,000
Stock compensation expense			1,777			1,777
Balance at Dec. 31, 2012	315	790	455,325	-335,548		120,882
Balance (in shares) at Dec. 31, 2012	31,488,000	330,000
Comprehensive loss:
Net loss				-56,073		-56,073
Exercise of stock options	4		1,622			1,626
Exercise of stock options (in shares)	372,000					371,743
Net proceeds from issuance of common stock	69		66,948			67,017
Net proceeds from issuance of common stock (in shares)	6,900,000
Issuance of common stock for vesting of RSUs	1		-1
Issuance of common stock for vesting of RSUs (in shares)	154,000
Exercise of warrants	2	-790	788
Exercise of warrants (in shares)	223,000	-330,000
Reclass of stock compensation expense for liability awards to equity			3,371			3,371
Stock compensation expense			6,501			6,501
Balance at Dec. 31, 2013	391		534,554	-391,621		143,324
Balance (in shares) at Dec. 31, 2013	39,137,000
Comprehensive loss:
Net loss				-79,159		-79,159
Exercise of stock options	3		1,728			1,731
Exercise of stock options (in shares)	283,000					283,057
Net proceeds from issuance of common stock	103		108,910			109,013
Net proceeds from issuance of common stock (in shares)	10,306,000
Issuance of common stock for vesting of RSUs	1		-1
Issuance of common stock for vesting of RSUs (in shares)	80,000
Stock compensation expense			11,328			11,328
Balance at Dec. 31, 2014	$498		$656,519	($470,780)		$186,237
Balance (in shares) at Dec. 31, 2014	49,806,000

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net loss	($79,159)	($56,073)	($41,374)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,073	680	561
Stock based compensation expense	11,328	8,668	2,981
Loss / (gain) on sale of asset, net	9	-2	-5
Gain on sale of short-term investments, net			-833
Amortization of debt discount and debt issuance costs	390	333	236
Accrual of the end of term charge on the debt	110	160	44
Changes in operating assets and liabilities:
Accounts receivable			757
Prepaid expenses and other assets	-2,972	-1,832	-180
Accounts payable	3,312	-1,131	4,726
Accrued expenses, deferred rent and other	264	2,156	922
Accrued lease expenses	-249	-255	-259
Accrued compensation	1,478	632	1,412
Net cash used in operating activities	-64,416	-46,664	-31,012
Investing activities
Purchase of fixed assets	-5,351	-826	-290
Proceeds from sale of asset	10	2	5
Maturity of a certificate of deposit		2,153
Sales of short-term investments			81,464
Purchases of short-term investments			-19,657
Net cash (used in) / provided by investing activities	-5,341	1,329	61,522
Financing activities
Payments on capital lease obligations	-64	-96	-120
Proceeds from issuance of debt	5,000		20,000
Proceeds from issuance of common stock	109,013	67,017	25,658
Proceeds from exercise of stock options	1,390	1,626	214
Payment of debt issuance costs	-250	-100	-328
Net cash provided by financing activities	115,089	68,447	45,424
Increase in cash and cash equivalents	45,332	23,112	75,934
Cash and cash equivalents at beginning of period	113,894	90,782	14,848
Cash and cash equivalents at end of period	159,226	113,894	90,782
Supplemental disclosures of cash flow information:
Cash paid for interest	1,803	1,809	398
Cash received for taxes, net	9,429	1,221
Supplemental disclosures of non-cash investing and financing activities:
Unrealized loss on investments			450
Value of warrant exercised by converting the warrant into shares of common stock ("net issuance method")		790
Fair value of warrant granted in connection with debt financing			$790

Description_of_Business_and_Ba

Description of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2014
Description of Business and Basis of Presentation
Description of Business and Basis of Presentation	1.        Description of Business and Basis of Presentation
	Description of Business—Insmed is a biopharmaceutical company dedicated to improving the lives of patients battling serious lung diseases. The Company is focused on the development and commercialization of ARIKAYCE, or liposomal amikacin for inhalation, for at least two identified orphan patient populations: patients with nontuberculous mycobacteria (NTM) lung infections and cystic fibrosis (CF) patients with Pseudomonas aeruginosa lung infections. The Company is also focused on the development of INS1009, an inhaled treprostinil prodrug. Treprostinil is a prostacyclin used in the treatment of pulmonary arterial hypertension (PAH), a chronic, life-threatening disorder characterized by abnormally high blood pressure in the arteries between the heart and lungs.
	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 treatment of serious lung infections. 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 Bridgewater, 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, Celtrix Pharmaceuticals, Incorporated (Celtrix), Insmed Holdings Limited and Insmed Ireland Limited. All significant intercompany balances and transactions have been eliminated in consolidation.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2.        Summary of Significant Accounting Policies
	Use of Estimates—The preparation of the consolidated financial statements in conformity with accounting principles generally accepted in the United States (GAAP) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions. The amounts of assets and liabilities reported in the Company's balance sheets and the amounts of expenses reported for each period presented are effected by estimates and assumptions, which are used for, but not limited to, the accounting for stock-based compensation, income taxes, loss contingencies, and accounting for research and development costs. Actual results could differ from those estimates.
	Investment Income and Interest Expense—Investment income consists of interest and dividend income earned on the Company's cash, cash equivalents and short-term investments, along with realized gains (losses) on the sale of investments. Interest expense consists primarily of interest costs related to the Company's debt.
	Cash and Cash Equivalents—The Company considers cash equivalents to be highly liquid investments with maturities of three months or less from the date of purchase.
	Fixed Assets, Net—Fixed assets are recorded at cost and are depreciated on a straight-line basis over the estimated useful lives of the assets. Estimated useful lives of three to five years are used for computer equipment. Estimated useful lives of seven years are used for laboratory equipment, office equipment and furniture and fixtures. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the asset. Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, then an impairment charge is recognized for the amount by which the carrying value of the asset exceeds the fair value of the asset.
	Identifiable Intangible Assets—Identifiable intangible assets are measured at their respective fair values and are not amortized until commercialization. Once commercialization occurs, these intangible assets will be amortized over their estimated useful lives. The fair values assigned to the Company's intangible assets are based on reasonable estimates and assumptions given available facts and circumstances. Unanticipated events or circumstances may occur that may require the Company to review the assets for impairment. Events or circumstances that may require an impairment assessment include negative clinical trial results, the non-approval of a new drug application by a regulatory agency, material delays in the Company's development program or a sustained decline in market capitalization.
	Indefinite-lived intangible assets are not subject to periodic amortization. Rather, indefinite-lived intangibles are reviewed for impairment by applying a fair value based test on an annual basis or more frequently if events or circumstances indicate impairment may have occurred. Events or circumstances that may require an interim impairment assessment are consistent with those described above. The Company performs its annual impairment test as of October 1 of each year.
	The Company uses the income approach to derive the fair value of in-process research and development assets. This approach calculates fair value by estimating future cash flows attributable to the assets and then discounting these cash flows to a present value using a risk-adjusted discount rate. A market based valuation approach was not considered given a lack of revenues and profits for the Company. This approach requires significant management judgment with respect to unobservable inputs such as future volume, revenue and expense growth rates, changes in working capital use, appropriate discount rates and other assumptions and estimates. The estimates and assumptions used are consistent with the Company's business plans.
	Debt Issuance Costs—Debt issuance costs are amortized using the effective interest rate method and amortized to interest expense over the term of the debt. Debt issuance costs paid to the lender are reflected as a discount to the debt, and debt issuance costs paid to other third parties are reflected as other assets in the consolidated balance sheets.
	Fair Value Measurements—The Company categorizes its financial assets and liabilities measured and reported at fair value in the financial statements on a recurring basis based upon the level of judgments associated with the inputs used to measure their fair value. Hierarchical levels, which are directly related to the amount of subjectivity associated with the inputs used to determine the fair value of financial assets and liabilities, are as follows:
		Level 1—Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.
		Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the assets or liability through correlation with market data at the measurement date and for the duration of the instrument's anticipated life.
		Level 3—Inputs reflect management's best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.
	Each major category of financial assets and liabilities measured at fair value on a recurring basis are categorized based upon the lowest level of significant input to the valuations. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Financial instruments in Level 1 generally include US treasuries and mutual funds listed in active markets.
	The Company's only assets and liabilities which were measured at fair value as of December 31, 2014 and December 31, 2013 were its cash and cash equivalents of $159.2 million and $113.9 million, respectively. These amounts were measured at Level 1 using quoted prices in active markets for identical assets at the measurement date. The Company's cash and cash equivalents permit daily redemption and the fair values of these investments are based upon the quoted prices in active markets provided by the holding financial institutions. Cash equivalents consist of liquid investments with a maturity of three months or less from the date of purchase and the short-term investments consist of instruments with maturities greater than three months.
	The Company recognizes transfers between levels within the fair value hierarchy, if any, at the end of each quarter. There were no transfers in or out of Level 1, Level 2 or Level 3 during 2014 and 2013.
	As of December 31, 2014 and 2013, the Company held no securities that were in an unrealized loss or gain position. The Company's unrealized loss on investments for the year ended 2012 was $0.5 million, which was included in other comprehensive loss. During 2012, the Company realized a net gain of $0.8 million from the sale of short term investments.
	The Company reviews the status of each security quarterly to determine whether an other-than-temporary impairment has occurred. In making its determination, the Company considers a number of factors, including: (1) the significance of the decline, (2) whether the securities were rated below investment grade, (3) how long the securities have been in an unrealized loss position, and (4) the Company's ability and intent to retain the investment for a sufficient period of time for it to recover.
	Concentration of Credit Risk—Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents. The Company places its cash equivalents with high credit-quality financial institutions and may invest its short-term investments in US treasury securities, mutual funds and government agency bonds. The Company has established guidelines relative to credit ratings and maturities that seek to maintain safety and liquidity.
	The Company sources its raw materials from single suppliers. In addition, the production of the Company's lead product candidate, ARIKAYCE, is currently performed by a sole manufacturer. In February 2014, the Company entered into a contract manufacturing agreement with a second manufacturer to construct a production area and eventually supply ARIKAYCE at the larger scales necessary to support commercialization. The inability of the suppliers or manufacturers to fulfill supply requirements of the Company could materially impact future operating results. A change in the relationship with the suppliers or manufacturer, or an adverse change in their business, could materially impact future operating results.
	Revenue Recognition—The Company did not recognize any revenue in 2014 and 2012. In 2013, the Company's other revenue solely consists of an $11.5 million payment received from Premacure (now Shire plc) in exchange for the Company's right to receive royalties under its license agreement with Premacure. The Company recorded this as other revenue after all four revenue recognition criteria were present and the Company had no continuing performance obligations related to the payment received.
	The Company recognizes revenues when all of the following four criteria are present: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the fee is fixed or determinable; and collectability is reasonably assured.
	Where the Company has continuing performance obligations under the terms of a collaborative arrangement, non-refundable upfront license payments received upon contract signing are recorded as deferred revenue and recognized as revenue as the related activities are performed. The period over which these activities are to be performed is based upon management's estimate of the development period. Changes in management's estimate could change the period over which revenue is recognized. Research and/or development payments are recognized as revenues as the related research and/or development activities are performed and when the Company has no continuing performance obligations related to the research and development payment received.
	Where the Company has no continuing involvement under a collaborative arrangement, the Company records nonrefundable license fee revenues when the Company has the contractual right to receive the payment, in accordance with the terms of the collaboration agreement, and records milestones upon appropriate notification to the Company of achievement of the milestones by the collaborative partner.
	The Company recognizes revenue from milestone payments when earned, provided that (i) the milestone event is substantive and its achievability was not reasonably assured at the inception of the agreement and (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone earned. Milestone payments are considered substantive if all of the following conditions are met: the milestone payment (a) is commensurate with either the vendor's performance to achieve the milestone or the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the vendor's performance to achieve the milestone, (b) relates solely to past performance, and (c) is reasonable relative to all of the deliverables and payment terms (including other potential milestone consideration) within the arrangement. Any amounts received under the agreement in advance of performance, if deemed substantive, are recorded as deferred revenue and recognized as revenue as the Company completes its performance obligations.
	With regard to recognizing revenue for multiple deliverable revenue arrangements, each deliverable within a multiple-deliverable revenue arrangement is accounted for as a separate unit of accounting if both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company's control.
	In addition, multiple deliverable revenue arrangement consideration is allocated at the inception of an arrangement to all deliverables using the relative selling price method. The Company also applies a selling price hierarchy for determining the selling price of a deliverable, which includes (1) vendor-specific objective evidence, if available, (2) third-party evidence, if vendor-specific objective evidence is not available, and (3) estimated selling price if neither vendor-specific nor third-party evidence is available.
	Deferred revenue associated with a non-refundable payment received under a collaborative agreement that is terminated prior to its completion results in an immediate recognition of the deferred revenue.
	Research and Development—Research and development expenses consist primarily of salaries, benefits and other related costs, including stock based compensation, for personnel serving in the Company's research and development functions, and other internal operating expenses, the cost of manufacturing a drug candidate, including the medical devices for drug delivery, for clinical study, the cost of conducting clinical studies, and the cost of conducting preclinical and research activities. The Company's expenses related to manufacturing its drug candidate and medical devices for clinical study are primarily related to activities at contract manufacturing organizations that manufacture ARIKAYCE and the medical devices for the Company's use. The Company's expenses related to clinical trials are primarily related to activities at contract research organizations that conduct and manage clinical trials on the Company's behalf. These contracts set forth the scope of work to be completed at a fixed fee or amount per patient enrolled. Payments under these contracts primarily depend on performance criteria such as the successful enrollment of patients or the completion of clinical trial milestones as well as time-based fees. Expenses are accrued based on contracted amounts applied to the level of patient enrollment and to activity according to the clinical trial protocol. Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are then recognized as an expense as the related goods are delivered or the services are performed, or when the goods or services are no longer expected to be provided.
	Stock-Based Compensation—The Company recognizes stock-based compensation expense for awards of equity instruments to employees and directors based on the grant-date fair value of those awards. The grant-date fair value of the award is recognized as compensation expense ratably over the requisite service period, which generally equals the vesting period of the award, and if applicable, is adjusted for expected forfeitures. The Company also grants performance-based stock options to employees. The grant-date fair value of the performance-based stock options is recognized as compensation expense over the implicit service period using the accelerated attribution method once it is probable that the performance condition will be achieved. Stock-based compensation expense is included in both research and development expenses and general and administrative expenses in the Consolidated Statements of Comprehensive Loss.
	Certain awards deemed to be granted outside of the Company's equity incentive plans require the Company to use liability accounting. These awards are classified as a liability and are remeasured at fair value at the end of each reporting period until such time they are deemed to be granted under the Company's equity incentive plans. Changes in fair value are included in compensation expense in the Consolidated Statements of Comprehensive Loss (see additional disclosures related to awards granted outside of the 2000 Stock Incentive Plan in Note 8, Stock-Based Compensation).
	Income Taxes—The Company accounts for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.
	A valuation allowance is recorded to reduce the deferred tax assets to the amount that is expected to be realized. In evaluating the need for a valuation allowance, the Company takes into account various factors, including the expected level of future taxable income and available tax planning strategies. If actual results differ from the assumptions made in the evaluation of a valuation allowance, the Company records a change in valuation allowance through income tax expense in the period such determination is made.
	The Company uses a comprehensive model for how it measures, presents and discloses an uncertain tax position taken or expected to be taken in a tax return. The Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by taxing authorities, based solely on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than 50% likelihood to be sustained upon ultimate settlement. The Company has no uncertain tax positions as of December 31, 2014 that qualify for either recognition or disclosure in the consolidated financial statements.
	The Company's policy for interest and penalties related to income tax exposures is to recognize interest and penalties as a component of the income taxes on continuing operations in the Consolidated Statements of Comprehensive Loss.
	Net Loss Per Common Share—Basic net loss per common share is computed by dividing net loss attributable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted net loss per common share is computed by dividing net loss by the weighted average number of common shares and other dilutive securities outstanding during the period. Potentially dilutive securities from stock options, restricted stock units and warrants to purchase common stock would be antidilutive as the Company incurred a net loss in all periods presented. Potentially dilutive common shares resulting from the assumed exercise of outstanding stock options and warrants are determined based on the treasury stock method.
	The following table sets forth the reconciliation of the weighted average number of shares used to compute basic and diluted net loss per share for the years ended December 31, 2014, 2013 and 2012.
			Years Ended December 31,
			2014			2013			2012
			(In thousands, except per share amounts)
	Numerator:
	Net loss:		$	(79,159	)	$	(56,073	)	$	(41,374	)
	Denominator:
	Weighted average common shares used in calculation of basic net loss per share:			43,095			34,980			26,545
	Effect of dilutive securities:
	Common stock options			-			-			-
	Restricted stock and restricted stock units			-			-			-
	Common stock warrant			-			-			-
	Weighted average common shares outstanding used in calculation of diluted net loss per share			43,095			34,980			26,545
	Net loss per share:
	Basic and Diluted		$	(1.84	)	$	(1.60	)	$	(1.56	)
	The following potentially dilutive securities have been excluded from the computations of diluted weighted-average common shares outstanding as of December 31, 2014, 2013 and 2012 as their effect would have been anti-dilutive (in thousands).
			2014			2013			2012
	Warrants to purchase common stock			-			-			330
	Stock options to purchase common stock			4,400			3,633			1,818
	Restricted stock and restricted stock units			21			93			216
	Segment Information—The Company currently operates in one business segment, which is the development and commercialization of inhaled therapies for patients with serious lung diseases. A single management team that reports to the Chief Executive Officer comprehensively manages the entire business. The Company does not operate separate lines of business with respect to its products or product candidates. Accordingly, the Company does not have separate reportable segments.
	New Accounting Pronouncements—In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606), ("ASU 2014-09"). ASU 2014-09 outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. This new revenue recognition model provides a five-step analysis in determining when and how revenue is recognized. The new model will require revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration a company expects to receive in exchange for those goods or services. ASU 2014-09 is effective for public entities for annual reporting periods beginning after December 15, 2016 and interim periods within those periods. Early adoption is not permitted. Companies may use either a full retrospective or a modified retrospective approach to adopt ASU 2014-09. The Company is currently evaluating the impact this standard will have on its operating results in future periods when revenue is recorded.

Accrued_Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2014
Accrued Expenses
Accrued Expenses	3.        Accrued Expenses
	Accrued expenses consist of the following:
		As of December 31,
		2014		2013
		(in thousands)
	Accrued clinical trial expenses	$	2,113	$	2,484
	Accrued technical operation expenses		762		1,220
	Accrued construction costs		1,500		-
	Accrued professional fees		542		24
	Accrued interest payable		258		159
	Other accrued expenses		146		18
		$	5,321	$	3,905

Identifiable_Intangible_Assets

Identifiable Intangible Assets	12 Months Ended
	Dec. 31, 2014
Identifiable Intangible Assets
Identifiable Intangible Assets	4.        Identifiable Intangible Assets
	The Company's only identifiable intangible asset was in-process research and development ("IPRD") related to ARIKAYCE for the NTM and CF indications as of December 31, 2014 and 2013. The total intangible IPRD asset was $58.2 million as of December 31, 2014 and 2013, which resulted from the initial amount recorded at the time of the Company's merger with Transave and subsequent adjustments in the value. Historically, the Company uses the income approach to derive the fair value of in-process research and development assets. This approach calculates fair value by estimating future cash flows attributable to the assets and then discounting these cash flows to a present value using a risk-adjusted discount rate. Identifiable intangible assets are measured at their respective fair values and are not amortized until commercialization. Once commercialization occurs, intangible assets will be amortized over their estimated useful lives. The Company did not identify any indicators of impairment of its in-process research and development intangible assets as of December 31, 2014.

Fixed_Assets_net

Fixed Assets, net	12 Months Ended
	Dec. 31, 2014
Fixed Assets, net
Fixed Assets, net	5.        Fixed Assets, net
	Fixed assets are stated at cost and depreciated or amortized using the straight-line method, based on useful lives as follows:
			As of December 31,
		Estimated
	Asset Description	Useful Life (years)	2014			2013
			(in thousands)
	Lab equipment	7	$	3,449		$	3,371
	Furniture and fixtures	7		1,127			65
	Computer hardware and software	3 - 5		921			718
	Office equipment	7		65			117
	Manufacturing Equipment	7		669			375
	Leasehold improvements	lease term		4,627			612
	Construction in Progress (CIP)			-			116
				10,858			5,374
	Less accumulated depreciation			(3,324	)		(3,562	)
	Fixed assets, net		$	7,534		$	1,812
	Depreciation expense was $1.1 million, $0.7 million and $0.6 million for the years ended December 31, 2014, 2013 and 2012, respectively. Depreciation expense includes depreciation for equipment under capital lease obligations.

Debt

Debt	12 Months Ended
	Dec. 31, 2014
Debt
Debt	6.        Debt
	On June 29, 2012, the Company and its domestic subsidiaries, as co-borrowers, entered into a Loan and Security Agreement with Hercules Technology Growth Capital, Inc. ("Hercules") that allowed the Company to borrow up $20.0 million in $10.0 million increments ("Loan Agreement"). The Company borrowed the first and second $10.0 million increments by signing two Secured Promissory Notes ("Note A" and "Note B" and collectively, the "Notes") on June 29, 2012 and December 27, 2012, respectively. Notes A and B bear interest at 9.25%. Note A was originally scheduled to be repaid over a 42-month period with the first twelve monthly payments representing interest only followed by thirty monthly equal payments of principal and interest. Note B was originally scheduled to be repaid over a 36-month period with the first six monthly payments representing interest only followed by thirty monthly equal payments of principal and interest. The Loan Agreement provided that in certain circumstances the Company could delay the first principal payment by five months. In July 2013, subsequent to the completion of certain ARIKAYCE-related development milestones, the Company elected to extend the interest only period under the Notes from July 31, 2013 to December 31, 2013 and delay the first monthly principal repayments for Notes A and B from August 1, 2013 to January 1, 2014.
	On November 25, 2013, the Company and Hercules entered into an amendment (the "First Amendment") of the Loan Agreement. The First Amendment initially extended the interest-only period through June 30, 2014 and called for the first monthly principal payment on July 1, 2014. The First Amendment also allowed the Company to further extend the interest-only period through December 31, 2014 and delay the first payment of principal until January 1, 2015, so long as the Company paid a $100,000 fee and obtained positive data from its phase 2 clinical trial of ARIKAYCE in patients who have lung infections caused by nontuberculous mycobacteria (NTM). In June 2014, the Company paid the $100,000 fee and exercised its option to extend the interest-only period and delay the first payment of principal to January 1, 2015. The election and second amendment did not change the maturity date for Notes A and B, which is January 1, 2016.
	On December 15, 2014, Company and Hercules entered into a third amendment (the "Third Amendment") to the Loan Agreement. In connection with the Third Amendment, the Company paid a commitment fee of $25,000, and at the closing, paid a facility fee of $125,000. Under the Third Amendment, the amount of borrowings was increased by $5.0 million to a total of $25.0 million and the interest-only period was extended through December 31, 2015. In addition, in the event the Company receives $90.0 million in cash proceeds from the completion of certain types of equity financings, subordinated debt financings, and/or up-front cash payments from corporate transactions prior to December 31, 2015, the Company will have the option to extend the maturity date of the loan to January 1, 2018. If the Company elects to exercise such option, it must pay Hercules a $250,000 fee.
	In connection with the Third Amendment, on December 15, 2014, the Company entered into a stock purchase agreement with Hercules pursuant to which the Company issued 70,771 unregistered shares of its common stock, at a price of $14.13 per share (the closing price of the Company's Common Stock as reported by the NASDAQ Stock Market on December 12, 2014), for an aggregate purchase price of approximately $1.0 million. See Note 7 for more information related to the shares purchased under the stock purchase agreement with Hercules.
	In connection with the Loan Agreement, the Company granted the lender a first position lien on all of the Company's assets, excluding intellectual property. Prepayment of the loans made pursuant to the Loan Agreement is subject to penalty and the Company is required to pay an "end of term" charge of $390,000, which is being charged to interest expense (and accreted to the debt) using the effective interest method over the life of the Loan Agreement. If the Company exercises its option to extend the maturity of the debt to January 1, 2018, the end of term charge will be due on January 1, 2016. Debt issuance fees paid to the lender were recorded as a discount on the debt and are being amortized to interest expense using the effective interest method over the life of the Loan Agreement. Debt issuance fees paid to third parties were capitalized and are being amortized to interest expense using the effective interest method over the life of the Loan Agreement.
	The Loan Agreement also contains representations and warranties by us and the lender and indemnification provisions in favor of the lender and customary covenants (including limitations on other indebtedness, liens, acquisitions, investments and dividends, but no financial covenants), and events of default (including payment defaults, breaches of covenants following any applicable cure period, a material impairment in the perfection or priority of the lender's security interest or in the collateral, and events relating to bankruptcy or insolvency). Upon the occurrence of an event of default, a default interest rate of an additional 5% may be applied to the outstanding loan balances, and the lender may terminate its lending commitment, declare all outstanding obligations immediately due and payable, and take such other actions as set forth in the Loan Agreement. In addition, pursuant to the Loan Agreement, the lender has the right to participate, in an amount of up to $1.0 million, in certain future private equity financing(s) by the Company.
	In conjunction with entering into the original Loan Agreement in 2012, the Company granted a warrant to the lender to purchase shares of the Company's common stock. Since the warrant was granted in conjunction with entering into the Loan Agreement, the relative fair value of the warrant was recorded as equity and debt discount. On April 30, 2013, the lender exercised the warrant in full. The debt discount is being amortized to interest expense over the term of the related debt using the effective interest method.
	The following table presents the components of the Company's debt balance as of December 31, 2014:
		December 31, 2014
		(in thousands)
	Debt:
	Notes payable	$	25,000
	Accretion of end of term charge		314
	Issuance fees paid to lender		(308	)
	Discount from warrant		(150	)
	Current portion of long-term debt		-
	Long-term debt	$	24,856
	Future principal repayments of the Company's long-term debt are as follows (in thousands):
	Year Ending in December 31:
	2015	$	-
	2016		25,000
		$	25,000
	The estimated fair value of the debt (categorized as a Level 2 liability for fair value measurement purposes) is determined using current market factors and the ability of the Company to obtain debt at comparable terms to those that are currently in place. As of December 31, 2014, the fair value of the Company's debt approximates the carrying amount.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2014
Stockholders' Equity
Stockholders' Equity	7.        Stockholders' Equity
	Common Stock—As of December 31, 2014, the Company had 500,000,000 shares of common stock authorized with a par value of $0.01 and 49,806,131 shares of common stock issued and outstanding. In addition, as of December 31, 2014, the Company had reserved 4,400,106 shares of common stock for issuance upon the exercise of outstanding common stock options and 20,502 for issuance upon the vesting of restricted stock units.
	On December 15, 2014, in connection with the Third Amendment to the Loan Agreement, the Company entered into a stock purchase agreement with Hercules pursuant to which the Company issued 70,771 shares of its common stock, at a price of $14.13 per share (the closing price of the Company's Common Stock as reported by the NASDAQ Stock Market on December 12, 2014), for an aggregate purchase price of approximately $1.0 million. The securities sold in this private placement have not been registered under the Securities Act of 1933, as amended (the "Act") and may not be offered or sold in the United States in the absence of an effective registration statement or exemption from the registration requirements under the Act. The issuance of the securities in this transaction were exempt from registration under Section 4(2) of the Securities Act of 1933.
	On August 18, 2014, the Company completed an underwritten public offering of 10,235,000 shares of the Company's common stock, which included the underwriter's exercise in full of its over-allotment option of 1,335,000 shares, at a price to the public of $11.25 per share. The Company's net proceeds from the sale of the shares, after deducting the underwriter's discount and offering expenses of $7.1 million, were $108.0 million.
	On July 22, 2013, the Company completed an underwritten public offering of 6,900,000 shares of the Company's common stock, which included the underwriter's exercise in full of its over-allotment option of 900,000 shares, at a price to the public of $10.40 per share. The Company's net proceeds from the sale of the shares, after deducting the underwriter's discount and offering expenses of $4.7 million, were $67.0 million.
	On September 28, 2012, the Company completed a registered direct public offering of 6,304,102 shares of the Company's common stock to certain investors at a price of $4.07 per share, resulting in proceeds of $25.7 million.
	Preferred Stock—As of December 31, 2014 and 2013, the Company had 200,000,000 shares of preferred stock authorized with a par value of $0.01 and no shares of preferred stock were issued and outstanding.
	Warrant—In conjunction with entering into the Loan Agreement in 2012 (See Note 6 — Debt), the Company granted a warrant to the lender to purchase 329,932 shares of the Company's common stock at an exercise price of $2.94 per share. The fair value of the warrant of $0.8 million was calculated using the Black-Scholes warrant-pricing methodology at the date of issuance and was recorded as equity and as a discount to the debt and was amortized to interest expense over the term of the related debt using the effective interest method. On April 30, 2013, the lender exercised the warrant in full via the "net issuance" method specified in the warrant agreement. In accordance with such provisions, the Company issued and delivered 223,431 shares of common shares to the lender on May 1, 2013. As a result of the exercise, the warrant is no longer outstanding and there are no additional shares issuable under this instrument.

StockBased_Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2014
Stock-Based Compensation
Stock-Based Compensation	8.        Stock-Based Compensation
	The Company currently has one equity compensation plan, the 2013 Incentive Plan, which was approved by shareholders at the Company's Annual Meeting of Shareholders on May 23, 2013 (the "2013 Incentive Plan"). The 2013 Incentive Plan is administered by the Compensation Committee and the Board of Directors of the Company. Under the terms of the 2013 Incentive Plan, the Company is authorized to grant a variety of incentive awards based on its common stock, including stock options (both incentive stock options and non-qualified stock options), performance options/shares and other stock awards, as well as the payment of incentive bonuses to all employees and non-employee directors. The 2013 Incentive Plan provides for the issuance of a maximum of 3,053,833 shares of common stock. Shares subject to outstanding awards under the 2000 Stock Incentive Plan that are cancelled, expired, forfeited or otherwise not issued will also be added to the number of shares available under the 2013 Incentive Plan. As of December 31, 2014, 508,062 shares of the Company's common stock were reserved for future grants (or issuances) of restricted stock, restricted stock units, stock options, and stock warrants under the 2013 Incentive Plan. The 2013 Incentive Plan will terminate on April 16, 2023 unless it is extended or terminated earlier pursuant to its terms.
	During 2013, the Company had three equity compensation plans: the 2013 Incentive Plan, the Amended and Restated 2000 Stock Incentive Plan, as amended (the "2000 Stock Incentive Plan") and the Amended and Restated 2000 Employee Stock Purchase Plan (the "Stock Purchase Plan"). Both the 2000 Stock Incentive Plan and the Stock Purchase Plan were adopted by the Company's Board of Directors in 2000. Upon the approval of the 2013 Incentive Plan, no additional awards were issued under the 2000 Stock Incentive Plan and the shares remaining for future grant under the 2000 Stock Incentive Plan were transferred to the 2013 Incentive Plan.
	During the first quarter of 2013, the Company completed a review of equity compensation awards granted under its 2000 Stock Incentive Plan and determined that it had inadvertently exceeded the annual per-person sub-limits involving certain awards previously made to certain of its current and past officers and directors (the "excess awards"). The aggregate amount of common stock represented by these excess awards, which consisted of RSUs and stock options, was approximately 1.4 million shares. These awards were deemed to be granted outside of the 2000 Stock Incentive Plan and as such the Company applied liability accounting to these awards. On May 23, 2013 (the date of the Company's 2013 Annual Meeting of Stockholders), shareholders approved the grants associated with the excess awards, which as of this date, allowed the excess awards to be deemed granted under the 2000 Stock Incentive Plan. As a result, the excess awards were re-measured at fair value on May 23, 2013 and the liability was reclassified to additional paid-in capital. The unrecognized fair value calculated for the excess awards as of May 23, 2013 will be recognized as compensation expense ratably over the remaining requisite service period for each award.
	Stock Options—The Company calculates the fair value of stock options granted using the Black-Scholes valuation model. The Company calculated the fair value of stock options granted outside of the 2000 Stock Incentive Plan using liability accounting. These awards were classified as a liability and were re-measured at fair value at the end of each reporting period using the Black-Scholes valuation model and changes in fair value were included in compensation expense in the Consolidated Statements of Comprehensive Loss (see additional disclosures related to stock options granted outside the 2000 Stock Incentive Plan at the end of this footnote).
	The following table summarizes the grant date fair value and assumptions used in determining the fair value of stock options granted under and outside the 2013 Incentive Plan and the 2000 Stock Incentive Plan, as well as grants of inducement shares, during the years ended December 31, 2014, 2013 and 2012.
			2014		2013		2012
	Volatility		83% - 86%		86% - 96%		99% - 107%
	Risk-free interest rate		1.46% - 1.83%		0.65% - 1.65%		0.57% - 0.99%
	Dividend yield		0.00%		0.00%		0.00%
	Expected option term (in years)		6.25		6.25		6.25
	Weighted-average fair value of stock options granted		$11.74		$8.16		$3.21
	For the years ended December 31, 2014, 2013 and 2012, the volatility factor was based on the Company's historical volatility since the closing of the Merger on December 1, 2010. The expected life was determined using the simplified method as described in ASC Topic 718, "Accounting for Stock Compensation", which is the midpoint between the vesting date and the end of the contractual term. The risk-free interest rate was based on the US Treasury yield in effect at the date of grant. Forfeitures are based on actual percentage of option forfeitures since the closing of the Merger on December 1, 2010, and this is the basis for future forfeiture expectations.
	From time to time, the Company grants performance-condition options to certain employees. Vesting of these options is subject to the Company achieving certain performance criteria established at the date of grant and the individuals fulfilling a service condition (continued employment). As of December 31, 2014, the Company had performance options totaling 396,667 shares outstanding. As a result of the Marketing Authorization Application ("MAA") acceptance for ARIKAYCE, which was received from the European Medicines Agency ("EMA") in February 2015, performance options totaling $1.5 million will be recorded as non-cash compensation expense in the first quarter of 2015.
	The following table summarizes stock option activity for stock options granted under the 2013 Incentive Plan and the 2000 Stock Incentive Plan, as well as grants of inducement shares, for the years ended December 31, 2014, 2013 and 2012 as follows:
			Number of			Weighted			Weighted			Aggregate
			Shares			Average			Average			Intrinsic
						Exercise			Remaining			Value
						Price			Contractual			(in '000)
									Life in Years
	Options outstanding at December 31, 2011			891,751		$	5.15
	Granted			1,116,384			4.12
	Exercised			(30,250	)		7.08
	Forfeited and expired			(160,046	)		9.54
	Options outstanding at December 31, 2012			1,817,839			4.1
	Vested and expected to vest at December 31, 2012			1,692,915			4.11
	Exercisable at December 31, 2012			438,145			4.59
	Options outstanding at December 31, 2012			1,817,839		$	4.1
	Granted			2,323,500			10.53
	Exercised			(371,743	)		4.37
	Forfeited and expired			(136,600	)		10.49
	Options outstanding at December 31, 2013			3,632,996			7.94
	Vested and expected to vest at December 31, 2013			3,402,306			7.88
	Exercisable at December 31, 2013			484,213			4.25
	Options outstanding at December 31, 2013			3,632,996		$	7.94
	Granted			1,600,452			16.1
	Exercised			(283,057	)		6.11
	Forfeited and expired			(550,285	)		11.42
	Options outstanding at December 31, 2014			4,400,106			10.59			8.47		$	24,172
	Vested and expected to vest at December 31, 2014			3,891,511			10.32			8.43		$	22,304
	Exercisable at December 31, 2014			1,235,710			6.9			7.94		$	10,597
	The total intrinsic value of stock options exercised during the years ended December 31, 2014, 2013 and 2012 was $2.5 million, $2.7 million and $0, respectively.
	As of December 31, 2014, there was $24.0 million of unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted average period of 2.4 years. Included above in unrecognized compensation expense was $3.2 million related to outstanding performance-based options. The following table summarizes the range of exercise prices and the number of stock options outstanding and exercisable as of December 31, 2014:
	Outstanding as of December 31, 2014														Exercisable as of
															December 31, 2014
	Range of						Number of			Weighted			Weighted		Number of		Weighted
	Exercise Prices						Options			Average			Average		Options		Average
										Remaining			Exercise Price				Exercise
										Contractual Term							Price
										(in years)
	$	3.03		$	3.29			180,804			6.97		$	3.05		132,114	$	3.04
	$	3.40		$	3.40			708,314			7.69		$	3.40		354,158	$	3.40
	$	3.60		$	6.90			737,098			7.93		$	6.17		358,968	$	6.15
	$	6.96		$	11.81			426,325			8.41		$	9.54		116,738	$	9.22
	$	12.44		$	12.44			506,915			8.39		$	12.44		138,557	$	12.44
	$	12.58		$	12.58			581,300			9.42		$	12.58		25,000	$	12.58
	$	12.66		$	14.24			443,300			9.03		$	13.83		73,750	$	14.06
	$	14.32		$	19.40			444,750			9.10		$	17.25		36,425	$	15.48
	$	19.88		$	20.49			356,300			9.03		$	20.46		-		-
	$	21.54		$	21.54			15,000			9.05		$	21.54		-		-
	Restricted Stock and Restricted Stock Units—The Company may grant Restricted Stock ("RS") and Restricted Stock Units ("RSUs") to employees and non-employee directors. Each RS and RSU represents a right to receive one share of the Company's common stock upon the completion of a specific period of continued service or achievement of a certain milestone. RS and RSU awards granted under the Company's 2013 Incentive Plan and 2000 Stock Incentive Plan are valued at the market price of the Company's common stock on the date of grant. The Company recognizes noncash compensation expense for the fair values of these RS and RSUs on a straight-line basis over the requisite service period of these awards.
	The following table summarizes RSU awards granted under the 2013 Incentive Plan and the 2000 Stock Incentive Plan during the years ended December 31, 2014, 2013 and 2012:
			Number of			Weighted
			RSU's			Average
			Grant Price
Outstanding at December 31, 2011			487,025		$	6.37
Granted			61,011			3.44
Released			(322,819	)		4.59
Forfeited			(9,692	)		5.69
Outstanding at December 31, 2012			215,525		$	6.26
Granted			55,317			6.77
Released			(177,316	)		6.42
Forfeited			(885	)		5
Outstanding at December 31, 2013			92,641		$	6.27
Granted			20,502			19.47
Released			(92,641	)		6.27
Forfeited			-			-
Outstanding at December 31, 2014			20,502		$	19.47
Expected to Vest			20,502		$	19.47
Awards Granted Outside of the 2000 Stock Incentive Plan—As described above, during the first quarter of 2013, the Company completed a review of equity compensation awards granted under its 2000 Stock Incentive Plan and determined that it had inadvertently exceeded the annual per-person sub-limits involving certain awards previously made to certain of its current and past officers and directors (the "excess awards"). The aggregate amount of common stock represented by these excess awards, which consisted of RSUs and stock options, was approximately 1.4 million shares. These awards were deemed to be granted outside of the 2000 Stock Incentive Plan and as such the Company applied liability accounting to these awards. On May 23, 2013 (the date of the Company's 2013 Annual Meeting of Stockholders), shareholders approved the grants associated with the excess awards, which as of this date, allowed the excess awards to be deemed granted under the 2000 Stock Incentive Plan. As a result, the excess awards were re-measured at fair value on May 23, 2013 and the liability was reclassified to additional paid-in capital. The unrecognized fair value calculated for the excess awards as of May 23, 2013 will be recognized as compensation expense ratably over the remaining requisite service period for each award.
The following table summarizes the stock-based compensation recorded in the Consolidated Statements of Comprehensive Loss related to stock options and RSUs during the years ended December 31, 2014, 2013 and 2012:
				2014			2013			2012
				(in millions)
Research and development expenses				$	4.5		$	2.4		$	0.7
General and administrative expenses					6.8			6.3			2.3
		Total		$	11.3	-1	$	8.7	-1	$	3.0
-1	Includes $2.4 and $4.1 million for the years ended December 31, 2014 and 2013, respectively, for the remeasurement of certain stock options and RSUs that occurred during May 2013.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2014
Income Taxes
Income Taxes	9.        Income Taxes
	The benefit for income taxes was $10.4 million and $1.2 million and the effective rates were approximately 12% and 2% for the years ended December 31, 2014 and 2013, respectively. The provision for income taxes was $0 and the effective rate was 0.0% during the year ended December 31, 2012. The benefit for income taxes recorded and the effective tax rates for the year ended December 31, 2014 and 2013 solely reflect the reversal of valuation allowances previously recorded against the Company's New Jersey State net operating losses ("NOL") that resulted from the Company's sale of $110.5 million and $27.0 million of its New Jersey State NOLs under the State of New Jersey's Technology Business Tax Certificate Transfer Program (the "Program") for cash of $10.4 million and $1.2 million, respectively, net of commissions. The Program allows qualified technology and biotechnology businesses in New Jersey to sell unused amounts of NOLs and defined research and development tax credits for cash.
	The Company is subject to US federal and state income taxes. The Company has never been audited and the statute of limitations for tax audit is open for the federal tax returns for the years ended 2011 and later and is generally open for certain states for the years 2010 and later. However, except in 2009, the Company has incurred net operating losses since inception. Such loss carryforwards would be subject to audit in any tax year in which those losses are utilized, notwithstanding the year of origin. The Company's policy is to recognize interest accrued related to unrecognized tax benefits and penalties in income tax expense. The Company has recorded no such expense. As of December 31, 2014 and 2013, the Company has recorded no reserves for unrecognized income tax benefits, nor has it recorded any accrued interest or penalties related to uncertain tax positions. The Company does not anticipate any material changes in the amount of unrecognized tax positions over the next twelve months.
	The reconciliation between the federal statutory tax rate of 34% and the Company's effective tax rate is as follows:
		Years Ended
		December 31,
		2014			2013			2012
	Statutory federal tax rate		34	%		34	%		34	%
	Permanent items		(3	)%		0	%		0	%
	State income taxes, net of federal benefit		(7	)%		7	%		4	%
	R&D and other tax credits		5	%		7	%		1	%
	Expired net operating loss carryforwards		0	%		0	%		(15	)%
	Change in state tax rate		0	%		2	%		0	%
	Change in valuation allowance		(17	)%		(49	)%		(22	)%
	Other		0	%		1	%		(2	)%
	Effective tax rate		12	%		2	%		0	%
	Deferred tax assets and liabilities are determined based on the difference between financial statement and tax bases using enacted tax rates in effect for the year in which the differences are expected to reverse. The components of the deferred tax assets and liabilities consist of the following:
		As of December 31,
		2014			2013
		(in thousands)
	Deferred tax assets:
	Net operating loss carryforwards	$	160,758		$	149,753
	General business credits		18,150			15,209
	Alternative minimum tax (AMT) credit		418			418
	Other		7,863			5,951
	Gross deferred tax assets	$	187,189		$	171,331
	Deferred tax liabilities:
	In-process research and development	$	(23,245	)	$	(23,245	)
	Deferred tax liabilities	$	(23,245	)	$	(23,245	)
	Net deferred tax assets	$	163,944		$	148,086
	Valuation allowance		(163,944	)		(148,086	)
	Net deferred tax assets	$	-		$	-
	The net deferred tax assets (prior to applying the valuation allowance) of $163.9 million and $148.1 million at December 31, 2014 and 2013, respectively, primarily consist of net operating loss carryforwards for income tax purposes. Due to the Company's history of operating losses, the Company recorded a full valuation allowance on its net deferred tax assets by increasing the valuation allowance by $15.8 million in 2014 as it is more likely than not that such tax benefits will not be realized.
	At December 31, 2014, the Company had federal net operating loss carryforwards for income tax purposes of approximately $461.8 million. Due to the limitation on NOLs as more fully discussed below, $283.5 million of the NOLs are available to offset future taxable income, if any. The NOL carryovers and general business tax credits expire in various years beginning in 2018. For state tax purposes, the Company has approximately $63 million of New Jersey NOLs available to offset against future taxable income or to be sold as part of the New Jersey Transfer Program. The Company also has California and Virginia NOLs that are entirely limited due to Section 382 (as discussed below), in addition to changing state apportionment allocations, as the Company is now 100% resident in New Jersey.
	During 2014, the Company completed an Internal Revenue Code Section 382 ("Section 382") analysis in order to determine the amount of losses that are currently available to offset against future taxable income, if any. It was determined that the utilization of the Company's NOL and general business tax credit carryforwards generated in tax periods up to and including December 2010 (the "December 2010 and prior NOLs") were subject to substantial limitations under Section 382 due to ownership changes that occurred at various points from its original organization through December 2010. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50 percentage points over a three-year period. Since the Company's formation, it has raised capital through the issuance of common stock on several occasions which, combined with the purchasing shareholders' subsequent disposition of those shares, resulted in multiple changes in ownership, as defined by Section 382 since the Company's formation in 1999. These ownership changes resulted in substantial limitations on the use of the Company's NOLs and general business tax credit carryforwards up to and including December 2010. The Company continues to track all of its NOLs and tax credit carryforwards but has provided a full valuation allowance to offset those amounts.

License_and_Collaboration_Agre

License and Collaboration Agreements	12 Months Ended
	Dec. 31, 2014
License and Collaboration Agreements
License and Collaboration Agreements	10.    License and Collaboration Agreements
	In-License Agreements
	PARI Pharma GmbH—In April 2008, the Company entered into a licensing agreement with PARI Pharma GmbH ("PARI") for use of the optimized eFlow Nebulizer System for delivery of ARIKAYCE in treating patients with NTM infections, CF and bronchiectasis. The Company has rights to several US and foreign issued patents and patent applications involving improvements to the optimized eFlow Nebulizer System. Under the licensing agreement, PARI is entitled to 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 ARIKAYCE and the device, first receipt of marketing approval in the US for ARIKAYCE and the device, and first receipt of marketing approval in a major EU country for ARIKAYCE and the device. In addition, PARI is entitled to receive royalty payments on commercial sales of ARIKAYCE. See below for information related to the commercialization agreement with PARI.
	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 (now Shire plc) 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 in exchange for royalty payments on commercial sales of IGF-1 (the "Premacure License Agreement"). In March 2013, the Company amended the Premacure License Agreement to provide Premacure with the option, exercisable by Premacure any time prior to April 30, 2013, to pay the Company $11.5 million (the "Buyout Amount") and assume any of the Company's royalty obligations to other parties in exchange for a fully paid license. On April 29, 2013, Premacure exercised this option and paid the Company $11.5 million in exchange for a fully paid license. The Company recorded this payment as other revenue in the three months ended June 30, 2013. The Company is not entitled to any additional future royalties from Premacure, and Premacure has assumed the Company's royalty obligations to other parties under the Premacure License Agreement.
	Collaboration Agreements
	Cystic Fibrosis Foundation Therapeutics, Inc.—In 2004 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 ARIKAYCE product. If ARIKAYCE 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 global sales milestones are met within 5 years of the drug commercialization, the Company would owe an additional payment of $3.9 million. Since there is significant development risk associated with ARIKAYCE, the Company has not accrued these obligations.
	National Institutes of Allergy and Infectious Diseases—In 2009 and 2012, the Company entered into a cooperative research and development agreement (CRADA) with National Institute of Allergy and Infectious Diseases (NIAID) to design and conduct the Company's phase 2 study of ARIKAYCE in patients with NTM. NIAID has also agreed to provide biostatistical advisory input in connection with the phase 2 NTM study. If the Company decides not to continue with the commercialization of ARIKAYCE 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.
	Therapure Biopharma Inc.—In February 2014, the Company entered into a Contract Manufacturing Agreement with Therapure Biopharma Inc. ("Therapure") for the manufacture of the Company's product ARIKAYCE. Pursuant to the agreement, the Company and Therapure are collaborating to construct a production area for the manufacture of ARIKAYCE in Therapure's existing manufacturing facility in Mississauga, Ontario, Canada. Therapure will manufacture ARIKAYCE for the Company on a non-exclusive basis. The agreement has an initial term of five years from the first date on which Therapure delivers ARIKAYCE to Insmed after Insmed obtains permits related to the manufacture of ARIKAYCE, and will renew automatically for successive periods of two years each, unless terminated by either party by providing the required two years' prior written notice to the other party. Notwithstanding the foregoing, the parties have rights and obligations under the agreement prior to the commencement of the initial term. The agreement allows for termination by either party upon the occurrence of certain events, including (i) the material breach by the other party of any provision of the agreement or the quality agreement expected to be entered into between the parties, or (ii) the default or bankruptcy of the other party. In addition, the Company may terminate the agreement for any reason upon no fewer than one hundred eighty days' advance notice. Costs incurred under this agreement will be recorded as a component of research and development expense until such time as the Company receives regulatory approvals for ARIKAYCE.
	PARI Pharma GmbH—In July 2014, the Company entered into a Commercialization Agreement with PARI for the manufacture and supply of eFlow nebulizer device as optimized for use with the Company's proprietary liposomal amikacin for inhalation. The agreement has an initial term of fifteen years from the first commercial sale of the device (the "Initial Term"). The term of the agreement may be extended by the Company for an additional five years by providing written notice to PARI at the least one year prior to the expiration of the Initial Term. Notwithstanding the foregoing, the parties have certain rights and obligations under the agreement prior to the commencement of the Initial Term. The agreement allows for termination by either party upon the occurrence of certain events, including (i) the material breach by the other party of any provision of the agreement, (ii) the default or bankruptcy of the other party, or (iii) upon termination by the Company of the License Agreement between the parties.
	SynteractHCR, Inc.—In December 2014, the Company, entered into Work Order 1, pursuant to a Master Agreement for services with SynteractHCR, Inc., ("Synteract"), dated as of August 27, 2014, as amended on December 23, 2014, pursuant to which the Company retained Synteract to perform implementation and management services in connection with certain clinical trials pursuant to a specific protocol of pharmaceutical products under development by or under the control of the Company. Synteract is providing comprehensive services for the 212 study. Prior to the execution of the Work Order, Synteract was providing such services pursuant to a Letter of Intent, dated August 25, 2014. The Work Order covers services related to the 212 study only and any additional Study will be subject to the negotiation and execution of an additional work order.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies
Commitments and Contingencies	11.    Commitments and Contingencies
	Commitments
	The Company has an operating lease for office and laboratory space located in Bridgewater, NJ that terminates in November 2019. Future minimum rental payments under this lease are $3.5 million. The Company also leases office space in Richmond, VA, where the Company's corporate headquarters were previously located, through October 2016. Future minimum rental payments under this lease total approximately $0.9 million. During 2011, the Company recorded a net present value charge of $1.2 million in general and administrative expenses associated with vacating the Richmond facility. The remaining accrual for this charge was $0.4 million as of December 31, 2014. In December 2014, the Company entered into an agreement to sublet this space for the remainder of the lease term.
	Rent expense charged to operations, net of rental income recorded, was $1.3 million, $1.0 million, and $1.0 million for the years ended December 31, 2014, 2013 and 2012, respectively. Future minimum rental payments required under the Company's operating leases are as follows (in thousands):
	Year Ending in December 31:
	2015	$	1,106
	2016		1,144
	2017		741
	2018		762
	2019		718
		$	4,471
	Legal Proceedings
	From time to time, the Company is a party to various other lawsuits, claims and other legal proceedings that arise in the ordinary course of business. While the outcomes of these matters are uncertain, management does not expect that the ultimate costs to resolve these matters will have a material adverse effect on the Company's consolidated financial position, results of operations or cash flows.

Quarterly_Financial_Data_Unaud

Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Data (Unaudited)
Quarterly Financial Data (Unaudited)	12.    Quarterly Financial Data (Unaudited)
	The following table summarizes unaudited quarterly financial data for the years ended December 31, 2014 and 2013 (in thousands, except per share data).
		2014
		First			Second			Third			Fourth			Total
		Quarter			Quarter			Quarter			Quarter
	Revenues	$	-		$	-		$	-		$	-		$	-
	Operating loss	$	(18,079	)	$	(22,816	)	$	(23,404	)	$	(23,066	)	$	(87,365	)
	Net loss	$	(14,298	)	$	(23,224	)	$	(23,990	)	$	(17,647	)	$	(79,159	)
	Basic and diluted net loss per share	$	(0.36	)	$	(0.59	)	$	(0.54	)	$	(0.36	)	$	(1.84	)
		2013
		First			Second			Third			Fourth			Total
		Quarter			Quarter			Quarter			Quarter
	Revenues	$	-		$	11,500		$	-		$	-		$	11,500
	Operating loss	$	(14,309	)	$	(8,270	)	$	(16,842	)	$	(15,594	)	$	(55,015	)
	Net loss	$	(13,678	)	$	(8,854	)	$	(17,327	)	$	(16,214	)	$	(56,073	)
	Basic and diluted net loss per share	$	(0.43	)	$	(0.28	)	$	(0.46	)	$	(0.41	)	$	(1.60	)
	Basic and diluted net loss per share amounts included in the above table were computed independently for each of the quarters presented. Accordingly, the sum of the quarterly basic and diluted net loss per share amounts may not agree to the total for the year.

Retirement_Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2014
Retirement Plan
Retirement Plan	13.    Retirement Plan
	The Company has a 401(k) defined contribution plan for the benefit for all employees and permits voluntary contributions by employees subject to IRS-imposed limitations. There were no employer contributions in 2014, 2013 and 2012.

Subsequent_Events

Subsequent Events	12 Months Ended
	Dec. 31, 2014
Subsequent Events.
Subsequent Events	14.    Subsequent Events
	In February 2015, the Company received notification that its MAA was validated after the EMA's pediatric committee approved the pediatric investigation plan for ARIKAYCE. As a result, the Company will record approximately $1.5 million of non-cash compensation expense related to certain performance-based stock options which will vest in the first quarter of 2015. The Company has evaluated all events and transactions since December 31, 2014 through the date of this report.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies
Use of Estimates	Use of Estimates—The preparation of the consolidated financial statements in conformity with accounting principles generally accepted in the United States (GAAP) requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions. The amounts of assets and liabilities reported in the Company's balance sheets and the amounts of expenses reported for each period presented are effected by estimates and assumptions, which are used for, but not limited to, the accounting for stock-based compensation, income taxes, loss contingencies, and accounting for research and development costs. Actual results could differ from those estimates.
Investment Income and Interest Expense	Investment Income and Interest Expense—Investment income consists of interest and dividend income earned on the Company's cash, cash equivalents and short-term investments, along with realized gains (losses) on the sale of investments. Interest expense consists primarily of interest costs related to the Company's debt.
Cash and Cash Equivalents	Cash and Cash Equivalents—The Company considers cash equivalents to be highly liquid investments with maturities of three months or less from the date of purchase.
Fixed Assets, Net	Fixed Assets, Net—Fixed assets are recorded at cost and are depreciated on a straight-line basis over the estimated useful lives of the assets. Estimated useful lives of three to five years are used for computer equipment. Estimated useful lives of seven years are used for laboratory equipment, office equipment and furniture and fixtures. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful life of the asset. Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its estimated future cash flows, then an impairment charge is recognized for the amount by which the carrying value of the asset exceeds the fair value of the asset.
Identifiable Intangible Assets	Identifiable Intangible Assets—Identifiable intangible assets are measured at their respective fair values and are not amortized until commercialization. Once commercialization occurs, these intangible assets will be amortized over their estimated useful lives. The fair values assigned to the Company's intangible assets are based on reasonable estimates and assumptions given available facts and circumstances. Unanticipated events or circumstances may occur that may require the Company to review the assets for impairment. Events or circumstances that may require an impairment assessment include negative clinical trial results, the non-approval of a new drug application by a regulatory agency, material delays in the Company's development program or a sustained decline in market capitalization.
	Indefinite-lived intangible assets are not subject to periodic amortization. Rather, indefinite-lived intangibles are reviewed for impairment by applying a fair value based test on an annual basis or more frequently if events or circumstances indicate impairment may have occurred. Events or circumstances that may require an interim impairment assessment are consistent with those described above. The Company performs its annual impairment test as of October 1 of each year.
	The Company uses the income approach to derive the fair value of in-process research and development assets. This approach calculates fair value by estimating future cash flows attributable to the assets and then discounting these cash flows to a present value using a risk-adjusted discount rate. A market based valuation approach was not considered given a lack of revenues and profits for the Company. This approach requires significant management judgment with respect to unobservable inputs such as future volume, revenue and expense growth rates, changes in working capital use, appropriate discount rates and other assumptions and estimates. The estimates and assumptions used are consistent with the Company's business plans.
Debt Issuance Costs	Debt Issuance Costs—Debt issuance costs are amortized using the effective interest rate method and amortized to interest expense over the term of the debt. Debt issuance costs paid to the lender are reflected as a discount to the debt, and debt issuance costs paid to other third parties are reflected as other assets in the consolidated balance sheets.
Fair Value Measurements	Fair Value Measurements—The Company categorizes its financial assets and liabilities measured and reported at fair value in the financial statements on a recurring basis based upon the level of judgments associated with the inputs used to measure their fair value. Hierarchical levels, which are directly related to the amount of subjectivity associated with the inputs used to determine the fair value of financial assets and liabilities, are as follows:
		Level 1—Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date.
		Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the assets or liability through correlation with market data at the measurement date and for the duration of the instrument's anticipated life.
		Level 3—Inputs reflect management's best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.
	Each major category of financial assets and liabilities measured at fair value on a recurring basis are categorized based upon the lowest level of significant input to the valuations. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Financial instruments in Level 1 generally include US treasuries and mutual funds listed in active markets.
	The Company's only assets and liabilities which were measured at fair value as of December 31, 2014 and December 31, 2013 were its cash and cash equivalents of $159.2 million and $113.9 million, respectively. These amounts were measured at Level 1 using quoted prices in active markets for identical assets at the measurement date. The Company's cash and cash equivalents permit daily redemption and the fair values of these investments are based upon the quoted prices in active markets provided by the holding financial institutions. Cash equivalents consist of liquid investments with a maturity of three months or less from the date of purchase and the short-term investments consist of instruments with maturities greater than three months.
	The Company recognizes transfers between levels within the fair value hierarchy, if any, at the end of each quarter. There were no transfers in or out of Level 1, Level 2 or Level 3 during 2014 and 2013.
	As of December 31, 2014 and 2013, the Company held no securities that were in an unrealized loss or gain position. The Company's unrealized loss on investments for the year ended 2012 was $0.5 million, which was included in other comprehensive loss. During 2012, the Company realized a net gain of $0.8 million from the sale of short term investments.
	The Company reviews the status of each security quarterly to determine whether an other-than-temporary impairment has occurred. In making its determination, the Company considers a number of factors, including: (1) the significance of the decline, (2) whether the securities were rated below investment grade, (3) how long the securities have been in an unrealized loss position, and (4) the Company's ability and intent to retain the investment for a sufficient period of time for it to recover.
Concentration of Credit Risk	Concentration of Credit Risk—Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents. The Company places its cash equivalents with high credit-quality financial institutions and may invest its short-term investments in US treasury securities, mutual funds and government agency bonds. The Company has established guidelines relative to credit ratings and maturities that seek to maintain safety and liquidity.
	The Company sources its raw materials from single suppliers. In addition, the production of the Company's lead product candidate, ARIKAYCE, is currently performed by a sole manufacturer. In February 2014, the Company entered into a contract manufacturing agreement with a second manufacturer to construct a production area and eventually supply ARIKAYCE at the larger scales necessary to support commercialization. The inability of the suppliers or manufacturers to fulfill supply requirements of the Company could materially impact future operating results. A change in the relationship with the suppliers or manufacturer, or an adverse change in their business, could materially impact future operating results.
Revenue Recognition	Revenue Recognition—The Company did not recognize any revenue in 2014 and 2012. In 2013, the Company's other revenue solely consists of an $11.5 million payment received from Premacure (now Shire plc) in exchange for the Company's right to receive royalties under its license agreement with Premacure. The Company recorded this as other revenue after all four revenue recognition criteria were present and the Company had no continuing performance obligations related to the payment received.
	The Company recognizes revenues when all of the following four criteria are present: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the fee is fixed or determinable; and collectability is reasonably assured.
	Where the Company has continuing performance obligations under the terms of a collaborative arrangement, non-refundable upfront license payments received upon contract signing are recorded as deferred revenue and recognized as revenue as the related activities are performed. The period over which these activities are to be performed is based upon management's estimate of the development period. Changes in management's estimate could change the period over which revenue is recognized. Research and/or development payments are recognized as revenues as the related research and/or development activities are performed and when the Company has no continuing performance obligations related to the research and development payment received.
	Where the Company has no continuing involvement under a collaborative arrangement, the Company records nonrefundable license fee revenues when the Company has the contractual right to receive the payment, in accordance with the terms of the collaboration agreement, and records milestones upon appropriate notification to the Company of achievement of the milestones by the collaborative partner.
	The Company recognizes revenue from milestone payments when earned, provided that (i) the milestone event is substantive and its achievability was not reasonably assured at the inception of the agreement and (ii) the Company does not have ongoing performance obligations related to the achievement of the milestone earned. Milestone payments are considered substantive if all of the following conditions are met: the milestone payment (a) is commensurate with either the vendor's performance to achieve the milestone or the enhancement of the value of the delivered item or items as a result of a specific outcome resulting from the vendor's performance to achieve the milestone, (b) relates solely to past performance, and (c) is reasonable relative to all of the deliverables and payment terms (including other potential milestone consideration) within the arrangement. Any amounts received under the agreement in advance of performance, if deemed substantive, are recorded as deferred revenue and recognized as revenue as the Company completes its performance obligations.
	With regard to recognizing revenue for multiple deliverable revenue arrangements, each deliverable within a multiple-deliverable revenue arrangement is accounted for as a separate unit of accounting if both of the following criteria are met: (1) the delivered item or items have value to the customer on a standalone basis and (2) for an arrangement that includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in the Company's control.
	In addition, multiple deliverable revenue arrangement consideration is allocated at the inception of an arrangement to all deliverables using the relative selling price method. The Company also applies a selling price hierarchy for determining the selling price of a deliverable, which includes (1) vendor-specific objective evidence, if available, (2) third-party evidence, if vendor-specific objective evidence is not available, and (3) estimated selling price if neither vendor-specific nor third-party evidence is available.
	Deferred revenue associated with a non-refundable payment received under a collaborative agreement that is terminated prior to its completion results in an immediate recognition of the deferred revenue.
Research and Development	Research and Development—Research and development expenses consist primarily of salaries, benefits and other related costs, including stock based compensation, for personnel serving in the Company's research and development functions, and other internal operating expenses, the cost of manufacturing a drug candidate, including the medical devices for drug delivery, for clinical study, the cost of conducting clinical studies, and the cost of conducting preclinical and research activities. The Company's expenses related to manufacturing its drug candidate and medical devices for clinical study are primarily related to activities at contract manufacturing organizations that manufacture ARIKAYCE and the medical devices for the Company's use. The Company's expenses related to clinical trials are primarily related to activities at contract research organizations that conduct and manage clinical trials on the Company's behalf. These contracts set forth the scope of work to be completed at a fixed fee or amount per patient enrolled. Payments under these contracts primarily depend on performance criteria such as the successful enrollment of patients or the completion of clinical trial milestones as well as time-based fees. Expenses are accrued based on contracted amounts applied to the level of patient enrollment and to activity according to the clinical trial protocol. Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. Such amounts are then recognized as an expense as the related goods are delivered or the services are performed, or when the goods or services are no longer expected to be provided.
Stock-Based Compensation	Stock-Based Compensation—The Company recognizes stock-based compensation expense for awards of equity instruments to employees and directors based on the grant-date fair value of those awards. The grant-date fair value of the award is recognized as compensation expense ratably over the requisite service period, which generally equals the vesting period of the award, and if applicable, is adjusted for expected forfeitures. The Company also grants performance-based stock options to employees. The grant-date fair value of the performance-based stock options is recognized as compensation expense over the implicit service period using the accelerated attribution method once it is probable that the performance condition will be achieved. Stock-based compensation expense is included in both research and development expenses and general and administrative expenses in the Consolidated Statements of Comprehensive Loss.
	Certain awards deemed to be granted outside of the Company's equity incentive plans require the Company to use liability accounting. These awards are classified as a liability and are remeasured at fair value at the end of each reporting period until such time they are deemed to be granted under the Company's equity incentive plans. Changes in fair value are included in compensation expense in the Consolidated Statements of Comprehensive Loss (see additional disclosures related to awards granted outside of the 2000 Stock Incentive Plan in Note 8, Stock-Based Compensation).
Income Taxes	Income Taxes—The Company accounts for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date.
	A valuation allowance is recorded to reduce the deferred tax assets to the amount that is expected to be realized. In evaluating the need for a valuation allowance, the Company takes into account various factors, including the expected level of future taxable income and available tax planning strategies. If actual results differ from the assumptions made in the evaluation of a valuation allowance, the Company records a change in valuation allowance through income tax expense in the period such determination is made.
	The Company uses a comprehensive model for how it measures, presents and discloses an uncertain tax position taken or expected to be taken in a tax return. The Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by taxing authorities, based solely on the technical merits of the position. The tax benefits recognized in the financial statements from such a position should be measured based on the largest benefit that has a greater than 50% likelihood to be sustained upon ultimate settlement. The Company has no uncertain tax positions as of December 31, 2014 that qualify for either recognition or disclosure in the consolidated financial statements.
	The Company's policy for interest and penalties related to income tax exposures is to recognize interest and penalties as a component of the income taxes on continuing operations in the Consolidated Statements of Comprehensive Loss.
Net Loss Per Common Share	Net Loss Per Common Share—Basic net loss per common share is computed by dividing net loss attributable to common stockholders by the weighted average number of common shares outstanding during the period. Diluted net loss per common share is computed by dividing net loss by the weighted average number of common shares and other dilutive securities outstanding during the period. Potentially dilutive securities from stock options, restricted stock units and warrants to purchase common stock would be antidilutive as the Company incurred a net loss in all periods presented. Potentially dilutive common shares resulting from the assumed exercise of outstanding stock options and warrants are determined based on the treasury stock method.
	The following table sets forth the reconciliation of the weighted average number of shares used to compute basic and diluted net loss per share for the years ended December 31, 2014, 2013 and 2012.
			Years Ended December 31,
			2014			2013			2012
			(In thousands, except per share amounts)
	Numerator:
	Net loss:		$	(79,159	)	$	(56,073	)	$	(41,374	)
	Denominator:
	Weighted average common shares used in calculation of basic net loss per share:			43,095			34,980			26,545
	Effect of dilutive securities:
	Common stock options			-			-			-
	Restricted stock and restricted stock units			-			-			-
	Common stock warrant			-			-			-
	Weighted average common shares outstanding used in calculation of diluted net loss per share			43,095			34,980			26,545
	Net loss per share:
	Basic and Diluted		$	(1.84	)	$	(1.60	)	$	(1.56	)
	The following potentially dilutive securities have been excluded from the computations of diluted weighted-average common shares outstanding as of December 31, 2014, 2013 and 2012 as their effect would have been anti-dilutive (in thousands).
			2014			2013			2012
	Warrants to purchase common stock			-			-			330
	Stock options to purchase common stock			4,400			3,633			1,818
	Restricted stock and restricted stock units			21			93			216
Segment Information	Segment Information—The Company currently operates in one business segment, which is the development and commercialization of inhaled therapies for patients with serious lung diseases. A single management team that reports to the Chief Executive Officer comprehensively manages the entire business. The Company does not operate separate lines of business with respect to its products or product candidates. Accordingly, the Company does not have separate reportable segments.
New Accounting Pronouncements	New Accounting Pronouncements—In May 2014, the FASB issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606), ("ASU 2014-09"). ASU 2014-09 outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. This new revenue recognition model provides a five-step analysis in determining when and how revenue is recognized. The new model will require revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration a company expects to receive in exchange for those goods or services. ASU 2014-09 is effective for public entities for annual reporting periods beginning after December 15, 2016 and interim periods within those periods. Early adoption is not permitted. Companies may use either a full retrospective or a modified retrospective approach to adopt ASU 2014-09. The Company is currently evaluating the impact this standard will have on its operating results in future periods when revenue is recorded.

Summary_of_Significant_Account2

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2014
Summary of Significant Accounting Policies
Reconciliation of the weighted average number of shares used to compute basic and diluted net loss per share
		Years Ended December 31,
		2014			2013			2012
		(In thousands, except per share amounts)
	Numerator:
	Net loss:	$	(79,159	)	$	(56,073	)	$	(41,374	)
	Denominator:
	Weighted average common shares used in calculation of basic net loss per share:		43,095			34,980			26,545
	Effect of dilutive securities:
	Common stock options		-			-			-
	Restricted stock and restricted stock units		-			-			-
	Common stock warrant		-			-			-
	Weighted average common shares outstanding used in calculation of diluted net loss per share		43,095			34,980			26,545
	Net loss per share:
	Basic and Diluted	$	(1.84	)	$	(1.60	)	$	(1.56	)
Potentially dilutive securities excluded from computations of diluted weighted-average shares outstanding
		2014			2013			2012
	Warrants to purchase common stock		-			-			330
	Stock options to purchase common stock		4,400			3,633			1,818
	Restricted stock and restricted stock units		21			93			216

Accrued_Expenses_Tables

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2014
Accrued Expenses
Accrued Expenses		As of December 31,
		2014		2013
		(in thousands)
	Accrued clinical trial expenses	$	2,113	$	2,484
	Accrued technical operation expenses		762		1,220
	Accrued construction costs		1,500		-
	Accrued professional fees		542		24
	Accrued interest payable		258		159
	Other accrued expenses		146		18
		$	5,321	$	3,905

Fixed_Assets_net_Tables

Fixed Assets, net (Tables)	12 Months Ended
	Dec. 31, 2014
Fixed Assets, net
Schedule of fixed assets
			As of December 31,
		Estimated
	Asset Description	Useful Life (years)	2014			2013
			(in thousands)
	Lab equipment	7	$	3,449		$	3,371
	Furniture and fixtures	7		1,127			65
	Computer hardware and software	3 - 5		921			718
	Office equipment	7		65			117
	Manufacturing Equipment	7		669			375
	Leasehold improvements	lease term		4,627			612
	Construction in Progress (CIP)			-			116
				10,858			5,374
	Less accumulated depreciation			(3,324	)		(3,562	)
	Fixed assets, net		$	7,534		$	1,812

Debt_Tables

Debt (Tables)	12 Months Ended
	Dec. 31, 2014
Debt
Components of the Company's debt balances
		December 31, 2014
		(in thousands)
	Debt:
	Notes payable	$	25,000
	Accretion of end of term charge		314
	Issuance fees paid to lender		(308	)
	Discount from warrant		(150	)
	Current portion of long-term debt		-
	Long-term debt	$	24,856
Future principal repayments of the Notes
	Year Ending in December 31:
	2015	$	-
	2016		25,000
		$	25,000

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2014
Stock-Based Compensation
Summary of Company's grant date fair value and assumptions used in determining fair value of stock options
			2014		2013		2012
	Volatility		83% - 86%		86% - 96%		99% - 107%
	Risk-free interest rate		1.46% - 1.83%		0.65% - 1.65%		0.57% - 0.99%
	Dividend yield		0.00%		0.00%		0.00%
	Expected option term (in years)		6.25		6.25		6.25
	Weighted-average fair value of stock options granted		$11.74		$8.16		$3.21
Summary of Company's stock option activity
			Number of			Weighted			Weighted			Aggregate
			Shares			Average			Average			Intrinsic
						Exercise			Remaining			Value
						Price			Contractual			(in '000)
									Life in Years
	Options outstanding at December 31, 2011			891,751		$	5.15
	Granted			1,116,384			4.12
	Exercised			(30,250	)		7.08
	Forfeited and expired			(160,046	)		9.54
	Options outstanding at December 31, 2012			1,817,839			4.1
	Vested and expected to vest at December 31, 2012			1,692,915			4.11
	Exercisable at December 31, 2012			438,145			4.59
	Options outstanding at December 31, 2012			1,817,839		$	4.1
	Granted			2,323,500			10.53
	Exercised			(371,743	)		4.37
	Forfeited and expired			(136,600	)		10.49
	Options outstanding at December 31, 2013			3,632,996			7.94
	Vested and expected to vest at December 31, 2013			3,402,306			7.88
	Exercisable at December 31, 2013			484,213			4.25
	Options outstanding at December 31, 2013			3,632,996		$	7.94
	Granted			1,600,452			16.1
	Exercised			(283,057	)		6.11
	Forfeited and expired			(550,285	)		11.42
	Options outstanding at December 31, 2014			4,400,106			10.59			8.47		$	24,172
	Vested and expected to vest at December 31, 2014			3,891,511			10.32			8.43		$	22,304
	Exercisable at December 31, 2014			1,235,710			6.9			7.94		$	10,597
Summary of range of exercise prices and the number of stock options outstanding and exercisable
	Outstanding as of December 31, 2014														Exercisable as of
															December 31, 2014
	Range of						Number of			Weighted			Weighted		Number of		Weighted
	Exercise Prices						Options			Average			Average		Options		Average
										Remaining			Exercise Price				Exercise
										Contractual Term							Price
										(in years)
	$	3.03		$	3.29			180,804			6.97		$	3.05		132,114	$	3.04
	$	3.40		$	3.40			708,314			7.69		$	3.40		354,158	$	3.40
	$	3.60		$	6.90			737,098			7.93		$	6.17		358,968	$	6.15
	$	6.96		$	11.81			426,325			8.41		$	9.54		116,738	$	9.22
	$	12.44		$	12.44			506,915			8.39		$	12.44		138,557	$	12.44
	$	12.58		$	12.58			581,300			9.42		$	12.58		25,000	$	12.58
	$	12.66		$	14.24			443,300			9.03		$	13.83		73,750	$	14.06
	$	14.32		$	19.40			444,750			9.10		$	17.25		36,425	$	15.48
	$	19.88		$	20.49			356,300			9.03		$	20.46		-		-
	$	21.54		$	21.54			15,000			9.05		$	21.54		-		-
Summary of Company's RSU activity
			Number of			Weighted
			RSU's			Average
						Grant Price
	Outstanding at December 31, 2011			487,025		$	6.37
	Granted			61,011			3.44
	Released			(322,819	)		4.59
	Forfeited			(9,692	)		5.69
	Outstanding at December 31, 2012			215,525		$	6.26
	Granted			55,317			6.77
	Released			(177,316	)		6.42
	Forfeited			(885	)		5
	Outstanding at December 31, 2013			92,641		$	6.27
	Granted			20,502			19.47
	Released			(92,641	)		6.27
	Forfeited			-			-
	Outstanding at December 31, 2014			20,502		$	19.47
	Expected to Vest			20,502		$	19.47
Summary of aggregate stock-based compensation recorded in the Consolidated Statements of Comprehensive Loss
					2014			2013			2012
					(in millions)
	Research and development expenses				$	4.5		$	2.4		$	0.7
	General and administrative expenses					6.8			6.3			2.3
			Total		$	11.3	-1	$	8.7	-1	$	3.0
	-1	Includes $2.4 and $4.1 million for the years ended December 31, 2014 and 2013, respectively, for the remeasurement of certain stock options and RSUs that occurred during May 2013.

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2014
Income Taxes
Reconciliation between The Federal Statutory Tax Rate and Effective Tax Rate
		Years Ended
		December 31,
		2014			2013			2012
	Statutory federal tax rate		34	%		34	%		34	%
	Permanent items		(3	)%		0	%		0	%
	State income taxes, net of federal benefit		(7	)%		7	%		4	%
	R&D and other tax credits		5	%		7	%		1	%
	Expired net operating loss carryforwards		0	%		0	%		(15	)%
	Change in state tax rate		0	%		2	%		0	%
	Change in valuation allowance		(17	)%		(49	)%		(22	)%
	Other		0	%		1	%		(2	)%
	Effective tax rate		12	%		2	%		0	%
Deferred Tax Assets and Liabilities
		As of December 31,
		2014			2013
		(in thousands)
	Deferred tax assets:
	Net operating loss carryforwards	$	160,758		$	149,753
	General business credits		18,150			15,209
	Alternative minimum tax (AMT) credit		418			418
	Other		7,863			5,951
	Gross deferred tax assets	$	187,189		$	171,331
	Deferred tax liabilities:
	In-process research and development	$	(23,245	)	$	(23,245	)
	Deferred tax liabilities	$	(23,245	)	$	(23,245	)
	Net deferred tax assets	$	163,944		$	148,086
	Valuation allowance		(163,944	)		(148,086	)
	Net deferred tax assets	$	-		$	-

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2014
Commitments and Contingencies
Future minimum rental payments required under operating leases
	Year Ending in December 31:
	2015	$	1,106
	2016		1,144
	2017		741
	2018		762
	2019		718
		$	4,471

Quarterly_Financial_Data_Unaud1

Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2014
Quarterly Financial Data (Unaudited)
Quarterly financial data (Unaudited)
		2014
		First			Second			Third			Fourth			Total
		Quarter			Quarter			Quarter			Quarter
	Revenues	$	-		$	-		$	-		$	-		$	-
	Operating loss	$	(18,079	)	$	(22,816	)	$	(23,404	)	$	(23,066	)	$	(87,365	)
	Net loss	$	(14,298	)	$	(23,224	)	$	(23,990	)	$	(17,647	)	$	(79,159	)
	Basic and diluted net loss per share	$	(0.36	)	$	(0.59	)	$	(0.54	)	$	(0.36	)	$	(1.84	)
		2013
		First			Second			Third			Fourth			Total
		Quarter			Quarter			Quarter			Quarter
	Revenues	$	-		$	11,500		$	-		$	-		$	11,500
	Operating loss	$	(14,309	)	$	(8,270	)	$	(16,842	)	$	(15,594	)	$	(55,015	)
	Net loss	$	(13,678	)	$	(8,854	)	$	(17,327	)	$	(16,214	)	$	(56,073	)
	Basic and diluted net loss per share	$	(0.43	)	$	(0.28	)	$	(0.46	)	$	(0.41	)	$	(1.60	)

Summary_of_Significant_Account3

Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2014
Computer equipment, laboratory equipment, office equipment and furniture and fixtures
Fixed Assets, Net
Estimated useful live of fixed assets	7 years
Computer hardware and software | Minimum
Fixed Assets, Net
Estimated useful live of fixed assets	3 years
Computer hardware and software | Maximum
Fixed Assets, Net
Estimated useful live of fixed assets	5 years

Summary_of_Significant_Account4

Summary of Significant Accounting Policies (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2014	Dec. 31, 2013
Summary of Significant Accounting Policies
Cash and cash equivalents		$159,200,000	$113,900,000
Securities that were in an unrealized loss or gain position		0	0
Unrealized loss on investments, net of taxes	-450,000
Gain on sale of short-term investments	$833,000

Summary_of_Significant_Account5

Summary of Significant Accounting Policies (Details 3) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2014
Income Taxes
Uncertain tax positions		$0
Premacure License Agreement
Collaboration Agreements
License revenues	$11.50

Summary_of_Significant_Account6

Summary of Significant Accounting Policies (Details 4) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Numerator:
Net loss									($79,159)	($56,073)	($41,374)
Denominator:
Weighted average common shares used in calculation of basic net loss per share:									43,095	34,980	26,545
Effect of dilutive securities:
Weighted average common shares outstanding used in calculation of diluted net loss per share									43,095	34,980	26,545
Net loss per share:
Basic and Diluted (in dollars per share)	($0.36)	($0.54)	($0.59)	($0.36)	($0.41)	($0.46)	($0.28)	($0.43)	($1.84)	($1.60)	($1.56)

Summary_of_Significant_Account7

Summary of Significant Accounting Policies (Details 5)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Information
Number of reportable segments	1
Warrant
Anti-dilutive securities excluded from computations of diluted weighted-average common shares outstanding
Potentially dilutive securities excluded from computations of diluted weighted-average shares outstanding (in shares)			330
Stock options
Anti-dilutive securities excluded from computations of diluted weighted-average common shares outstanding
Potentially dilutive securities excluded from computations of diluted weighted-average shares outstanding (in shares)	4,400	3,633	1,818
Restricted stock and restricted stock units
Anti-dilutive securities excluded from computations of diluted weighted-average common shares outstanding
Potentially dilutive securities excluded from computations of diluted weighted-average shares outstanding (in shares)	21	93	216

Accrued_Expenses_Details

Accrued Expenses (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Expenses
Accrued clinical trial expenses	$2,113	$2,484
Accrued technical operation expenses	762	1,220
Accrued construction costs	1,500
Accrued professional fees	542	24
Accrued interest payable	258	159
Other accrued expenses	146	18
Total accrued expenses	$5,321	$3,905

Identifiable_Intangible_Assets1

Identifiable Intangible Assets (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Identifiable Intangible Assets
In-process research and development	$58,200,000	$58,200,000
IPRD
Identifiable Intangible Assets
Total intangible asset	$58,200,000	$58,200,000

Fixed_Assets_net_Details

Fixed Assets, net (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment
Fixed assets, gross	$10,858	$5,374
Less accumulated depreciation	-3,324	-3,562
Fixed assets, net	7,534	1,812
Depreciation and amortization	1,073	680	561
Lab equipment
Property, Plant and Equipment
Fixed assets, gross	3,449	3,371
Estimated Useful Life	7 years
Furniture and fixtures
Property, Plant and Equipment
Fixed assets, gross	1,127	65
Estimated Useful Life	7 years
Computer hardware and software
Property, Plant and Equipment
Fixed assets, gross	921	718
Computer hardware and software | Minimum
Property, Plant and Equipment
Estimated Useful Life	3 years
Computer hardware and software | Maximum
Property, Plant and Equipment
Estimated Useful Life	5 years
Office equipment
Property, Plant and Equipment
Fixed assets, gross	65	117
Estimated Useful Life	7 years
Manufacturing Equipment
Property, Plant and Equipment
Fixed assets, gross	669	375
Estimated Useful Life	7 years
Leasehold improvements
Property, Plant and Equipment
Fixed assets, gross	4,627	612
Construction in Progress (CIP)
Property, Plant and Equipment
Fixed assets, gross		$116

Debt_Details

Debt (Details) (USD $)	0 Months Ended			12 Months Ended			0 Months Ended		1 Months Ended	0 Months Ended
	Aug. 18, 2014	Jul. 22, 2013	Sep. 28, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 15, 2014	Jun. 29, 2012	Jun. 30, 2014	Dec. 27, 2012
Debt
Net proceeds from issuance of common stock (in shares)	10,235,000	6,900,000	6,304,102
Shares price (in dollars per share)	$11.25	$10.40	$4.07
Proceeds from issuance of common stock	$108,000,000	$67,000,000	$25,700,000	$109,013,000	$67,017,000	$25,658,000
Debt:
Notes payable				25,000,000
Accretion of end of term charge				314,000
Issuance fees paid to lender				-308,000
Discount from warrant				-150,000
Long-term debt				24,856,000	16,338,000
Future principal repayments of the Notes
2016				25,000,000
Total				25,000,000
Hercules
Debt
Net proceeds from issuance of common stock (in shares)							70,771
Shares price (in dollars per share)							$14.13
Proceeds from issuance of common stock							1,000,000
Loan and Security Agreement
Debt
Maximum borrowing capacity of term loan							25,000,000	20,000,000
Number of Secured Promissory Notes								2
Period over which principal payment could be delayed				5 months
Fee paid to extend the interest-only period									100,000
Commitment fee							25,000
Facility fee							125,000
Increase in borrowing capacity							5,000,000
Amount of cash proceeds required to extend maturity date of loan							90,000,000
Maturity date extension fee							250,000
"End of term" charge								390,000
Additional interest rate in event of default (as a percent)				5.00%
Limit on lender's participation rights in certain future private equity financings				1,000,000
Notes
Debt
Interest rate (as a percent)				9.25%
Note A
Debt
Incremental amount of term loan								10,000,000
Period over which note is to be repaid								42 months
Payment periods representing interest only								12 months
Periods of equal payment of principal and interest								30 months
Note B
Debt
Incremental amount of term loan										$10,000,000
Period over which note is to be repaid										36 months
Payment periods representing interest only										6 months
Periods of equal payment of principal and interest										30 months

Stockholders_Equity_Details

Stockholders' Equity (Details) (USD $)	0 Months Ended			12 Months Ended			0 Months Ended
	Aug. 18, 2014	Jul. 22, 2013	Sep. 28, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	2-May-13	Dec. 15, 2014	Jun. 29, 2012
Stockholders' Equity
Common stock, authorized shares				500,000,000	500,000,000
Common stock, par value (in dollars per share)				$0.01	$0.01
Common stock, issued shares				49,806,131	39,137,169
Common stock, outstanding shares				49,806,131	39,137,169
Common stock disclosures
Net proceeds from issuance of common stock (in shares)	10,235,000	6,900,000	6,304,102
Number of share's exercise in full of over-allotment option by underwriter	1,335,000	900,000
Shares price (in dollars per share)	$11.25	$10.40	$4.07
Net proceeds from the sale of shares	$108,000,000	$67,000,000	$25,700,000	$109,013,000	$67,017,000	$25,658,000
Underwriter's discount and offering expenses	7,100,000	4,700,000
Preferred stock
Preferred stock, authorized				200,000,000	200,000,000
Preferred stock, par value				$0.01	$0.01
Preferred stock, shares issued				0
Preferred stock, shares outstanding				0
Warrant
Warrant disclosures
Warrant to purchase common stock, number of shares				0					329,932
Exercise price of warrants (in dollars per share)									2.94
Fair value of warrant							800,000
Warrant Shares issued and delivered							223,431
Warrant Shares outstanding				0
Stock options
Common stock disclosures
Common stock shares reserved for issuance				4,400,106
Restricted stock units
Common stock disclosures
Common stock shares reserved for issuance				20,502
Hercules
Common stock disclosures
Net proceeds from issuance of common stock (in shares)								70,771
Shares price (in dollars per share)								$14.13
Net proceeds from the sale of shares								$1,000,000

StockBased_Compensation_Detail

Stock-Based Compensation (Details)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2014
		item
Stock Based Compensation disclosures
Number of equity compensation plans		1
Previous equity compensation plan
Stock Based Compensation disclosures
RSUs and stock options in excess of the per person annual sub-limits	1,400,000
2013 Incentive Plan
Stock Based Compensation disclosures
Shares of common stock, maximum authorized for issuance		3,053,833
Shares available for grant		508,062

StockBased_Compensation_Detail1

Stock-Based Compensation (Details 2) (USD $)	12 Months Ended			3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2015
Stock Option disclosures
Granted (in shares)	1,600,452	2,323,500	1,116,384
Number of Shares
Options outstanding (in shares)	3,632,996	1,817,839	891,751
Granted (in shares)	1,600,452	2,323,500	1,116,384
Exercised (in shares)	-283,057	-371,743	-30,250
Forfeited or expired (in shares)	-550,285	-136,600	-160,046
Options outstanding (in shares)	4,400,106	3,632,996	1,817,839
Vested and expected to vest (in shares)	3,891,511	3,402,306	1,692,915
Exercisable (in shares)	1,235,710	484,213	438,145
Weighted Average Exercise Price
Options outstanding (in dollars per share)	$7.94	$4.10	$5.15
Granted (in dollars per share)	$16.10	$10.53	$4.12
Exercised (in dollars per share)	$6.11	$4.37	$7.08
Forfeited or expired (in dollars per share)	$11.42	$10.49	$9.54
Options outstanding (in dollars per share)	$10.59	$7.94	$4.10
Vested and expected to vest (in dollars per share)	$10.32	$7.88	$4.11
Exercisable (in dollars per share)	$6.90	$4.25	$4.59
Weighted Average Remaining Contractual Life
Options outstanding	8 years 5 months 19 days
Vested and expected to vest	8 years 5 months 5 days
Exercisable	7 years 11 months 9 days
Aggregate Intrinsic Value
Options outstanding (in dollars)	$24,172,000
Vested and expected to vest (in dollars)	22,304,000
Exercisable (in dollars)	10,597,000
Stock options
Fair value and assumptions used in determining fair value of stock options
Dividend yield (as a percent)	0.00%	0.00%	0.00%
Expected option term	6 years 3 months	6 years 3 months	6 years 3 months
Weighted-average fair value of stock options granted (in dollars per share)	$11.74	$8.16	$3.21
Stock options | Minimum
Fair value and assumptions used in determining fair value of stock options
Volatility (as a percent)	83.00%	86.00%	99.00%
Risk-free interest rate (as a percent)	1.46%	0.65%	0.57%
Stock options | Maximum
Fair value and assumptions used in determining fair value of stock options
Volatility (as a percent)	86.00%	96.00%	107.00%
Risk-free interest rate (as a percent)	1.83%	1.65%	0.99%
Performance shares
Number of Shares
Options outstanding (in shares)	396,667
Performance shares | Forecast
Aggregate Intrinsic Value
Performance options expense				$1,500,000

StockBased_Compensation_Detail2

Stock-Based Compensation (Details 3) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock options
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Total intrinsic value of stock options exercised during the period	$2.50	$2.70	$0
Unrecognized compensation expense related to unvested stock options	24
Expected weighted average period for recognizing unrecognized compensation expense	2 years 4 months 24 days
Performance shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Unrecognized compensation expense related to unvested stock options	$3.20
$3.03 to $3.29
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$3.03
Range of Exercise Prices upper range limit (in dollars per share)	$3.29
Number of Options outstanding (in shares)	180,804
Weighted Average Remaining Contractual Term	6 years 11 months 19 days
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$3.05
Number of Options exercisable (in shares)	132,114
Exercisable Options, Weighted Average Exercise Price (in dollars per share)	$3.04
$3.40 to $3.40
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$3.40
Range of Exercise Prices upper range limit (in dollars per share)	$3.40
Number of Options outstanding (in shares)	708,314
Weighted Average Remaining Contractual Term	7 years 8 months 9 days
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$3.40
Number of Options exercisable (in shares)	354,158
Exercisable Options, Weighted Average Exercise Price (in dollars per share)	$3.40
$3.60 to $6.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$3.60
Range of Exercise Prices upper range limit (in dollars per share)	$6.90
Number of Options outstanding (in shares)	737,098
Weighted Average Remaining Contractual Term	7 years 11 months 5 days
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$6.17
Number of Options exercisable (in shares)	358,968
Exercisable Options, Weighted Average Exercise Price (in dollars per share)	$6.15
$6.96 to $11.81
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$6.96
Range of Exercise Prices upper range limit (in dollars per share)	$11.81
Number of Options outstanding (in shares)	426,325
Weighted Average Remaining Contractual Term	8 years 4 months 28 days
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$9.54
Number of Options exercisable (in shares)	116,738
Exercisable Options, Weighted Average Exercise Price (in dollars per share)	$9.22
$12.44 to $12.44
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$12.44
Range of Exercise Prices upper range limit (in dollars per share)	$12.44
Number of Options outstanding (in shares)	506,915
Weighted Average Remaining Contractual Term	8 years 4 months 21 days
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$12.44
Number of Options exercisable (in shares)	138,557
Exercisable Options, Weighted Average Exercise Price (in dollars per share)	$12.44
$12.58 to $12.58
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$12.58
Range of Exercise Prices upper range limit (in dollars per share)	$12.58
Number of Options outstanding (in shares)	581,300
Weighted Average Remaining Contractual Term	9 years 5 months 1 day
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$12.58
Number of Options exercisable (in shares)	25,000
Exercisable Options, Weighted Average Exercise Price (in dollars per share)	$12.58
$12.66 to $14.24
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$12.66
Range of Exercise Prices upper range limit (in dollars per share)	$14.24
Number of Options outstanding (in shares)	443,300
Weighted Average Remaining Contractual Term	9 years 11 days
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$13.83
Number of Options exercisable (in shares)	73,750
Exercisable Options, Weighted Average Exercise Price (in dollars per share)	$14.06
$14.32 to $19.40
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$14.32
Range of Exercise Prices upper range limit (in dollars per share)	$19.40
Number of Options outstanding (in shares)	444,750
Weighted Average Remaining Contractual Term	9 years 1 month 6 days
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$17.25
Number of Options exercisable (in shares)	36,425
Exercisable Options, Weighted Average Exercise Price (in dollars per share)	$15.48
$19.88 to $20.49
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$19.88
Range of Exercise Prices upper range limit (in dollars per share)	$20.49
Number of Options outstanding (in shares)	356,300
Weighted Average Remaining Contractual Term	9 years 11 days
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$20.46
$21.54 to $21.54
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range
Range of Exercise Prices lower range limit (in dollars per share)	$21.54
Range of Exercise Prices upper range limit (in dollars per share)	$21.54
Number of Options outstanding (in shares)	15,000
Weighted Average Remaining Contractual Term	9 years 18 days
Outstanding Options, Weighted Average Exercise Price (in dollars per share)	$21.54

StockBased_Compensation_Detail3

Stock-Based Compensation (Details 4) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock options and RSUs
Weighted Average Grant Price
Allocated share-based compensation expense	$11.30	$8.70	$3
Stock-based compensation expense that resulted from the remeasurement of awards	2.4	4.1
Stock options and RSUs | Research and development expenses
Weighted Average Grant Price
Allocated share-based compensation expense	4.5	2.4	0.7
Stock options and RSUs | General and administrative expenses
Weighted Average Grant Price
Allocated share-based compensation expense	$6.80	$6.30	$2.30
Restricted stock units
Number of RSUs
Outstanding, beginning balance (in shares)	92,641	215,525	487,025
Granted (in shares)	20,502	55,317	61,011
Released (in shares)	-92,641	-177,316	-322,819
Forfeited (in shares)		-885	-9,692
Outstanding, ending balance (in shares)	20,502	92,641	215,525
Expected to Vest (in shares)	20,502
Weighted Average Grant Price
Outstanding weighted average grant price (in dollars per share)	$6.27	$6.26	$6.37
Granted (in dollars per share)	$19.47	$6.77	$3.44
Released (in dollars per share)	$6.27	$6.42	$4.59
Forfeited (in dollars per share)		$5	$5.69
Outstanding weighted average grant price (in dollars per share)	$19.47	$6.27	$6.26
Expected to Vest (in dollars per share)	$19.47
Restricted Stock and Restricted Stock Units
Stock Based Compensation disclosures
Number of common shares each award holder is entitled to receive	1

Income_Taxes_Details

Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes
Benefit from income taxes	$10,422,000	$1,221,000	$0
Effective tax rate (as a percent)	12.00%	2.00%	0.00%
NOL carryforwards
Increase in valuation allowance	15,800,000
Unrecognized tax benefits disclosures
Unrecognized tax benefits, interest and penalties accrued	0	0
Differences between the U.S. federal statutory tax rate and effective tax rate
Statutory federal tax rate (as a percent)	34.00%	34.00%	34.00%
Permanent items (as a percent)	-3.00%	0.00%	0.00%
State income taxes, net of federal benefit (as a percent)	-7.00%	7.00%	4.00%
R & D and other tax credits	5.00%	7.00%	1.00%
Expired net operating loss carryforwards (as a percent)	0.00%	0.00%	-15.00%
Change in state tax rate (as a percent)	0.00%	2.00%	0.00%
Change in valuation allowance (as a percent)	-17.00%	-49.00%	-22.00%
Other (as a percent)	0.00%	1.00%	-2.00%
Effective tax rate (as a percent)	12.00%	2.00%	0.00%
Deferred tax assets
Net operating loss carryforwards	160,758,000	149,753,000
General business credits	18,150,000	15,209,000
Alternative minimum tax (AMT) credit	418,000	418,000
Other	7,863,000	5,951,000
Gross deferred tax assets	187,189,000	171,331,000
Deferred tax liabilities
In-process research and development	-23,245,000	-23,245,000
Deferred tax liabilities	-23,245,000	-23,245,000
Net deferred tax assets	163,944,000	148,086,000
Valuation allowance	-163,944,000	-148,086,000
IRS
NOL carryforwards
Net operating loss carryforwards for income tax purposes	461,800,000
Net operating loss carryforwards available to offset future taxable income	283,500,000
Ownership change, as defined in Section 382, which could limit utilization of NOLs (as a percent)	50.00%
Period of time for measuring ownership changes under Section 382	3 years
New Jersey
NOL carryforwards
State NOLs sold under the State of New Jersey's Technology Business Tax Certificate Transfer Program	110,500,000	27,000,000
Cash proceeds from sale of NOLs, net of commissions	10,400,000	1,200,000
Net operating loss carryforwards available to offset future taxable income	$63,000,000
Percentage Company is resident of NJ	100

License_and_Collaboration_Agre1

License and Collaboration Agreements (Details) (USD $)	12 Months Ended		1 Months Ended	12 Months Ended			1 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2011	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2009	Dec. 31, 2005	Feb. 28, 2014	Jul. 31, 2014	Apr. 29, 2013
TriAct License Agreement
Collaboration Agreements
Number of shares received	0
Eleison License Agreement
Collaboration Agreements
License revenues		$1
Premacure License Agreement
Collaboration Agreements
License revenues				11.5
License purchase option price			11.5
Proceeds from sale of license									11.5
CFFT
Collaboration Agreements
Compensation earned under research funding agreements with CFFT					2.2	1.7
Royalty payable on approval of ARIKAYCE as commercialized drug	13.4
Royalty payment period	3 years
Period for meeting sales milestones for additional royalty payments	5 years
Royalty payable on meeting certain sales milestones	3.9
Therapure
Collaboration Agreements
Initial term of contract manufacturing agreement							5 years
Period of each automatic renewal of contract manufacturing agreement							2 years
Written notice period required for termination of contract manufacturing agreement							2 years
Therapure | Minimum
Collaboration Agreements
Advance notice period for termination of contract manufacturing agreement by the entity							180 days
PARI Agreement
Collaboration Agreements
Initial term of contract manufacturing agreement								15 years
Additional term of contract manufacturing agreement								5 years
PARI Agreement | Minimum
Collaboration Agreements
Written notice period required for termination of contract manufacturing agreement								1 year

Commitments_and_Contingencies_1

Commitments and Contingencies (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Commitments
Future minimum rental payments under leases	$4,471,000
Rent expense charged to operations	1,300,000	1,000,000	1,000,000
Future minimum rental payments under operating leases
2015	1,106,000
2016	1,144,000
2017	741,000
2018	762,000
2019	718,000
Total	4,471,000
Bridgewater New Jersey Facility
Commitments
Future minimum rental payments under leases	3,500,000
Future minimum rental payments under operating leases
Total	3,500,000
Richmond facility
Commitments
Future minimum rental payments under leases	900,000
Net present value charge				1,200,000
Remaining rental accrual	400,000
Future minimum rental payments under operating leases
Total	$900,000

Quarterly_Financial_Data_Unaud2

Quarterly Financial Data (Unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Financial Data (Unaudited)
Revenues							$11,500			$11,500
Operating loss	-23,066	-23,404	-22,816	-18,079	-15,594	-16,842	-8,270	-14,309	-87,365	-55,015	-42,438
Net loss	($17,647)	($23,990)	($23,224)	($14,298)	($16,214)	($17,327)	($8,854)	($13,678)	($79,159)	($56,073)	($41,374)
Basic and diluted net loss per share (in dollars per share)	($0.36)	($0.54)	($0.59)	($0.36)	($0.41)	($0.46)	($0.28)	($0.43)	($1.84)	($1.60)	($1.56)

Retirement_Plan_Details

Retirement Plan (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Retirement Plan
Employer contribution to retirement plan	$0	$0	$0

Subsequent_Events_Details

Subsequent Events (Details) (Performance shares, Subsequent events, USD $)	1 Months Ended
In Millions, unless otherwise specified	Feb. 28, 2015
Performance shares | Subsequent events
Subsequent Events
Future non-cash compensation expense related to certain performance-based stock options	$1.50