Collaborative Arrangements Narrative (Details)			1 Months Ended		3 Months Ended					9 Months Ended		12 Months Ended
	Oct. 26, 2015 USD ($) target	Jun. 04, 2015 USD ($)	Oct. 31, 2014 USD ($)	Apr. 30, 2011 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Mar. 31, 2013 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2015 USD ($) payment	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Collaborative Arrangement Agreements [Line Items]
Collaborative revenues					$ 1,546,000		$ 33,502,000			$ 2,999,000	$ 40,846,000
Development milestones discount rate low end of range (percentage)		4.10%
Development milestones discount rate high end of range (percentage)		5.90%
Commercial milestones and royalties discount rate (percentage)		6.60%
Intangible assets					284,340,000	$ 29,000,000				284,340,000		$ 29,000,000
BioAxone Biosciences Inc
Schedule of Collaborative Arrangement Agreements [Line Items]
Up-front payment						$ 10,000,000
License fees and milestone payments (up to)			$ 90,000,000.0
Purchase option, term of extension of expiration date (in years)			1 year
Increase (decrease) in fair value of contingent milestone and royalty payments					(600,000)					(100,000)
Contingent consideration, liability					27,000,000					27,000,000
Parion Sciences, Inc
Schedule of Collaborative Arrangement Agreements [Line Items]
Up-front payment		$ 80,000,000
Prior to marketing approval, time period of notice required to terminate (in days)		90 days
Subsequent to marketing approval, time period of notice required to terminate (in days)		180 days
Change of control prior to clinical trial, time period of notice required to terminate (in days)		30 days
Term of agreement following first commercial sale (in years)		10 years
Business combination, consideration transferred		$ 255,340,000
Intangible assets		255,340,000
Increase (decrease) in fair value of contingent milestone and royalty payments					4,500,000					2,900,000
Contingent consideration, liability					178,200,000					178,200,000
Cystic Fibrosis Foundation Therapeutics Incorporated
Schedule of Collaborative Arrangement Agreements [Line Items]
Collaborative funding				$ 75,000,000
Number of years over which funding will be made (in years)				5 years
Collaborative revenues					0		2,000,000			$ 0	6,500,000
Milestone payment made								$ 9,300,000	$ 9,300,000
Number of commercial milestone payments for achievement of certain sales levels for corrector compound such as VX-809 or VX-661 (in payments) | payment										2
Janssen
Schedule of Collaborative Arrangement Agreements [Line Items]
Collaborative revenues					441,000		1,390,000			$ 1,620,000	4,262,000
Up-front payment												$ 35,000,000
Reimbursement revenue					$ 4,000,000		$ 4,300,000			$ 18,700,000	$ 4,300,000
Time period of notice required to terminate (in months)										6 months
Additional Enac Inhibitors | Parion Sciences, Inc
Schedule of Collaborative Arrangement Agreements [Line Items]
Collaborative arrangement development and regulatory potential milestone payments maximum		230,000,000
Enac Inhibitors in Non Cf | Parion Sciences, Inc
Schedule of Collaborative Arrangement Agreements [Line Items]
Collaborative arrangement development and regulatory potential milestone payments maximum		370,000,000
ENaC Inhibitors in CF | Parion Sciences, Inc
Schedule of Collaborative Arrangement Agreements [Line Items]
Collaborative arrangement development and regulatory potential milestone payments maximum		490,000,000
Collaborative arrangement regulatory potential milestone payments maximum, global filling and approval		$ 360,000,000
Subsequent Event | CRISPR Therapeutics
Schedule of Collaborative Arrangement Agreements [Line Items]
Up-front payment	$ 75,000,000.0
Investment in collaborative partner, pursuant to convertible loan agreement	$ 30,000,000.0
Right to license, number of targets (up to) | target	6
Collaborative arrangement development and regulatory potential milestone payments maximum	$ 420,000,000
Prior to marketing approval, time period of notice required to terminate (in days)	90 days
Subsequent to marketing approval, time period of notice required to terminate (in days)	270 days