Intangible Assets and Goodwill (Details) (USD $)	3 Months Ended		9 Months Ended				3 Months Ended	9 Months Ended		3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Mar. 31, 2013 Research and Development Arrangement VX-222Asset	Mar. 31, 2013 VX-222Asset	Sep. 30, 2013 VX-222Asset	Sep. 30, 2013 Vertex	Dec. 31, 2013 Alios Bio Pharma Inc Research and Development Arrangement	Jun. 30, 2011 Alios Bio Pharma Inc Research and Development Arrangement
Indefinite-Lived Intangible Assets [Line Items]
Intangible asset impairment charge	$ 0	$ 0	$ 0	$ 412,900,000			$ 412,900,000	$ 412,900,000	$ 285,300,000	$ 250,600,000
Intangible assets						0				0	250,600,000
Deferred federal income tax expense (benefit)				127,600,000
Net increase to net loss per share (usd per share)									$ 1.28
Increase in deferred income taxes										102,100,000
Goodwill	30,992,000	31,000,000	30,992,000	31,000,000	30,992,000
Goodwill, period increase (decrease)	$ 0	$ 0	$ 0	$ 0