Capitalized Fees paid to a Related Party (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Capitalized Fees paid to a Related Party
Net Carrying Value	$ 204,735,000		$ 208,191,000	[1]
Amortization of capitalized fees paid to a related party	3,456,000	1,780,000
Estimated amortization expense for the remainder of 2015	10,400,000
Estimated amortization expense for the year 2016	13,800,000
Estimated amortization expense for the year 2017	13,800,000
Estimated amortization expense for the year 2018	13,800,000
Estimated amortization expense for the year 2019	13,800,000
Estimated amortization expense for the year 2020	13,800,000
Estimated amortization expense thereafter	125,300,000
GSK
Capitalized Fees paid to a Related Party
Amortization of capitalized fees paid to a related party	3,456,000	1,780,000
GSK | LABA Collaboration
Capitalized Fees paid to a Related Party
Weighted Average Remaining Amortization Period	14 years 9 months 18 days
Gross Carrying Value	220,000,000		220,000,000
Accumulated Amortization	(15,265,000)		(11,809,000)
Net Carrying Value	204,735,000		208,191,000
Amortization of capitalized fees paid to a related party	$ 3,500,000	$ 1,800,000

[1] Condensed consolidated balance sheet at December 31, 2014 has been derived from audited consolidated financial statements.