Capitalized Fees Paid to a Related Party (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Capitalized Fees paid to a Related Party
Net Carrying Value	$ 187,456		$ 187,456		$ 194,368	[1]
Amortization of capitalized fees paid to a related party	3,456	$ 3,456	6,912	$ 6,912
Estimated amortization expense for the remainder of 2016	6,900		6,900
Estimated amortization expense for the year 2017	13,800		13,800
Estimated amortization expense for the year 2018	13,800		13,800
Estimated amortization expense for the year 2019	13,800		13,800
Estimated amortization expense for the year 2020	13,800		13,800
Estimated amortization expense for the year 2021	13,800		13,800
Estimated amortization expense thereafter	111,400		111,400
GSK
Capitalized Fees paid to a Related Party
Amortization of capitalized fees paid to a related party	3,456	3,456	$ 6,912	6,912
GSK | Long-acting beta agonist (LABA) collaboration
Capitalized Fees paid to a Related Party
Weighted Average Remaining Amortization Period			13 years 7 months 6 days
Gross Carrying Value	220,000		$ 220,000		220,000
Accumulated Amortization	(32,544)		(32,544)		(25,632)
Net Carrying Value	187,456		187,456		$ 194,368
Amortization of capitalized fees paid to a related party	$ 3,500	$ 6,900	$ 3,500	$ 6,900

[1] Condensed consolidated balance sheet as of December 31, 2015 has been derived from audited consolidated financial statements.