Capitalized Fees Paid to a Related Party (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Capitalized Fees paid to a Related Party
Net carrying value	$ 184,000		$ 184,000		$ 194,368	[1]
Amortization of capitalized fees paid to a related party	3,456	$ 3,455	10,368	$ 10,367
Estimated amortization expense for the remainder of 2016	3,500		3,500
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
Long-acting beta agonist (LABA) collaboration
Capitalized Fees paid to a Related Party
Weighted average remaining amortization period			13 years 4 months 24 days
GSK | Long-acting beta agonist (LABA) collaboration
Capitalized Fees paid to a Related Party
Estimated useful life			15 years
Gross carrying value	220,000		$ 220,000		220,000
Accumulated amortization	(36,000)		(36,000)		(25,632)
Net carrying value	184,000		184,000		194,368
Amortization of capitalized fees paid to a related party	3,456	$ 3,455	10,368	$ 10,367
GSK | Long-acting beta agonist (LABA) collaboration | United States
Capitalized Fees paid to a Related Party
Gross carrying value	120,000		120,000		120,000
GSK | Long-acting beta agonist (LABA) collaboration | Europe
Capitalized Fees paid to a Related Party
Gross carrying value	60,000		60,000		60,000
GSK | Long-acting beta agonist (LABA) collaboration | Japan
Capitalized Fees paid to a Related Party
Gross carrying value	$ 40,000		$ 40,000		$ 40,000

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