Capitalized Fees paid to a Related Party (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Capitalized Fees paid to a Related Party
Net Carrying Value	$ 201,279		$ 201,279		$ 208,191	[1]
Amortization of capitalized fees paid to a related party	3,456	$ 2,598	6,912	$ 4,378
Estimated amortization expense for the remainder of 2015	6,900		6,900
Estimated amortization expense for the year 2016	13,800		13,800
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 thereafter	139,200		139,200
GSK
Capitalized Fees paid to a Related Party
Amortization of capitalized fees paid to a related party	3,456	2,598	$ 6,912	4,378
GSK | Long-acting beta agonist (LABA) collaboration
Capitalized Fees paid to a Related Party
Weighted Average Remaining Amortization Period			14 years 7 months 6 days
Gross Carrying Value	220,000		$ 220,000		220,000
Accumulated Amortization	(18,721)		(18,721)		(11,809)
Net Carrying Value	201,279		201,279		$ 208,191
Amortization of capitalized fees paid to a related party	$ 3,500	$ 2,600	$ 6,900	$ 4,400

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