Description of Operations and Summary of Significant Accounting Policies - Description of Operations and Variable Interest Entity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Description of Operations and Summary of Significant Accounting Policies
Net revenue	$ 55,183	$ 52,380
GSK
Description of Operations and Summary of Significant Accounting Policies
Net revenue	$ 55,183	52,380
Long-Acting Beta2 Agonist (LABA) Collaboration | GSK
Description of Operations and Summary of Significant Accounting Policies
Percentage of economic interest in any future payments made under the agreements	15.00%
Long-Acting Beta2 Agonist (LABA) Collaboration | GSK | RELVAR/BREO
Description of Operations and Summary of Significant Accounting Policies
Royalty rate for first level of annual global net sales (as a percent)	15.00%
Annual global sales level used to determine royalty rate	$ 3,000,000
Royalty rate for sales above first level of annual global net sales (as a percent)	5.00%
Long-Acting Beta2 Agonist (LABA) Collaboration | GSK | ANORO | Minimum
Description of Operations and Summary of Significant Accounting Policies
Royalty rate for combination products (as a percent)	6.50%
Long-Acting Beta2 Agonist (LABA) Collaboration | GSK | ANORO | Maximum
Description of Operations and Summary of Significant Accounting Policies
Royalty rate for combination products (as a percent)	10.00%
TRC | TRELEGY
Description of Operations and Summary of Significant Accounting Policies
Net revenue	$ 7,300	$ 1,000
TRC | Collaborative arrangement
Description of Operations and Summary of Significant Accounting Policies
Related-party receivables	$ 7,300		$ 6,400