DESCRIPTION OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Description of Operations (Details) - Long-Acting Beta2 Agonist (LABA) Collaboration - GSK $ in Billions	12 Months Ended
	Dec. 31, 2020 USD ($)
DESCRIPTION OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Percentage of economic interest in any future payments made under the agreements	15.00%
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	$ 3.0
Royalty rate for sales above first level of annual global net sales (as a percent)	5.00%
ANORO | Minimum
DESCRIPTION OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Royalty rate for combination products (as a percent)	6.50%
ANORO | Maximum
DESCRIPTION OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Royalty rate for combination products (as a percent)	10.00%
TRELEGY | Minimum
DESCRIPTION OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Royalty rate for combination products (as a percent)	6.50%
TRELEGY | Maximum
DESCRIPTION OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Royalty rate for combination products (as a percent)	10.00%