SUPPLEMENTARY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended
	Feb. 28, 2018	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total revenue		$ 18,730	$ 18,257	$ 15,008	$ 19,862	$ 29,499	$ 12,427	$ 26,150	$ 5,338	$ 71,857	$ 73,414	$ 60,370
Costs and expenses		95,220	94,872	87,184	92,338	100,071	77,628	68,626	79,004	369,614	325,329	299,121
Loss from operations		(76,490)	(76,615)	(72,176)	(72,476)	(70,572)	(65,201)	(42,476)	(73,666)	(297,757)	(251,915)	(238,751)
Net loss		$ (58,434)	$ (73,643)	$ (62,887)	$ (83,053)	$ (65,606)	$ (58,431)	$ (39,838)	$ (72,580)	$ (278,017)	$ (236,455)	$ (215,524)
Basic and diluted net loss per share (in dollars per share)		$ (0.92)	$ (1.16)	$ (1.00)	$ (1.40)	$ (1.17)	$ (1.05)	$ (0.72)	$ (1.32)	$ (4.46)	$ (4.25)	$ (3.99)
Percentage of profit share	33.00%									35.00%
YUPELRI Monotherapy
Total revenue		$ 13,550	$ 12,960	$ 10,589	$ 12,880	$ 10,352	$ 5,763	$ 3,184	$ 1
Percentage of Net Sales										35.00%
Viatris
Percentage of profit share										65.00%